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Thirteen drinks, one trial

The most hydrating drinks, measured

4 of 13 drinks held more fluid than water — for about 2-4 hours

In the trial that created the beverage hydration index, 72 men each drank a litre of still water and a litre of three of the other twelve drinks, on separate mornings. Only 4 drinks beat still water two hours later: skimmed milk at 1.58, an oral rehydration solution at 1.54, full-fat milk at 1.50 and orange juice at 1.39, against water's 1.00. The other 8 — coffee, tea, cola, diet cola, a sports drink, sparkling water, iced tea and lager — were statistically indistinguishable from water. What separates them is not the water. It is the sugar, caffeine, calories and alcohol that come with it.1

Drinks measured
131
Still water plus 12 others, about 17 drinkers each
Beat water
41
Top of the table: skimmed milk 1.58 (SD 0.60)
Matched water
81
Including coffee at 0.91 and lager at 0.99
The window
2-4 h1
Urine collected for 4 h after a litre; repeatability about 18%

Last reviewed 27 sourcesWritten from the studies, not from other websites

The measurement

Thirteen drinks, measured against still water

The beverage hydration index is one number: urine after a litre of still water, divided by urine after a litre of the test drink, two hours after drinking ended. Above 1.00 means more of it stayed in you. Everything on this chart comes from one morning per drink in 72 healthy men, so read the gaps generously — the index repeats to about 18%.

Two-hour beverage hydration index, 13 drinks against still water

Horizontal bar chart of the two-hour beverage hydration index for 13 drinks, with still water fixed at 1.00 as the reference. Skimmed milk 1.58, Oral rehydration solution 1.54, Full-fat milk 1.50, Orange juice 1.39, Cola 1.23, Diet cola 1.08, Cold black tea 1.07, Hot black tea 1.03, Sports drink 1.02, Still water 1.00, Lager 0.99, Sparkling water 0.98, Coffee (hot, black) 0.91. 4 drinks — oral rehydration solution, orange juice, full-fat milk, skimmed milk — scored significantly above still water; the other 8 were not distinguishable from it. Correcting each drink for its own water content leaves 3 above water, because orange juice falls to 1.24.

This pageAbove waterNo differenceWater = 1.00
  • Skimmed milk1.58
  • Oral rehydration solution1.54
  • Full-fat milk1.50
  • Orange juice1.39
  • Cola1.23
  • Diet cola1.08
  • Cold black tea1.07
  • Hot black tea1.03
  • Sports drink1.02
  • Still waterreference1.00
  • Lager0.99
  • Sparkling water0.98
  • Coffee (hot, black)0.91

Significance as marked on the paper’s Figure 2: ** P<0.01, * P<0.05 vs waterWhiskers are 1 SD

BHI = urine after still water ÷ urine after the test drink, 2 h after drinking ended. 72 healthy, recreationally active men aged 18-35, rested, fasted overnight and euhydrated. 1 L of each drink over 30 min in four equal portions; urine collected hourly for 4 h after drinking ended. Each man drank still water plus 3 of the 12 other drinks on separate mornings. Cold drinks 4-6 C, hot tea and coffee 60 C. Repeatability: coefficient of variation 18% (about 180 ml).1Funding: Funded by a grant from the European Hydration Institute (EHI). Prof Maughan chairs the EHI Scientific Advisory Board (not the Institute itself); Dr Watson has also received EHI funding.
Show the data table
Two-hour beverage hydration index for every drink tested, with standard deviations and how each was reported
DrinkIndex2 hCorrectedwater contentSDvs watern
Skimmed milkTesco, 0.1% fat1.581.440.60Above water17
Oral rehydration solutionDioralyte, made up with Highland Spring water1.541.500.74Above water17
Full-fat milkTesco, 3.6% fat1.501.320.58Above water17
Orange juiceTesco Everyday Value1.391.240.64≈Above water16
ColaCoca-Cola1.231.090.54≈No detected difference17
Diet colaDiet Coke1.081.080.24≈No detected difference16
Cold black teaPG tips1.071.070.59≈No detected difference17
Hot black teaPG tips1.031.030.24≈No detected difference15
Sports drinkPowerade1.020.980.24≈No detected difference17
Still waterHighland Spring1.001.00—Reference drink72
LagerCarling0.990.940.31≈No detected difference17
Sparkling waterHighland Spring0.980.980.20≈No detected difference17
Coffee (hot, black)Nescafe Original instant0.910.900.31≈No detected difference17

≈ marks a standard deviation read from the paper’s figures rather than its text. “Corrected” adjusts each drink for its own water content, which is the fairer comparison and the one that moves orange juice below significance.

What this number is not

  • — About 17 drinkers per test drink against a pooled water arm, so small differences such as coffee vs water cannot be detected.
  • — Rested, already-hydrated young men drinking 1 L in 30 min; the result describes a 2-4 h window, not all-day hydration.
  • — Caffeine at 96-212 mg in these drinks had no effect on net fluid balance. The authors cite a threshold of about 250-300 mg for a measurable diuretic effect (Maughan & Griffin 2003).
  • — The lager's alcohol content was not reported, and no numeric 4-h BHI was reported for any drink.
  • — Nine of the twelve BHI standard deviations, and eight of the twelve means, are only in the figures; they were read from the figure's vector data and match the text values to about 0.01.
  • — The abstract says the BHI was corrected for water content, but the 1.58, 1.54 and 1.50 values are the uncorrected BHI.

The table

Every drink, and what comes with it

The same thirteen drinks, plus the ten the chart never tested, with what a 250 mL glass of each actually carries. Sort by any column, filter to the drinks you care about, and follow a row through to the page that covers it. Coffee, tea and sparkling water link to our blog posts rather than to pages here.

Filter

Showing 23 of 23 drinks · everything per 250 mL (8.5 fl oz)

Every drink with its two-hour beverage hydration index where one was measured, its water content, and its calories, sugars, sodium, potassium and caffeine per 250 mL
vs water 1.00by weightper glassper glassper glassper glassper glassLogs in Water Goose as
Skim milkMilk · FDC 2705388Does milk hydrate you?1.58Above water1.44 corrected90.8%88kcal13g106mg431mg0mgMilk
Oral rehydration solutionSports and rehydration · FDC 2710775Does Gatorade hydrate you?1.54Above water1.50 corrected96.4%26kcal6.4g265mg202mg0mgSports drinkNo exact preset; sports drink is the closest.
Whole milkMilk · FDC 2705385Does milk hydrate you?1.50Above water1.32 corrected88.1%157kcal12.4g98mg387mg0mgMilk
Orange juice, 100%Juice and smoothies · FDC 2709188Does orange juice hydrate you?1.39Above water1.24 corrected88.4%123kcal21.4g5mg476mg0mgJuice
ColaSoda and energy drinks · FDC 2710541Does soda hydrate you?1.23No detected difference1.09 corrected89.4%110kcal26g8mg13mg24mgSoda
Diet colaSoda and energy drinks · FDC 2710542Does soda hydrate you?1.08No detected difference99.5%5kcal0g20mg20mg30mgSoda
Black tea, iced and unsweetenedCoffee and tea · FDC 2710517Does tea count as water intake?1.07No detected difference99.7%3kcal0g8mg94mg51mgTea
Black tea, hotCoffee and tea · FDC 2710488Does tea count as water intake?1.03No detected difference99.7%3kcal0g8mg94mg51mgTea
Sports drinkSports and rehydration · FDC 2710771Does Gatorade hydrate you?1.02No detected difference0.98 corrected93.4%68kcal13.7g102mg39mg0mgSports drink
WaterWater · FDC 2710707The reference every other drink here is measured against.1.00The reference drink99.9%0kcal0g10mg0mg0mgWater
BeerAlcohol · FDC 2710616Measured once, at rest, as a litre of lager. A measurement, not a recommendation.0.99No detected difference0.94 corrected92%109kcal0g10mg68mg0mgNot a drink typeWater Goose has no alcohol preset.
Sparkling waterWater · FDC 2710539Does sparkling water hydrate you?0.98No detected difference99.9%0kcal0g53mg5mg0mgSparkling water
Coffee, brewed and blackCoffee and tea · FDC 2710375Does coffee count towards water intake?0.91No detected difference0.90 corrected99.4%3kcal0g5mg124mg101mgCoffee
Broth-based soupOther · FDC 2707132No hydration index exists for soup. The sodium is the number worth looking at.Not measured97.7%15kcal0.6g943mg91mg0mgSoup
Almond milk, unsweetenedPlant milks · FDC 2705409Does milk hydrate you?Not measured97.4%39kcal0g155mg80mg0mgMilk
Coconut water, unsweetenedOther · FDC 2707572Never put through this protocol, so it has no index at all.Not measured95%46kcal9.9g66mg418mg0mgCoconut water
Soy milk, unsweetenedPlant milks · FDC 2705405Does milk hydrate you?Not measured92.4%98kcal1.4g88mg407mg0mgMilk
Oat milkPlant milks · FDC 2705412Does milk hydrate you?Not measured91.3%116kcal5.3g111mg46mg0mgMilk
Energy drinkSoda and energy drinks · FDC 2710756Not measured89.2%113kcal26.8g102mg8mg76mgEnergy drink
LemonadeJuice and smoothies · FDC 2710570Does orange juice hydrate you?Not measured87.9%121kcal30.6g16mg26mg0mgLemonade
Chocolate milk, low fatMilk · FDC 2705470Does milk hydrate you?Not measured84.5%168kcal26g170mg451mg3mgMilk
Fruit smoothie with dairyJuice and smoothies · FDC 2705514No hydration index exists for smoothies either.Not measured84%151kcal20.3g64mg397mg0mgSmoothie
Electrolyte drink mixSports and rehydrationUSDA has no entry for powders and tablets mixed into water, so this row carries no composition. The sports drinks page uses official label data instead.Does Gatorade hydrate you?Not measured——————WaterNo exact preset; log the water you mixed it into.

** P<0.01 vs water* P<0.05 vs water“Corrected” adjusts for the drink’s own water content

Index values are the 2-hour beverage hydration index from a single trial; "no detected difference" means the drink was not statistically separable from still water, not that it performed identically. Composition is USDA FoodData Central's generic entry for each drink, converted from per 100 grams through the item's density, so brands will differ.1,2

The rest of the evidence

What everyone else measured

The index above is one protocol in one lab. These are the other trials that measured drinks against water, including the ones with a different protocol, a different population or a funder with an interest in the answer. Post-exercise retention percentages and resting index values are different measurements — the flag on each row says which you are reading.

Other trials that measured drinks against water, with population, protocol comparability, findings and funding
StudyWho drank, and howWhat it found
Sollanek 20183At restHydration index40 euhydrated, fasted adults (17 men, 23 women)Standard 1 L BHI protocol per the abstract; repeated-measures comparison of water, an amino-acid ORS, a glucose ORS and a sports drink.Both oral rehydration solutions, but not the sports drink, gave a BHI above water. Body mass and sex did not influence the BHI.Abstract only; composition and time window are not verified beyond it.
Maughan 20194At restHydration index3 separate cohorts of 12 young active menDouble-blind crossover; 1 L of drink; 4-h urine collection; BHI and net fluid balance.Retention rose with sucrose (10-20%) and sodium (27-52 mmol/L); caffeine up to 400 mg/L had no effect.Abstract only; no numeric BHI values.
Clarke 20195At restHydration index12 young (23 ± 3 y; 7 men, 5 women) and 12 older adults (67 ± 6 y; 5 men, 7 women)Randomised crossover; 1 L of distilled water or test drink over 30 min; urine at 0, 60, 120, 180 and 240 min. Label composition, measured osmolality.Every test drink had a BHI significantly above 1.0 at both 2 and 4 h in young and older adults. Older adults retained more fluid overall, and the authors suggest a 4-h BHI for older people.Mean ± SEM, not SD; do not compare spreads with SD-based studies.Funding: Partially funded by an unrestricted gift from Entrinsic Health Solutions.
Berry 20206At restHydration index12 young adults (6 men, 6 women; about 23 y)Randomised crossover; 1 L at 16-20 C over 30 min; BHI at 120 and 240 min.The milk permeate drink retained more fluid than water and the sports drink; the sports drink's BHI did not differ from water.n=12; mean substitution for 2 missing trials.Funding: Funded by Dairy Management Inc.
Pence 20207At restHydration index18 active adults (8 men, 10 women)Crossover; 1 L over 30 min; 4-h urine; BHI.Fluid balance was better than water for both doses at 2, 3 and 4 h (p≤0.04). A double dose did not improve BHI further than a single dose.BHI values are in figures only.Funding: Provided in part by Nuun & Company, Inc., and the University of Memphis.
Millard-Stafford 20218At restHydration index19 participants (15 men, 4 women)Randomised crossover; 1 L at 10-12 C over 30 min; 240 min. Composition measured after the study; Na and K headers read 'mmol' with no volume.Adding carbohydrate to about 21 mmol/L electrolytes raised BHI above water from 120 min; electrolytes alone did not reach significance; no differences among the three test drinks.Mostly men.Funding: Funded by Coca-Cola.
Bechke 20229At restHydration index22 adults (50% women)Crossover; 1 L over 30 min; 240 min; control was distilled water (Deer Park).The isotonic drink did not differ from water at 2 h but retained more at 3 and 4 h.Funded by QCK, LLC, the maker of HOIST.Funding: Funded by QCK, LLC (grant 20-0081), the maker of HOIST.
Yun 202210At restHydration indexMale athletes (36 recruited; 31 observations analysed)Crossover; 1 L over 30 min; hourly urine for 4 h; BHI.All three drinks gave a higher BHI than water from 2 h onwards (BHI values shown only in figures).Male athletes only.Funding: Grants from Lingtea Co., Ltd., which makes the oral rehydration solution and one of the sports drinks tested.
Millard-Stafford 202511At restHydration indexDifferent protocol28 adults (14 men, 14 women); caffeine 3.7 ± 0.4 mg/kg in men and 4.8 ± 0.8 mg/kg in womenRandomised crossover; 250 mL water, 500 mL test drink, then 250 mL water, in four portions over 30 min; 240 min. Composition measured per 500 mL.The two low-sodium drinks with 280 mg caffeine retained less fluid than water at 4 h; the lower-caffeine drink with electrolytes and carbohydrate matched water. Habitual caffeine use made no difference (0.92 ± 0.1 vs 0.93 ± 0.1, p=0.827). Women had a higher BHI than men with the caffeinated drinks (reported as +0.077, p=0.043; the abstract gives p=0.03).Not the standard protocol: only 500 mL of test drink, so values are not comparable with 1-L BHI studies.Funding: Funded by Liquid-IV, a Unilever company (grant GR00027334), maker of the Liquid I.V. Energy Multiplier that matched water in the trial. A Liquid IV principal scientist helped conceptualise and review the manuscript. The first author has also had funding from Coca-Cola, Kraft and Liquid IV.
Boyd-Shiwarski 202512At restHydration indexDifferent protocol30 adults (14 men, 16 women; 18-45 y)Non-randomised, fixed order (Buoy, then water, then Nuun). Water and Buoy: 1 L sipped at a metered rate over 4 h. Nuun: 1 L over 30 min. 6-h urine collection. Mean ± SD in the text; figure error bars are 95% CI.Electrolyte drops sipped over 4 h retained more fluid than water sipped the same way; the comparison with the Nuun bolus is confounded by the different drinking patterns.Non-randomised, non-standard drinking pattern and a 6-h window.Funding: Buoy paid for part of two authors' time.
Rodriguez-Sanchez 202313At restUrine outputDifferent protocol12 young (24.5 y) and 11 older (63.8 y) men1 L over 60 min (250 mL every 15 min); urine for 3 h; no BHI calculated. Macronutrients from labels; electrolytes by flame photometry, with 'mmol' headers that give no volume.Milk improved fluid retention in young men but not in older men, who already retained more water.No BHI reported; ratios of group-mean urine are not individual-level BHI, so none are given.
Takamata 202614Mildly dehydratedFluid retainedDifferent protocol15 adults (8 women, 7 men)Drinking freely for 180 min after about 1% body-mass loss; urine in g per kg body mass.Adding sodium increased retention; carbonation did not improve it. Stomach discomfort was higher with both carbonated drinks than with still electrolyte water (p=0.019 and p=0.004).Free drinking, so volumes differ between drinks.Funding: Funded by ITO EN, Ltd.; seven of the thirteen authors are ITO EN employees.
Juett 202615After exerciseFluid retainedDifferent protocol17 adultsAfter exercise, drank 150% of about 2% body mass lost, matched for water volume; 5 h.Urine (P=0.156) and retention (P=0.059) did not differ significantly between drinks. Blood glucose rose less with the juice than with the sports drink.Post-exercise retention, not BHI; do not plot alongside BHI values.Funding: Innovate UK Knowledge Transfer Partnership with Innate-Essence, maker of the juice tested. The senior author has PepsiCo research funding.
Shirreffs 200716After exerciseFluid retainedDifferent protocol11 adults (5 men, 6 women)Dehydrated by 1.8% of body mass with exercise, then drank 150% of the loss (1.79 ± 0.42 L) over 1 h; 4-h recovery.After exercise, milk kept people in net positive fluid balance, whereas water and the sports drink did not.Post-exercise, 150% volume: not comparable with BHI values.

Only the first caveat of each study is shown here; the rest, and the arm-by-arm compositions, are on the page for the drink each one tested.

Your day

Your drinks today

Add what you have drunk today and see the volume, the water it actually delivers, and where it lands against a daily goal. Nothing leaves your browser: the list and the goal are stored on this device, and the goal is shared with the intake calculator.

What you have drunk

  • Water
    mL
  • Coffee, brewed and black
    mL
  • Orange juice, 100%
    mL
mL

68 fl oz. Not sure? The intake calculator works it out from your weight.

Beer is in the table above but not in this planner: the app has no alcohol preset, and this page does not treat alcohol as a way to hydrate. Electrolyte mixes are missing for a duller reason — USDA has no entry for powders and tablets.

3 drinks · 1,000 mL in the glass

990mL of water

33.5 fl oz of actual water, from 33.8 fl oz of drink

Share of your goal50%

Water Goose counts every drink at its full volume, with no hydration multiplier, which is the volume figure above rather than the water figure. Counted as the water each drink carries instead, it is 49.5% of the goal. EFSA and NASEM both count the water a drink carries toward your total intake — the water in it, rather than the volume of the glass.18,19

Caffeine against 400 mg101 mg

EFSA judged habitual intakes up to 400 mg a day, and single doses up to 200 mg, to raise no safety concern for healthy adults — lower in pregnancy. These are safety limits, not hydration thresholds. The full opinion was unreachable, so re-check wording before quoting verbatim.17

Calories
126kcal
Sugars
21.4g
Caffeine
101mg
Sodium
31mg
Potassium
601mg
Volume
1,000mL

Composition from USDA FoodData Central, converted through each drink’s density.2 Work out your daily goal · Track caffeine through the day

The honest part

What the index does and does not mean

This page exists because the index is genuinely useful and routinely oversold. Six things worth holding on to before you use it to change what you drink.

  • It measures two to four hours, not a day

    The index is anchored two hours after a litre of drink went down in 30 minutes, with urine collected for four. The authors say plainly that it describes short-term retention, and no study has followed these drinks against water across 24 hours. A drink that holds fluid for three hours has not been shown to leave you better hydrated at bedtime.1

  • About 17 people drank each drink

    Seventy-two men took part, but each one drank still water plus three of the twelve other drinks, so every test drink rests on roughly 17 people. The index repeats to a coefficient of variation of about 18%, which is around 180 mL of urine. Gaps smaller than that — cola at 1.23 against iced tea at 1.07, say — are noise, and the paper never compared one drink with another.1

  • Corrected for water content, the list gets shorter

    A litre of orange juice is not a litre of water: it is 89% water. Correct each drink for what it actually carries and orange juice falls from 1.39 to 1.24 and stops being significantly above water, while both milks and the rehydration solution stay above it. Its four-hour urine was not significantly lower than water's either (P=0.06).1

  • Rested, already-hydrated young men

    Everyone in the trial was healthy, fasted, euhydrated and aged 18 to 35. Older adults handle a fluid load differently: in the trial that repeated the protocol in two age groups, older adults retained more of every drink, including plain water, and the authors suggested a four-hour index would suit them better.5

  • Post-exercise numbers are a different measurement

    Retention percentages from studies where people sweat off 2% of their body mass and then drink 150% of it back are not hydration index values, and the two must never be read on the same scale. Milk retained 69% against water's 36% in one such trial — a real result about replacing losses, not a bigger version of the number on the chart.16

  • Almost all of this research is industry funded

    The index study was funded by the European Hydration Institute, whose Scientific Advisory Board its first author chairs. Others in the table below were paid for by Coca-Cola, Dairy Management, Liquid I.V., Nuun, Lingtea, QCK and the Almond Board. That does not make any of them wrong, but it is why each study's funder is printed next to its result rather than left in a footnote.1

What the guidelines actually count — and where more stops helping

  • Strong evidenceGuideline

    The NHS says drinks besides water count toward fluid intake, naming water, lower-fat milk and sugar-free drinks including tea and coffee, and recommends 6 to 8 cups or glasses a day.20

    6 to 8 cups or glasses a day; in pregnancy, caffeine no more than 200 mg a day.

    Caveat: The NHS does not say every drink counts: it steers away from sugary drinks and caps juice and smoothies at 150 ml a day. The page's review is overdue.

  • Strong evidenceGuideline

    EFSA counts water from drinking water, beverages of all kinds and food moisture toward total water intake, and leaves which beverages to prefer to national food-based dietary guidelines.18

    Adequate intake 2.0 L a day for women and 2.5 L for men.

  • Strong evidenceGuideline

    NASEM counts drinking water, water in beverages and water in food toward total intake, and says caffeinated drinks contribute much like non-caffeinated ones. On alcohol it describes a diuresis followed by an antidiuretic phase, and concludes the effect is transient with no appreciable 24-hour fluid loss.19

    Caveat: NASEM makes no explicit statement that all drinks count equally; do not paraphrase it that way.

  • Strong evidenceGuideline

    The CDC says daily water intake comes mostly from water and other beverages, with water-rich foods adding to it, and gives no single numeric target.21

    No numeric intake target; caffeine up to 400 mg a day.

    Caveat: Read through a summarising fetch tool, so re-check the wording. The CDC also says sodas, fruit drinks, sports drinks, energy drinks and sweetened coffee and tea carry calories with little nutritional value.

  • Strong evidenceGuideline

    NASEM set no upper limit for water because healthy kidneys excrete the excess, but notes that water toxicity has happened when people drank far faster than the kidney can excrete.19

    Kidney maximal excretion rate about 0.7 to 1.0 L an hour; no Tolerable Upper Intake Level set. NASEM defines hyponatremia as below 135 mmol/L, usually symptomatic below 130.

    Caveat: The excretion rate is a population figure, not a personal threshold.

  • Strong evidenceGuideline

    NATA defines exercise-associated hyponatremia as blood sodium below 135 mmol/L, caused by drinking hypotonic fluids, including sports drinks, beyond sweat losses.22

    Serum sodium below 135 mmol/L during or within 24 h of activity; typically symptomatic below 130 mmol/L; associated with maintained or increased body weight during exercise of an hour or more.

    Caveat: The 2015 international consensus statement could not be opened.

The ingredients people ask about

Caffeine, alcohol and sugar

Three ingredients explain nearly every question people arrive with, and a fourth one about bubbles that will not go away.

  • Caffeine

    The caffeinated drinks in the trial carried 96 to 212 mg of caffeine and changed nothing about net fluid balance. Coffee scored 0.91 and tea 1.03 hot and 1.07 iced, none of them separable from water.1

    • — The review those authors cite puts the threshold for a measurable diuretic effect at about 250 to 300 mg — two to three cups of coffee, or five to eight cups of tea.23
    • — A later trial by the same group added caffeine to a litre of drink at up to 400 mg/L and found no effect on urine output (p=0.83). Sucrose and sodium, in the same experiment, did change retention.4
    • — Pooled across 16 studies, caffeine at rest raised urine by roughly 120 mL (effect size 0.54, 95% CI 0.22 to 0.85), and the effect disappeared during exercise. Doses there ran to 741 mg — far above a mug.24
    • — EFSA's 400 mg a day for healthy adults is a safety limit, not a hydration threshold, and the figure is lower in pregnancy. Our caffeine calculator does the per-drink arithmetic.17

  • Alcohol

    Lager scored 0.99: a litre of it, drunk at rest by already-hydrated men, left about as much urine as a litre of water. That is the narrowest finding on this page, and it is not a reason to drink.1

    • — The paper never reported the lager's alcohol content, so the one number here comes without the detail that would make it useful.1
    • — In older men given 30 g of alcohol, 5% beer did not raise four-hour urine output (effect size -0.02) while wine (0.25) and spirits (0.18) did. At 24 hours, nothing differed. Three of that study's authors worked for the Dutch Beer Institute.25
    • — NASEM describes alcohol's diuresis as transient, with no appreciable 24-hour fluid loss. The textbook explanation — that ethanol suppresses vasopressin — is disputed by studies that measured the hormone and found no difference.19,25
    • — Water Goose has no alcohol preset, so beer is a row on this page and nothing else. If you are drinking, the drink to have alongside it is water.

  • Sugar

    Sugar is the biggest difference between the drinks in the table, and it barely shows up in the index. Cola scored 1.23 and orange juice 1.39 — but correct each for its own water content and orange juice drops to 1.24, no longer above water.1

    • — Concentrated sugar slows the stomach: a 188 g/L glucose drink took 130 ± 18 minutes to half-empty against 17 ± 1 minutes for a 40 g/L one. Fluid sitting in the stomach has not hydrated you yet.26
    • — At rest, 10% and 20% sucrose drinks left less urine than 0% or 5% ones. That is retention measured over four hours, not faster absorption.4
    • — A 250 mL glass carries about 26 g of sugars as cola, 21.4 g as orange juice and 30.6 g as lemonade. Water carries none.2
    • — The NHS caps fruit juice and smoothies at one small 150 ml glass a day, taken with a meal, on sugar grounds rather than hydration ones.20

  • Bubbles

    Sparkling water scored 0.98, which is water. Carbonation is the question people ask most often about this table and the one the data answers most flatly.1

    • — In people mildly dehydrated and then drinking freely for three hours, sodium raised retention to 68.3% against 53.7% for plain water, while carbonated water managed 42.5%. Carbonation did not improve retention, and both fizzy drinks caused more stomach discomfort.14
    • — That trial was funded by ITO EN, a drinks company, and seven of its thirteen authors are employees.14

Questions

Drinks and hydration, question by question

What is the most hydrating drink?

In the only trial that put thirteen drinks through the same protocol, skimmed milk had the highest mean two-hour hydration index at 1.58, with an oral rehydration solution at 1.54 and full-fat milk at 1.50, against 1.00 for still water. Read that carefully: every drink was compared with a pooled water arm and never with another drink, about 17 people drank each one, and the measurement covers two to four hours in rested, already-hydrated young men. It ranks how long a litre stays in you, not what is sensible to drink all day.1

What can I drink instead of water to stay hydrated?

Most of what you already drink. Eight of the twelve drinks tested — coffee, hot tea, iced tea, cola, diet cola, a sports drink, sparkling water and lager — were statistically indistinguishable from water over four hours. The NHS names water, lower-fat milk and sugar-free drinks including tea and coffee among the drinks that count toward fluid intake, and EFSA counts water from beverages of all kinds toward total intake. What separates these drinks is not the water they deliver but everything carried with it: sugar, caffeine, calories and alcohol.1,20,18

What is the beverage hydration index?

One number from one protocol: urine produced after a litre of still water, divided by urine produced after a litre of the test drink, measured two hours after drinking ended. Above 1.00 means more of the drink stayed in you. It comes from a 2016 trial in which 72 healthy men drank a litre over 30 minutes and had urine collected hourly for four hours. Its repeatability is a coefficient of variation of about 18%, roughly 180 mL, which is why small gaps between drinks on the chart mean very little.1

Do coffee and tea count towards your water intake?

Yes. Black coffee scored 0.91 and tea 1.03 hot and 1.07 iced, none of them different from still water, and those drinks carried 96 to 212 mg of caffeine with no effect on net fluid balance. The review the authors cite puts the threshold for a measurable diuretic effect at about 250 to 300 mg, and NASEM concluded that caffeinated drinks contribute to daily water intake much as non-caffeinated ones do. Our posts on coffee and on tea go through the rest of it.1,23,19

Which drinks here have no hydration index at all?

Ten of the twenty-three rows in the table were never put through this protocol. The trial measured thirteen drinks; soup, smoothies, lemonade and coconut water have no resting index, so nothing on this page ranks them by one. Electrolyte powders and tablets are missing for a duller reason -- USDA has no entry for drink mixes, so that row carries no composition either. A blank cell means nobody has measured it, not that the drink did badly.1,2

Does beer hydrate you?

A litre of lager, drunk at rest by already-hydrated men, left about as much urine as a litre of water: an index of 0.99. That is a measurement, not a recommendation. In older men, 30 g of alcohol as 5% beer did not raise four-hour urine output while wine and spirits did, and no drink changed 24-hour output; NASEM describes alcohol's diuresis as transient, with no appreciable 24-hour fluid loss. Water Goose has no alcohol preset, and nothing on this page is a reason to drink beer for hydration.1,25,19

Is coconut water or a sports drink more hydrating than water?

The sports drink in the trial scored 1.02, which is water with extra steps as far as retention goes. Coconut water has never been through this protocol, so it has no index at all; the post-exercise trials that tested it found retention much like a sports drink's. The one electrolyte drink that clearly beat water was the oral rehydration solution at 1.54, and it carried 55 mmol/L of sodium against the sports drink's 21.1,27

Should I swap my water for milk or juice?

No, and the trial does not suggest it. The measurement covers a two-to-four-hour window after a single litre, in rested young men who were already hydrated, and no study has compared drinks across a full day. The milk in that trial carried 640 kcal per litre and the orange juice 470, against none for water — and orange juice stopped being significantly better than water once each drink was corrected for its own water content. The useful reading of this table is not that you should stop drinking water. It is that the other things you drink are already counting.1

Receipts

Sources and how we compiled this

Where the composition comes from

U.S. Department of Agriculture, Agricultural Research Service. FoodData Central. Built 2026-09-15 from the published CSV releases, never hand-typed. Every drink uses USDA’s generic entry, not a brand’s label.

  • Food and Nutrient Database for Dietary Studies (FNDDS) · 2024-10-31
  • — Drinks and prepared foods use FNDDS (foods and drinks as consumed) whenever FNDDS has a code for the item.
  • — Raw produce and dairy foods use Foundation Foods when the entry is current (listed in foundation_food.csv), stands for the food generally rather than one cultivar or colour, and reports water, energy and potassium, plus fiber for plant foods. Otherwise SR Legacy.
  • — A Foundation pick with no household portions uses the portions of the SR Legacy entry for the same food (portionsSource).
  • — Fluid milks use FNDDS, whose composition matches the Foundation analyses (crossCheck) and which has consistent drink portions.
  • — SR Legacy fills any remaining gap. No proxy is used where USDA has no sensible entry (see missing).

What this evidence cannot tell you

  • — The Beverage Hydration Index measures short-term retention, not 24-h hydration: for each person it is urine after still water divided by urine after the test drink, anchored 2 h after drinking 1 L over 30 min.
  • — Most participants were young, healthy, euhydrated, fasted, rested men given a single 1 L dose. Older adults retain more water and respond differently.
  • — Post-exercise retention percentages come from dehydrated people drinking 100-150% of the body mass they lost. They are not comparable to BHI values and must not share a scale with them.
  • — Clarke 2019 reports mean ± SEM while most studies report SD, so spreads are not directly comparable.
  • — No resting BHI data were found for soup, smoothie, lemonade or coconut water. Energy-drink evidence comes from one modified-protocol study, and soda evidence is cola and diet cola from Maughan 2016 only.
  • — Many of these studies are industry funded: the European Hydration Institute, Entrinsic, Dairy Management, Nuun, Coca-Cola, Buoy, Lingtea, QCK, the Almond Board, 8 POiNT, VitaCoco, Liquid I.V., Innate-Essence and ITO EN all appear as funders.
  • — Commercial formulations change over time. Compositions are as measured or labelled at the time of each study and are not current labels.

Who paid for the research

Hydration research is heavily industry funded. That does not make a study wrong, but you should know who paid before you weigh it. Water Goose took no money from anyone named here, and no brand saw this page before it went up.

  • — Maughan 2016: Funded by a grant from the European Hydration Institute (EHI). Prof Maughan chairs the EHI Scientific Advisory Board (not the Institute itself); Dr Watson has also received EHI funding.
  • — Clarke 2019: Partially funded by an unrestricted gift from Entrinsic Health Solutions.
  • — Berry 2020: Funded by Dairy Management Inc.
  • — Pence 2020: Provided in part by Nuun & Company, Inc., and the University of Memphis.
  • — Millard-Stafford 2021: Funded by Coca-Cola.
  • — Bechke 2022: Funded by QCK, LLC (grant 20-0081), the maker of HOIST.
  • — Yun 2022: Grants from Lingtea Co., Ltd., which makes the oral rehydration solution and one of the sports drinks tested.
  • — Millard-Stafford 2025: Funded by Liquid-IV, a Unilever company (grant GR00027334), maker of the Liquid I.V. Energy Multiplier that matched water in the trial. A Liquid IV principal scientist helped conceptualise and review the manuscript. The first author has also had funding from Coca-Cola, Kraft and Liquid IV.
  • — Boyd-Shiwarski 2025: Buoy paid for part of two authors' time.
  • — Takamata 2026: Funded by ITO EN, Ltd.; seven of the thirteen authors are ITO EN employees.
  • — Juett 2026: Innovate UK Knowledge Transfer Partnership with Innate-Essence, maker of the juice tested. The senior author has PepsiCo research funding.
  • — Polhuis 2017: Three authors (Polhuis, Wijnen, Sierksma) were employed by the Dutch Beer Institute.
  • — Kalman 2012: Financial support provided by the VitaCoco Company.

References

Every number on this page points at one of these.

  1. 1

    Maughan RJ, Watson P, Cordery PAA, Walsh NP, Oliver SJ, Dolci A, Rodriguez-Sanchez N, Galloway SDR. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. Am J Clin Nutr 2016;103(3):717-723.

    StudyRead: full textOpen source

    Funding: Funded by a grant from the European Hydration Institute (EHI). Prof Maughan chairs the EHI Scientific Advisory Board (not the Institute itself); Dr Watson has also received EHI funding.

    Read from the LJMU green open-access accepted manuscript (https://researchonline.ljmu.ac.uk/id/eprint/12468/); the publisher page was blocked. ISRCTN13014105.

  2. 2

    U.S. Department of Agriculture, Agricultural Research Service. FoodData Central (SR Legacy and Foundation Foods).

    DatasetRead: official pageOpen source

    Water content is not the same thing as a net hydration effect.

  3. 3

    Sollanek KJ, Tsurumoto M, Vidyasagar S, Kenefick RW, Cheuvront SN. Neither body mass nor sex influences beverage hydration index outcomes during randomized trial when comparing 3 commercial beverages. Am J Clin Nutr 2018;107(4):544-549.

    StudyRead: abstractOpen source

    NCT03262597. Full text blocked; the abstract does not state the BHI time window, and drink composition is known only from later papers.

  4. 4

    Maughan RJ, Watson P, Cordery PAA, Walsh NP, Oliver SJ, Dolci A, Rodriguez-Sanchez N, Galloway SDR. Sucrose and sodium but not caffeine content influence the retention of beverages in humans under euhydrated conditions. Int J Sport Nutr Exerc Metab 2019;29(1):51-60.

    StudyRead: abstractOpen source

    Abstract describes a double-blind crossover design. Numeric BHI values are not in the abstract. Peden 2024 describes the sucrose result differently (only the 20% drink raising BHI).

  5. 5

    Clarke MM, Stanhewicz AE, Wolf ST, Cheuvront SN, Kenefick RW, Kenney WL. A randomized trial to assess beverage hydration index in healthy older adults. Am J Clin Nutr 2019;109(6):1640-1647.

    StudyRead: full textOpen source

    Funding: Partially funded by an unrestricted gift from Entrinsic Health Solutions.

    NCT03559101. Data reported as mean ± SEM, not SD.

  6. 6

    Berry CW, Wolf ST, Murray B, Kenney WL. Hydration efficacy of a milk permeate-based oral hydration solution. Nutrients 2020;12(5):1502.

    StudyRead: full textOpen source

    Funding: Funded by Dairy Management Inc.

  7. 7

    Pence J, Bloomer RJ. Impact of Nuun electrolyte tablets on fluid balance in active men and women. Nutrients 2020;12(10):3030.

    StudyRead: full textOpen source

    Funding: Provided in part by Nuun & Company, Inc., and the University of Memphis.

  8. 8

    Millard-Stafford M, Snow TK, Jones ML, Suh H. The beverage hydration index: influence of electrolytes, carbohydrate and protein. Nutrients 2021;13(9):2933.

    StudyRead: full textOpen source

    Funding: Funded by Coca-Cola.

  9. 9

    Bechke EE, Zaplatosch ME, Choi JY, Adams WM. Nutrients 2022;14(6):1286.

    StudyRead: full textOpen source

    Funding: Funded by QCK, LLC (grant 20-0081), the maker of HOIST.

    Isotonic beverage (HOIST) versus water; the full title was not recorded in the evidence file.

  10. 10

    Yun HJ, Lee JY, Jeon M, Oh SE, Park JH, Yoon J. The effects of fluid absorption and plasma volume changes in athletes following consumption of various beverages. BMC Sports Sci Med Rehabil 2022;14(1):207.

    StudyRead: full textOpen source

    Funding: Grants from Lingtea Co., Ltd., which makes the oral rehydration solution and one of the sports drinks tested.

  11. 11

    Millard-Stafford M, Hack B, Harp A, Smith E. Caffeinated Energy Drink Formulations Differentially Impact Hydration Versus Water: Does Habitual Caffeine Intake or Biological Sex Matter? Nutrients 2025;17(18):2913.

    StudyRead: full textOpen source

    Funding: Funded by Liquid-IV, a Unilever company (grant GR00027334), maker of the Liquid I.V. Energy Multiplier that matched water in the trial. A Liquid IV principal scientist helped conceptualise and review the manuscript. The first author has also had funding from Coca-Cola, Kraft and Liquid IV.

    Modified protocol: 500 mL of test drink plus 500 mL of water, not 1 L of drink.

  12. 12

    Boyd-Shiwarski CR, Ray EC, Subramanian H, Zharichenko N, Monroe A, Mahajan A. Nutrients 2025;17(3):585.

    StudyRead: full textOpen source

    Funding: Buoy paid for part of two authors' time.

    Electrolyte drops vs tablets and the beverage hydration index; the full title was not recorded in the evidence file. NCT05768789. Non-randomised, fixed visit order.

  13. 13

    Rodriguez-Sanchez N, Galloway SDR. A randomised trial to assess fluid and electrolyte balance responses following ingestion of different beverages in young and older men. Eur J Appl Physiol 2023;123(10):2331-2340.

    StudyRead: full textOpen source

    Same urine protocol as the BHI, but drinks taken over 60 min and no BHI calculated.

  14. 14

    Takamata A, Kosugi N, Sakagawa N, et al. Effects of Carbonated and Electrolyte-Added Water on Body Fluid Regulation and Ingestive Behavior During Ad Libitum Rehydration Following Mild Hypohydration. Nutrients 2026;18(12):1846.

    StudyRead: full textOpen source

    Funding: Funded by ITO EN, Ltd.; seven of the thirteen authors are ITO EN employees.

  15. 15

    Juett LA, van der Wolf-Ong J, Gyamfi PA, et al. Post-exercise rehydration: a randomized cross-over trial comparing a 100% fruit juice, a glucose-based sports drink, and water. J Int Soc Sports Nutr 2026;23(1):2721140.

    StudyRead: full textOpen source

    Funding: Innovate UK Knowledge Transfer Partnership with Innate-Essence, maker of the juice tested. The senior author has PepsiCo research funding.

    The juice was Raw Hydrate (watermelon, pomegranate and lime), not orange juice; the sports drink was Lucozade Sport.

  16. 16

    Shirreffs SM, Watson P, Maughan RJ. Milk as an effective post-exercise rehydration drink. Br J Nutr 2007;98(1):173-180.

    StudyRead: full textOpen source

    The paper calls the milk 'low-fat milk (0.2% fat)'. Its abstract lists the water and sports-drink urine volumes in reverse order; evidence.ts uses the Results.

  17. 17

    EFSA NDA Panel. Scientific Opinion on the safety of caffeine. EFSA Journal 2015;13(5):4102.

    GuidelineRead: official pageOpen source

    Figures are from EFSA's caffeine topic page; the full opinion returned 403. These are safety limits, not hydration thresholds.

  18. 18

    EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). Scientific Opinion on Dietary Reference Values for water. EFSA Journal 2010;8(3):1459.

    GuidelineRead: full textOpen source

    Read from the DTU Orbit copy of the published PDF; Wiley was blocked.

  19. 19

    Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Chapter 4: Water. Washington, DC: The National Academies Press; 2005.

    GuidelineRead: full textOpen source

    Cite this directly for adequate intakes: Maughan 2016's introduction misstates the women's figure. On alcohol it concludes the diuresis is transient; it makes no explicit 'all drinks count equally' statement.

  20. 20

    NHS. Water, drinks and your health.

    GuidelineRead: official pageOpen source

    Page last reviewed 17 May 2023; next review was due 17 May 2026, so the review is overdue as of September 2026.

  21. 21

    Centers for Disease Control and Prevention. Water and Healthier Drinks. Last reviewed 5 March 2026.

    GuidelineRead: official pageOpen source

    Read through a summarising fetch tool; do a verbatim check before quoting its wording.

  22. 22

    McDermott BP, Anderson SA, Armstrong LE, et al. National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active. J Athl Train 2017;52(9):877-895.

    GuidelineRead: full textOpen source

  23. 23

    Maughan RJ, Griffin J. Caffeine ingestion and fluid balance: a review. J Hum Nutr Diet 2003;16(6):411-420.

    StudyRead: abstractOpen source

    Narrative review; the source of Maughan 2016's 250-300 mg threshold.

  24. 24

    Zhang Y, Coca A, Casa DJ, Antonio J, Green JM, Bishop PA. Caffeine and diuresis during rest and exercise: a meta-analysis. J Sci Med Sport 2015;18(5):569-574.

    StudyRead: full textOpen source

    Caffeine sources in the pooled studies were mixed: pills, tea, coffee and caffeinated beverages.

  25. 25

    Polhuis KCMM, Wijnen AHC, Sierksma A, Calame W, Tieland M. The Diuretic Action of Weak and Strong Alcoholic Beverages in Elderly Men: A Randomized Diet-Controlled Crossover Trial. Nutrients 2017;9(7):660.

    StudyRead: full textOpen source

    Funding: Three authors (Polhuis, Wijnen, Sierksma) were employed by the Dutch Beer Institute.

  26. 26

    Vist GE, Maughan RJ. The effect of osmolality and carbohydrate content on the rate of gastric emptying of liquids in man. J Physiol 1995;486(Pt 2):523-531.

    StudyRead: abstractOpen source

    Values are mean ± SEM.

  27. 27

    Kalman DS, Feldman S, Krieger DR, Bloomer RJ. Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. J Int Soc Sports Nutr 2012;9:1.

    StudyRead: full textOpen source

    Funding: Financial support provided by the VitaCoco Company.

This page describes what studies measured in healthy adults. It is general wellness information, not medical advice, diagnosis or treatment. Fluid needs change with health conditions, medication and pregnancy — and some conditions require drinking less. Talk to a clinician about yours.

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