Does drinking water lower blood pressure?

No trial shows that it does. In a 2023 meta-analysis, three randomized trials in 32 healthy people found that a quick drink of 12 to 17 fl oz (350 to 500 mL) of water raised blood pressure slightly, by 2.33 mmHg systolic and 2.73 mmHg diastolic. The one trial that asked people to drink 51 fl oz (1500 mL) more a day for 6 months found no significant change in blood pressure. What is in the water may matter as well: saltier drinking water goes with higher pressure in observational studies.

Myth. Drinking more water is not a treatment for high blood pressure. The randomized evidence points the other way in the short term, a small rise, and shows no change over months.

What the trials found

A glass of water raises pressure for a while

Drinking water quickly triggers a short rise in blood pressure. A 2023 meta-analysis pooled the three most rigorous randomized trials in healthy people, 32 in all, given 12 to 17 fl oz (350 to 500 mL) at once. Systolic pressure rose by 2.33 mmHg (95% CI 1.02 to 3.64) and diastolic by 2.73 mmHg (95% CI 1.15 to 4.30). These are short-term peaks after a single drink. They say nothing about drinking more every day for weeks.

In people with orthostatic hypotension, whose pressure drops when they stand, the same meta-analysis found a far larger rise: 24.18 mmHg systolic (95% CI 15.48 to 32.88) and 11.98 mmHg diastolic. Those data come mostly from before-and-after studies, and the results varied a great deal between them, so the size is uncertain. The direction is the same: up.

Fluid around exercise behaves similarly. A 2023 meta-analysis of 33 studies, mixing randomized and non-randomized designs, found that drinking water or sports drinks before, during or after exercise left systolic pressure 2.25 mmHg higher than no fluid (95% CI 0.08 to 4.42), with no effect on diastolic pressure.

Drinking more every day

A 2024 systematic review gathered 18 randomized trials that changed how much water people drank each day. It did not pool them, and it reports three findings on blood pressure. In one trial in 20 healthy people, an extra 2 tbsp (30 mL) of water per kilogram of body weight a day raised daytime mean arterial pressure from 89.0 to 91.4 mmHg, with night-time pressure unchanged. In young adults with low blood pressure, more water was linked to higher daytime pressure. In the one trial that ran for 6 months, 51 fl oz (1500 mL) more water a day did not change blood pressure, blood sodium or kidney filtration to a statistically significant degree.

Unsettled. One small trial is the source of the idea that water lowers pressure. In 55 healthy Japanese adults who drank two extra 19 fl oz (550 mL) bottles a day for 12 weeks, systolic pressure in the water group fell from 123.8 to 117.4 mmHg. That is a change within one group over time, not a difference against the group that drank as usual. The trial was open label, and its main outcome, blood sugar, did not change. It is a reason for a better trial, not an answer.

What is in the water

Sodium in drinking water is linked to higher pressure across many observational studies. A 2025 meta-analysis of 27 observational studies in 74,063 people, mostly coastal communities such as those in Bangladesh, found that people drinking saltier water had systolic pressure 3.22 mmHg higher (95% CI 1.11 to 5.33) and diastolic pressure 2.82 mmHg higher. Their odds of hypertension were 26 percent higher (odds ratio 1.26, 95% CI 1.07 to 1.48). That odds ratio fell to 1.15 and lost significance in a sensitivity analysis, and these are associations from salty groundwater, not from ordinary tap water.

Sodium in a different form may behave differently. In a 28-day randomized trial of 94 adults drinking 1.6 to 2.1 quarts (1.5 to 2 liters) a day, mineral water high in sodium and bicarbonate did not change blood pressure differently from low-sodium mineral water. The extra sodium was excreted.

For the rest of what is known about water, including the one hard outcome it has been tested on, see the water page.

Who should be careful

Not for everyone. If you have heart failure, drinking more water to help your blood pressure is the wrong move. The European Society of Cardiology Heart Failure Association advises keeping salt to no more than 5 g a day in heart failure and considers limiting fluid to 1.6 to 2.1 quarts (1.5 to 2 liters) a day in selected patients. How much you drink is a question for whoever treats you.

Babies are the clearest case where the water matters. In a randomized study of 58 formula-fed newborns, formula made up with high-sodium tap water at 196 mg per liter gave higher blood pressure from week 6 to week 8 than formula made with low-sodium water at 32 mg per liter. That was a small study, and it is about infant formula, not adults.

If you live where groundwater is salty, the observational data above are about you more than about anyone else. For healthy adults, the 12-week trial of an extra 1.2 quarts (1.1 liters) a day reported no adverse events from the extra water. That trial did not include people with heart or kidney disease.

What expert bodies say

We found no expert body, among the American Heart Association, the European Society of Cardiology, WHO or NICE, that names drinking water as a treatment for high blood pressure. The one expert statement in the evidence for this page goes in the other direction for a specific group. The European Society of Cardiology Heart Failure Association considers fluid restriction to 1.6 to 2.1 quarts (1.5 to 2 liters) a day in selected patients with heart failure, alongside a salt limit of 5 g a day.

How we searched

What would change this answer

• A randomized trial of extra plain water in people with high blood pressure, with 24-hour ambulatory blood pressure as the outcome and a comparison between groups. The 2024 review of 18 trials found none, and neither did our web search.
• A repeat of the 12-week Japanese trial with blinding where possible and blood pressure as the main outcome, so that the fall it reported can be tested against the control group.
• Trials in places with salty groundwater that swap in low-sodium water and measure blood pressure. That would turn the observational link into a tested effect.

Sources

1. ev-wbp-01 · Meta-analysis or systematic review · systematic review and meta-analysis of 5 RCTs and 12 prospective cohort studies; RCT subgroup of healthy participants · n = 32
   Similarly, the 3 rigorous RCTs (Figure 4A and 4B) including healthy participants (n=32) reported increases in both SBP (MD, 2.33 [95% CI, 1.02–3.64]; I 2=0%) and DBP (MD, 2.73 [95% CI, 1.15–4.30]; I 2=56%).
   
   Who: healthy participants given a rapid 12-17 fl oz (350-500 mL) water bolus, seated or supine
   Effect: SBP MD +2.33 mmHg (95% CI 1.02 to 3.64); DBP MD +2.73 mmHg (95% CI 1.15 to 4.30); short-term maximum effect
   Certainty: Three small RCTs, short-term effect after a bolus; not about daily drinking for weeks.
   Journal of the American Heart Association, 2023, Hemodynamic Effects of the Osmopressor Response: A Systematic Review and Meta-Analysis · checked 2026-10-07 · we read the fulltext
2. ev-wbp-02 · Observational data · meta-analysis pooling mostly prospective cohort (before-after) studies in orthostatic hypotension · n = —
   In participants with OH (Figure 3A and 3B), the intervention was found to substantially increase both SBP (MD, 24.18 [95% CI, 15.48–32.88]) and DBP (MD, 11.98 [95% CI, 8.87–15.09]).
   
   Who: patients with orthostatic hypotension, including multiple system atrophy and pure autonomic failure
   Effect: SBP MD +24.18 mmHg (95% CI 15.48 to 32.88); DBP MD +11.98 mmHg (95% CI 8.87 to 15.09); heterogeneity I2 94% and 86%
   Certainty: Mostly before-after cohorts, high heterogeneity; level by the design of the primary studies.
   Journal of the American Heart Association, 2023, Hemodynamic Effects of the Osmopressor Response: A Systematic Review and Meta-Analysis · checked 2026-10-07 · we read the fulltext
3. ev-wbp-03 · Randomized controlled trial(s) · systematic review of 18 RCTs of changed daily water intake, narrative synthesis · n = 20
   In 20 healthy individuals without hypotension or hypertension,14 drinking an additional 30 mL water per kilogram of body weight per day was associated with increased daytime mean (SD) arterial blood pressure from 89.0 (5.5) to 91.4 (6.4) mm Hg (P = .005) while night-time blood pressure remained unchanged compared with the control group.
   
   Who: healthy individuals without hypotension or hypertension
   Effect: daytime mean arterial pressure 89.0 (SD 5.5) to 91.4 (SD 6.4) mmHg, P = .005; night-time BP unchanged vs control
   Certainty: A single small study inside a review; without pooling.
   JAMA Network Open, 2024, Outcomes in Randomized Clinical Trials Testing Changes in Daily Water Intake: A Systematic Review · checked 2026-10-07 · we read the fulltext
4. ev-wbp-04 · Randomized controlled trial(s) · systematic review of 18 RCTs of changed daily water intake, narrative synthesis · n = 1 trial
   Lastly, one study27 did not find a statistically significant association between increased daily water intake (by 1500 mL for 6 months) and blood sodium, blood pressure, glomerular filtration rate, or quality of life score (assessed by 36-Item Short Form Survey).
   
   Who: adults randomized to increase daily water intake by 51 fl oz (1500 mL) for 6 months
   Effect: no statistically significant change in blood pressure, blood sodium, GFR or quality of life
   Certainty: The only long RCT in the review with BP as an outcome.
   JAMA Network Open, 2024, Outcomes in Randomized Clinical Trials Testing Changes in Daily Water Intake: A Systematic Review · checked 2026-10-07 · we read the fulltext
5. ev-wbp-05 · Meta-analysis or systematic review · systematic review of 18 RCTs of changed daily water intake, narrative synthesis · n = —
   RCTs of interventions involving increased daily water intake found that increased intake was associated with increased mean daytime arterial blood pressure in young adults with hypotension.
   
   Who: young adults with hypotension
   Effect: increased mean daytime arterial blood pressure with increased daily water intake
   Certainty: A descriptive conclusion of the review based on one or two RCTs.
   JAMA Network Open, 2024, Outcomes in Randomized Clinical Trials Testing Changes in Daily Water Intake: A Systematic Review · checked 2026-10-07 · we read the fulltext
6. ev-wbp-06 · Randomized controlled trial(s) · open-label two-arm randomized controlled trial, 12 weeks, two extra 19 fl oz (550 mL) bottles of water a day vs habitual intake · n = 55
   The systolic blood pressure (SBP) in the intervention group decreased over time from Week 0 to Week 12, from 123.8 ± 20.5 to 117.4 ± 15.7 mmHg (mean ± SD, p = 0.01) (Figure 5a).
   
   Who: healthy Japanese adults with fasting glucose 90-125 mg/dL
   Effect: SBP 123.8 ± 20.5 to 117.4 ± 15.7 mmHg within the intervention group, p = 0.01; diastolic BP unchanged; fluid intake 1.3 to 2.0 L/day
   Certainty: Change within the group, not a difference between groups; open-label design; the primary endpoint (glucose) did not change.
   Nutrients, 2020 · checked 2026-10-07 · we read the fulltext
7. ev-wbp-07 · Randomized controlled trial(s) · open-label two-arm randomized controlled trial, 12 weeks, two extra 19 fl oz (550 mL) bottles of water a day vs habitual intake · n = 55
   No adverse events due to the intervention were observed in this study.
   
   Who: healthy Japanese adults with fasting glucose 90-125 mg/dL
   Effect: no intervention-related adverse events in healthy adults over 12 weeks
   Certainty: Healthy adults; does not apply to heart failure or kidney disease.
   Nutrients, 2020 · checked 2026-10-07 · we read the fulltext
8. ev-wbp-08 · Meta-analysis or systematic review · systematic review and meta-analysis with meta-regression of randomized and non-randomized trials · n = 33 studies in meta-analysis
   The values of the SBP were higher than those of the controls (2.25 mmHg, 95%CI: 0.08 to 4.42).
   
   Who: adults over 18 drinking water or isotonic drinks before, during or after exercise vs no fluid
   Effect: SBP +2.25 mmHg (95% CI 0.08 to 4.42); no effect on DBP; HR during exercise -6.20 bpm
   Certainty: Physical exercise context; mixed designs.
   Nutrients, 2023 · checked 2026-10-07 · we read the abstract
9. ev-wbp-09 · Observational data · systematic review and meta-analysis of observational studies (Newcastle-Ottawa Scale) · n = 27 studies, 74 063 participants
   Briefly, the pooled MD (95% CIs) was 3.22 mm Hg (1.11 to 5.33) for SBP, and was 2.82 mm Hg (1.44 to 4.20) for DBP (figures2 3).
   
   Who: general and coastal populations in 7 countries, higher vs lower drinking water salinity
   Effect: SBP MD +3.22 mmHg (95% CI 1.11 to 5.33); DBP MD +2.82 mmHg (95% CI 1.44 to 4.20), higher vs lower salinity
   Certainty: Observational data, mostly coastal communities (Bangladesh, etc.); about saline water, not ordinary drinking water.
   BMJ Global Health, 2025, Association of drinking water salinity with elevated blood pressure and risk of hypertension among coastal and other populations: a systematic review and meta-analysis of observational studies · checked 2026-10-07 · we read the fulltext
10. ev-wbp-10 · Observational data · systematic review and meta-analysis of observational studies (Newcastle-Ottawa Scale) · n = 27 studies, 74 063 participants
    High versus low water salinity was associated with an increased risk of hypertension: pooled OR (95% CI) of 1.26 (1.07 to 1.48) (online supplemental appendix 7).
    
    Who: general and coastal populations in 7 countries, higher vs lower drinking water salinity
    Effect: hypertension OR 1.26 (95% CI 1.07 to 1.48), higher vs lower salinity; OR 1.15 (0.94 to 1.42) in sensitivity analysis
    Certainty: Odds, not risk; sensitivity to a single study.
    BMJ Global Health, 2025, Association of drinking water salinity with elevated blood pressure and risk of hypertension among coastal and other populations: a systematic review and meta-analysis of observational studies · checked 2026-10-07 · we read the fulltext
11. ev-wbp-11 · Randomized controlled trial(s) · randomized prospective study, 8 weeks plus 24-week follow-up · n = 58
    From the age of 6 weeks until week 8, MAP, SBP and DBP were found to be significantly greater in the group 2 (HSTW).
    
    Who: term infants on milk formula diluted with low-sodium mineral water or high-sodium tap water; breastfed controls
    Effect: MAP, SBP and DBP significantly greater in the high-sodium water group from week 6 to week 8
    Certainty: Small sample; sodium in water for formulas is not about adults.
    J Hypertens, 2002 · checked 2026-10-07 · we read the abstract
12. ev-wbp-12 · Randomized controlled trial(s) · randomized controlled intervention study, 28 days · n = 94
    The study revealed no significant differences in blood pressure changes between individuals consuming HBS water and LBS water.
    
    Who: adults drinking 1500-2000 mL/day mineral water
    Effect: no between-group difference in SBP, DBP or MAP after 28 days; extra sodium excreted
    Certainty: Short duration; sodium in the form of bicarbonate, not chloride.
    Blood Press, 2024 · checked 2026-10-07 · we read the abstract
13. ev-wbp-13 · Position of an expert body · clinical consensus statement · n = —
    Consequently, the European Society of Cardiology HF guidelines have gradually downgraded these recommendations over time, now advising for the limitation of salt intake to no more than 5 g/day in patients with HF, while contemplating fluid restriction of 1.5-2 L/day only in selected patients.
    
    Who: patients with acute and chronic heart failure
    Effect: fluid restriction 1.5-2 L/day in selected patients; salt no more than 5 g/day
    Certainty: For people with heart failure the advice "drink more" is not suitable without a doctor.
    Eur J Heart Fail, 2024 · checked 2026-10-07 · we read the abstract