Yes, drinking extra water is strongly protective against kidney stone formation and recurrence.
Increased fluid intake is the single most important dietary intervention for preventing kidney stones, and all patients with a history of stones should be counseled to drink enough water to produce at least 2-2.5 liters of urine daily 1, 2.
The Evidence for Water Intake
The relationship between fluid intake and kidney stone formation is clear and well-established:
For stone recurrence prevention (secondary prevention): Increased water intake reduces stone recurrence by approximately 50-55% 1, 3. In the highest quality randomized trial, patients who increased their water intake to achieve at least 2 liters of urine output per day had a 55% lower risk of stone recurrence compared to those with standard water intake 3.
Time to recurrence is also prolonged: Patients drinking more water experience a 60% reduction in the hazard of stone recurrence, meaning stones take significantly longer to form when urine is adequately diluted 3.
The mechanism is straightforward: Higher fluid intake dilutes the concentration of stone-forming substances (calcium, oxalate, uric acid) in the urine, reducing supersaturation and crystal formation 2.
Specific Recommendations
Target Urine Volume
- Primary goal: Achieve at least 2.0-2.5 liters of urine output per day 1, 2
- For high-risk patients (primary hyperoxaluria, enteric hyperoxaluria, cystinuria): Target 3.5-4 liters of urine output daily 4
- To achieve 2.5 L urine output, most patients need to drink approximately 3-3.5 liters of fluid daily 5
How to Implement
- Spread fluid intake throughout the day AND night to avoid overnight urinary supersaturation 4
- The fluid of choice is plain water 1
- Tap water appears protective and may be preferable to bottled water 6
Beverage-Specific Guidance
Beneficial or neutral beverages (observational data):
- Coffee (caffeinated and decaffeinated)
- Tea
- Wine and moderate alcohol
- Orange juice and citrus juices
- Plain water 2, 7
Beverages to avoid or limit:
- Sugar-sweetened soft drinks increase stone risk 2, 7
- Colas and drinks with phosphoric acid specifically increase recurrence 1
- Drinks with high fructose content 4
Important Caveats
Contraindications exist: Patients with heart failure, end-stage renal disease, or other conditions where fluid restriction is medically necessary should NOT be advised to increase fluid intake 1.
Already adequate intake: Patients who already drink sufficient fluids to produce >2.5 L urine daily do not need to increase intake further 1.
Quality of evidence: While the recommendation is strong and guideline-supported, the underlying evidence is rated as low to moderate quality due to limited randomized trials 1, 3. However, the biological plausibility is extremely strong, side effects are minimal, and the intervention is low-cost.
Compliance is challenging: Many patients struggle to maintain high fluid intake long-term. Practical strategies include setting hourly drinking goals, using marked water bottles, and establishing drinking routines tied to daily activities 8.
Clinical Algorithm
For any patient with kidney stones:
- Assess current fluid intake and 24-hour urine volume (if available)
- If urine volume <2.0 L/day: Counsel to increase water intake with specific target of 2.5-3 L fluid intake daily
- Provide practical strategies: Drink water with each meal, keep water accessible, drink before bed and upon waking
- Monitor compliance: Follow-up 24-hour urine collection to verify urine volume goal is achieved
- If increased fluids alone fail to prevent recurrence: Add pharmacologic therapy (thiazides, citrate, or allopurinol) 1
The evidence is unequivocal: inadequate fluid intake is a modifiable risk factor for kidney stone formation, and increasing water consumption is protective for both initial stone formation and recurrence.