Water Intake Recommendations for Passing Kidney Stones
To assist in passing a kidney stone, patients should drink enough fluid to produce at least 2-2.5 liters of urine per day, which typically requires consuming 3.5-4 liters (approximately 12-14 cups) of water daily. 1
Fluid Intake Guidelines
Recommended Volume
- Aim for 3.5-4 liters of total fluid intake daily 1, 2
- This volume is necessary to achieve the target urine output of at least 2-2.5 liters per day 1, 3
- Low-quality evidence from clinical trials shows that increased fluid intake to achieve more than 2 L of urine per day resulted in significantly less stone recurrence (12.1% vs. 27.0%) over a 60-month follow-up period 4
Timing and Consistency
- Distribute fluid intake throughout the day rather than consuming large amounts at once 1
- Maintain consistent hydration, especially after physical activity or in hot environments 1
- Continue high fluid intake even after passing the current stone to prevent recurrence 5
Types of Fluids
Water
- Plain water should be the primary source of fluid intake 4, 1
- Low-calcium mineral water (oligomineral water) may be slightly more beneficial than regular tap water, showing lower stone recurrence rates (17.0% vs. 22.9%) 4, 1
Other Beverages
- Avoid soft drinks, particularly colas containing phosphoric acid, as they increase stone risk 4, 1
- Coffee, tea, and citrus juices may provide additional benefits due to their citrate content, which inhibits stone formation 1
Additional Dietary Considerations
While increasing water intake is the primary intervention for passing kidney stones, these additional measures can help:
- Maintain normal calcium intake (1,000-1,200 mg/day) rather than restricting calcium 1, 2
- Reduce sodium intake to less than 2,300 mg/day 4, 1
- Limit animal protein consumption to 0.8-1.0 g/kg body weight/day 1, 2
- For calcium oxalate stones, limit intake of oxalate-rich foods while maintaining normal calcium consumption 4
Monitoring Effectiveness
- Monitor urine color - aim for pale yellow urine as an indicator of adequate hydration 1
- The goal is to produce dilute urine to reduce the concentration of stone-forming substances 6, 7
Common Pitfalls to Avoid
- Inadequate fluid intake: Many patients underestimate how much they need to drink
- Inconsistent hydration: Drinking large amounts at once rather than spreading throughout the day
- Relying on thirst: Thirst is not a reliable indicator of hydration needs for stone prevention
- Stopping increased fluid intake after passing the stone: Continued high fluid intake is essential for preventing recurrence
By maintaining adequate hydration with 3.5-4 liters of fluid daily to produce at least 2-2.5 liters of urine, patients can effectively facilitate the passage of kidney stones and reduce the risk of recurrence.