No measure lowers the risk of kidney stones as reliably and cheaply as drinking enough. But how much is enough – and how can you tell if you're getting it right? Here are the answers based on urology guidelines.
The goal: 2.5 liters of urine per day
The American Urological Association (AUA) guideline advises all stone formers to drink enough to produce at least 2.5 liters (about 85 oz) of urine per day. The more diluted the urine, the harder it is for crystals to form and grow. Because we also lose water through skin and breathing, for most people that means drinking roughly 2.5–3 liters (85–100 oz) – more in heat, during exercise or physical work.
The simple self-test: urine color
- Pale yellow to almost clear: well diluted – keep it up.
- Dark yellow: not enough fluid – have a large glass of water now.
- Note: B vitamins turn urine bright yellow even if you're well hydrated.
If you want to know exactly, measure your urine for one day with a measuring jug.
What to drink
- Water is the foundation – tap or mineral water.
- Lemon water: citrate inhibits stone formation – more in our article on lemon juice for kidney stones.
- Coffee and tea count too and are even linked to a slightly lower risk in studies.
- Avoid: sugar-sweetened drinks and cola – they are associated with more kidney stones.
How to reach your target
- Drink a large glass of water as soon as you get up.
- Keep a bottle with time markings within sight.
- Have a glass of water with every meal.
- One glass before bed – urine is most concentrated at night.
- During exercise and heat, add about 0.5–1 liter (17–34 oz) per hour.
More prevention strategies are in our guide to preventing kidney stones naturally and on kidney-friendly nutrition.
When to be careful
With heart failure, advanced kidney disease or a fluid restriction from your doctor, follow your doctor's advice – not the 2.5-liter rule.
Frequently asked questions
Does coffee count toward fluid intake? Yes. Coffee and tea add fluid and were linked to slightly fewer kidney stones in large studies.
Can you drink too much water? Yes, very large amounts in a short time can dangerously lower sodium. Spread over the day, 2.5–3 liters is fine for healthy people.
Does drinking a lot help pass a stone? It supports urine flow but does not replace medical treatment for colic.
Time-marked water bottles and water filters can be found in our recommendations below.
