Can Drinking Water Prevent Kidney Stones? What the Guidelines Say

If you have had a kidney stone, you want to know how to stop another one. The simplest and best-supported step is also the easiest to start today: drink enough water, spread through the day.

This guide explains what the current medical guidelines say about water, what else lowers your risk, and when a stone needs a doctor right away. It is general information, not medical advice, and it cannot dissolve or treat a stone you already have.

Quick answer: doctors aim for enough fluid to make about 2.5 litres (85 ounces) of urine a day if you have had calcium stones. Pale, light-coloured urine is a good sign you are on track.

Why does water help prevent kidney stones?

Stones form when urine contains high levels of substances like calcium, oxalate and phosphorus that can clump together. More water makes your urine more dilute, so those substances are less likely to stick together and form crystals.

The strongest evidence comes from a five-year randomized trial in people who had a first calcium kidney stone. Those told to drink more water, enough to make about 2 litres of urine a day, had far fewer new stones than those who did not: about 12% had a recurrence versus 27% (Borghi et al., 1996).

How much water should you drink?

The American Urological Association's updated guideline, published in July 2026, says adults with calcium-based stones should drink enough water to produce at least 2.5 litres of urine a day (AUA guideline summary). That is about 85 ounces of urine. For children it suggests at least 30 mL per kilogram of body weight.

Notice that the target is urine, not the amount you drink. Because you also lose water through sweat and breath, you usually need to drink more than 2.5 litres to reach it. The NIDDK's general advice for people with stones is to drink mostly water, around six to eight 8-ounce glasses a day, unless you have kidney failure (NIDDK). Your own number depends on your size, climate and activity, so ask your doctor what is right for you.

• Spread it out. Sip through the day instead of drinking a lot at once.
• Drink more when it is hot or when you exercise, because sweat lowers your urine volume.
• Check your urine. Pale yellow means you are doing well. Dark yellow means drink more.
• Drink a glass before bed if your doctor agrees, since urine is more concentrated overnight.

If you also want a general daily target, see how much water you should drink a day in ounces or in litres.

What else lowers your risk?

Water comes first, but food choices also matter. The right plan depends on the type of stone you had, so confirm the details with your doctor or a dietitian.

• Limit sodium. The NIDDK advises adults who have had calcium stones to keep sodium under 2,300 mg a day. One teaspoon of table salt has about 2,325 mg, and most of it comes from packaged, canned and fast food (NIDDK).
• Keep calcium in your diet. Calcium from food does not cause calcium stones. It binds oxalate in your gut so less reaches your kidneys, so do not cut dairy or other calcium-rich foods on your own.
• Watch animal protein. Depending on your stone type, your clinician may ask you to limit beef, chicken, pork, eggs, fish and dairy. Beans, lentils and dried peas are options.
• Limit high-oxalate foods if you form calcium oxalate stones. The NIDDK lists nuts, peanuts, rhubarb, spinach and wheat bran.
• Keep a healthy weight and eat a balanced diet such as the DASH eating plan.

What are the symptoms of a kidney stone?

Common signs include sharp pain in the back, side, lower belly or groin that can come in waves, pink, red or brown urine, a constant need to urinate, pain when urinating, and cloudy or bad-smelling urine. Nausea, vomiting, fever and chills can also happen (NIDDK).

When should you see a doctor?

See a health care professional right away if you have any of these symptoms. Get urgent or emergency care if you have:

• Severe pain that you cannot get comfortable with.
• Fever or chills along with the pain, which can mean an infection.
• Vomiting that does not stop, or you cannot keep fluids down.
• Little or no urine, or you cannot pass urine at all.

Do not try to flush out a painful stone by forcing large amounts of water. Get it checked first. A doctor may recommend tests, pain relief or treatment, and a stone analysis to guide how to prevent the next one.

How to make drinking enough water a habit

Knowing your target is easy. Hitting it every day is harder, especially in a busy week. A water tracker helps because you can see how much you have had at a glance.

• Set your own daily goal to the amount your doctor gives you.
• Log a glass in a tap, on your iPhone or Apple Watch.
• Get gentle reminders through the day, which stop once you have reached your goal.
• See your history to spot the days you fell short, with optional Apple Health sync.

Download Hydrabit on the App Store. It is free to use, has no account, and keeps your data on your device. Hydrabit is a tracking tool and does not provide medical advice.

Frequently Asked Questions

The bottom line

Water is the simplest way to lower your chance of another kidney stone. Aim for a large amount of pale urine each day, cut back on salt, keep calcium in your food, and see a doctor for pain, fever or trouble passing urine.

Pick your daily goal, log your glasses and let reminders do the work. Download Hydrabit to track it.

Sources

• American Urological Association: Medical Management of Kidney Stones guideline, July 2026 (summary)
• NIDDK: Eating, Diet, & Nutrition for Kidney Stones
• NIDDK: Symptoms & Causes of Kidney Stones
• Borghi et al.: Urinary volume, water and recurrences in idiopathic calcium nephrolithiasis, a 5-year randomized prospective study (1996)