---
title: "Why Is My Dog Drinking So Much Water UK?"
description: "UK guide to increased thirst in dogs — normal intake, common causes including diabetes and kidney disease, and when to book vet tests."
url: "https://pethealth.org.uk/health/why-is-my-dog-drinking-so-much-water-uk"
canonical: "https://pethealth.org.uk/health/why-is-my-dog-drinking-so-much-water-uk"
date_published: "2026-07-19"
date_modified: "2026-07-19"
source: "PETHEALTH+"
---

# Why Is My Dog Drinking So Much Water UK?

**Sustained excessive drinking usually signals illness** — commonly [diabetes](/glossary/diabetes-mellitus), kidney disease, or [Cushing's disease](/glossary/cushings-disease). Measure intake over 24 hours if unsure. Book vet **blood tests and urinalysis** if your dog's bowl empties faster than usual for more than a few days — do not dismiss it as normal ageing.

## How much is too much?

Average intake is about **50–60 ml per kg per day**, though this varies with diet, weather, and activity.

| Dog weight | Approximate normal daily intake |
|------------|--------------------------------|
| 5 kg (small) | 250–300 ml |
| 15 kg (medium) | 750–900 ml |
| 30 kg (large) | 1.5–1.8 litres |

Wet food provides much of daily fluid. Dogs on dry kibble only often drink more from the bowl — but a **sudden increase** still needs investigation.

## Common causes

- **Diabetes mellitus** — increased thirst and urination, sometimes weight loss despite good appetite
- **Kidney disease** — common in senior dogs; may start with subtle drinking changes
- **Cushing's disease** — excess cortisol; pot belly, thin skin, and increased thirst
- **Pyometra** — life-threatening womb infection in unspayed females; urgent vet care
- **Medications** — steroids and some diuretics increase thirst

## What to do

1. Note how much your dog drinks over 24 hours (measure the bowl)
2. Check for other changes — appetite, weight, urination accidents, lethargy
3. Book a vet appointment for blood and urine tests
4. Do not restrict water — dehydration worsens many conditions

## When to call your vet

Contact your vet **promptly** if excessive drinking persists beyond a few days or is paired with weight loss, appetite change, or lethargy.

**Same-day care** for unspayed females with drinking increase plus lethargy or vaginal discharge — possible [pyometra](/glossary/pyometra).

## FAQs

### Why is my dog drinking so much water?

Increased thirst (polydipsia) commonly indicates diabetes mellitus, kidney disease, Cushing's disease, pyometra in unspayed females, or certain medications. Less often, liver disease or infection is involved.

### How much water should a dog drink per day?

Most dogs drink roughly 50–60 ml per kg bodyweight daily — about 500–750 ml for a 10–15 kg dog. Drinking noticeably more than usual for several days warrants vet blood and urine tests.

### Can hot weather make my dog drink more?

Yes — dogs drink more in warm weather and after exercise. A temporary increase after a hot walk is normal. Sustained excessive drinking over days needs investigation.

### When is increased thirst an emergency?

Extreme lethargy, vomiting, collapse, or not eating alongside heavy drinking needs same-day care. Diabetic dogs can develop ketoacidosis — an emergency.

## Sources

- [PDSA — Excessive thirst in dogs](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub)
- [Blue Cross — Dog health](https://www.bluecross.org.uk/pet-advice)
- [MSD Veterinary Manual — Polydipsia](https://www.msdvetmanual.com)

Canonical HTML: https://pethealth.org.uk/health/why-is-my-dog-drinking-so-much-water-uk
Last modified: 2026-07-19