If your cat is drinking noticeably more than usual for more than 2 days, schedule a vet appointment. Increased thirst combined with weight loss, lethargy, or vomiting warrants a same-day call.
What Counts as “Too Much” Water?
A healthy cat drinks 3.5–4.5 oz of water per 10 lbs of body weight per day. A 10-lb cat drinking more than 8 oz daily consistently may have polydipsia — medically significant increased thirst.
Wet food-fed cats drink less because they get moisture from food. If you’ve recently switched to dry food, increased drinking is expected and normal.
The 5 Most Common Causes
1. Chronic Kidney Disease (CKD)
The most common cause in cats over 7. Damaged kidneys can’t concentrate urine, so the body compensates by drinking more. CKD affects 30–40% of cats over 10 years old.
What you’ll see: Increased thirst, weight loss, reduced appetite, occasional vomiting.
2. Diabetes Mellitus
High blood glucose pulls water out of tissues. Diabetic cats drink and urinate excessively — often the first signs owners notice.
What you’ll see: Large clumps in the litter box, weight loss despite good appetite, lethargy.
3. Hyperthyroidism
An overactive thyroid gland speeds up metabolism, including kidney filtration. Very common in cats over 10.
What you’ll see: Weight loss with increased appetite, hyperactivity, vomiting, unkempt coat.
4. Urinary Tract Infection (UTI)
Less common in cats than dogs, but UTIs cause irritation that increases the urge to drink. More common in female cats.
What you’ll see: Frequent small urination attempts, straining, blood in urine.
5. Liver Disease
The liver regulates many metabolic processes. When compromised, it can trigger increased thirst as a secondary effect.
What you’ll see: Yellowing of gums/eyes (jaundice), vomiting, decreased appetite.
If your cat is straining to urinate and producing nothing, go to an emergency vet immediately. A urinary blockage (more common in male cats) is fatal within 24–48 hours without treatment.
What the Vet Will Do
A diagnostic workup for polydipsia typically includes:
- Blood panel — checks kidney values (BUN, creatinine), thyroid, blood glucose, liver enzymes
- Urinalysis — measures urine concentration, checks for infection
- Blood pressure measurement — hypertension is common with CKD and hyperthyroidism
Cost: $150–$350 for a full diagnostic workup at a general practice.
Frequently Asked Questions
Can stress cause increased thirst in cats?
Rarely. Stress can affect appetite and behavior, but significant polydipsia is almost always medical, not behavioral.
Should I restrict my cat’s water intake?
Never. If your cat is drinking more, let them. Restricting water while a medical condition is driving increased thirst can cause dehydration and accelerate organ damage.
My cat eats wet food and is still drinking more. Is that worse?
Yes — a wet-food cat that’s drinking noticeably more is a stronger signal because they’re already getting significant moisture from food. Prioritize a vet visit.