Cat Drinking a Lot of Water But Acting Normal? When to Worry

The general rule of thumb is that a cat needs approximately 4 ounces (about ½ cup) of water per 5 pounds of lean body weight per day.

• For a 10 pound cat This equals roughly 1 cup of water daily.
• For a 15 pound cat This equals roughly 1.5 cups daily.

However, this intake doesn’t always come purely from the water bowl.

• Diet matters Wet food is approximately 80% water. If your cat eats exclusively wet food, you may rarely see them drink from a bowl. Conversely, cats on a dry kibble diet (which is only 10% water) will naturally visit the water bowl much more frequently to compensate.

• The Litter Box Test What goes in must come out. Increased drinking almost always leads to increased urination (polyuria). Look for significantly larger urine clumps in the litter box or a box that is wetter than usual.
• Unusual Drinking Locations Is your cat suddenly drinking from the toilet, the shower floor, or begging at the kitchen sink?
• Frequency The average cat might visit the bowl 5–6 times a day. If your cat is hovering over the bowl constantly, take note.
• Empty Bowls If you are refilling the water bowl significantly more often than you used to, your cat’s intake has likely spiked.
• Pro Tip If you are unsure, measure it. Fill the bowl with a measuring cup in the morning (e.g., exactly 2 cups) and measure what is left 24 hours later. Do this for a few days to get an average.

• Dietary Switches Did you recently switch from canned food to dry kibble? If so, your cat suddenly drinking a lot of water is likely a normal physiological response to the lower moisture content in their food.
• Heat and Activity Just like humans, cats get thirsty when it’s hot or after intense play sessions. Central heating in the winter can also dry out the air, leading to increased thirst.
• Medication Side Effects Are you treating your cat for another condition? Common medications, including diuretics (water pills) for heart issues, steroids (like prednisone), and certain anti-seizure drugs, are known to stimulate thirst.

• 1 Kidney Disease Chronic Kidney Disease CKD
  This is the most common cause of an older cat drinking a lot of water. As cats age, their kidney function can deteriorate. When the kidneys lose the ability to concentrate urine efficiently, the cat loses excess fluid through urination. To prevent dehydration, the cat compensates by drinking massive amounts of water.
• 2 Diabetes Mellitus
  Diabetes is frequently seen in overweight or middle-aged male cats. In diabetic cats, excess blood sugar spills over into the urine, pulling fluid with it. This leads to a cycle of frequent urination and extreme thirst.
  Watch for Weight loss despite a ravenous appetite, and sticky urine.
• 3 Hyperthyroidism
  Caused by an overactive thyroid gland, this condition speeds up the cat’s metabolism.
  Watch for A cat drinking a lot of water, rapid weight loss, hyperactivity, and increased vocalization (yowling at night).
• 4 Urinary Tract Issues
  While a lower Urinary Tract Infection (UTI) usually results in straining to urinate, a kidney infection (pyelonephritis) can cause increased thirst.
  Watch for Frequent attempts to use the litter box, small amounts of urine, or blood in the urine.

Do not ignore this.

Cats are masters of disguise. By evolution, they are hardwired to hide pain and illness to avoid becoming prey. The early stages of kidney disease and diabetes often present only as increased thirst and urination. By the time the cat starts “acting sick” (vomiting, lethargy, hiding), the disease may have advanced significantly. Increased drinking is the early warning sign.

• The History The vet will ask about diet changes, litter box habits, and behavior.
• The Diagnostics
  • Urinalysis Checks how well the kidneys are concentrating urine and looks for glucose (sugar) or bacteria.
  • Blood Work CBC Chemistry Checks kidney values (creatinine/BUN), liver enzymes, blood sugar, and thyroid levels.
• The Treatment
  • Dehydration If your cat is dehydrated, they may need immediate fluid therapy.
  • Management Most conditions are manageable. Diabetes may require insulin and diet changes; Hyperthyroidism can be treated with medication or radioiodine therapy; Kidney disease is often managed with specialized diets and hydration support.

• Q Do cats drink more water when they are sick?
  A Yes. Because cats are prone to kidney and urinary issues, increased thirst is one of the most reliable indicators that something is physically wrong.
• Q What are the red flags that indicate an emergency?
  A You should seek immediate emergency care if the thirst is accompanied by vomiting, diarrhea, sudden collapse, or—most critically—if a male cat is straining to urinate but producing nothing. This could indicate a life-threatening urethral blockage.
• Q Can I treat excessive thirst at home?
  A Never withhold water. Limiting water intake for a thirsty cat can lead to dangerous dehydration and organ failure. You cannot treat the thirst itself; you must see a vet to treat the underlying cause.
• Q My cat is drinking a lot of water; is it just the hot weather?
  A If it is summer, it might be. However, if the weather cools down and the drinking continues, or if the increase is sudden and dramatic, do not assume it is just the temperature.

Disclaimer: This article is for informational purposes only and does not constitute veterinary advice. Always consult your veterinarian if you are concerned about your pet’s health.