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Can Hard Water Cause Urinary Crystals in Cats? Vet Approved Facts & Advice

Written by: Kathryn Copeland

Last Updated on February 27, 2024 by Catster Editorial Team

filling a carafe with water

Can Hard Water Cause Urinary Crystals in Cats? Vet Approved Facts & Advice


Dr. Lauren Demos (DVM) Photo


Dr. Lauren Demos (DVM)


The information is current and up-to-date in accordance with the latest veterinarian research.

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Keeping your pet safe and in good health is an essential part of taking care of a cat. Unfortunately, there are times when your pet might become ill regardless of your best efforts.

The chance of your cat dealing with conditions like urinary crystals typically depends on factors like their age, breed, and diet, but can hard water cause crystals in the bladder?

One 2016 data release did discover a potential association between hard water and urinary crystals in cats1. However, there is no targeted, scientific data to back up these claims.

Here’s information about hard water and urinary crystals and whether you should be worried about your cat’s bladder.

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The Study

On April 7, 2016, pet insurance company Trupanion released a report that examined the link between hard water and urinary crystals in pets2. It used data from the Environmental Protection Agency that enabled the researchers to compare U.S. cities with hard water to the claims put through Trupanion for pets with urinary problems.

cat drinking from faucet
Image By: Sample Stars, Shutterstock


It was found that studied cats were 40% more likely to experience urinary problems than studied dogs. Additionally, male cats were 1.5 times more likely to encounter urinary problems than female cats.

The highest claimed urinary conditions among cats were:

  • Urinary tract infections
  • Cystitis
  • Urinary obstruction
  • Crystalluria

Hard Water

It was also discovered that U.S. cities with “extremely hard water” had a much higher rate of urinary health claims, with an emphasis on crystalluria, which are the crystals found in cat’s urine3. The male cats in these cities were found more likely to have urinary conditions than those in cities with “slightly hard,” “hard,” or “very hard” water.

Trupanion used the example of Florida, which it classified as having “extremely hard water.” It encountered 10 times the number of claims in Florida than in the other states. The other cities listed as having “extremely hard water” were Chicago, Detroit, Cincinnati, Miami, and Minneapolis.

However, the statistics and information from this report are now over 7 years old. If you want to determine if you live in an area with hard water, check your region’s water-quality report.


What Exactly Are Urinary Crystals?

Urine contains solid waste particles, which turn into more solid particles like crystals when the concentration of waste products is high enough. These crystals get bigger and may eventually become stones, which may continue to increase in size if not treated.

Bladder stones can lead to urinary tract infections or a urinary tract blockage, which needs immediate medical intervention!


It’s not entirely known what typically causes urine crystals, but the following are considered the potential contributing factors:

  • Breed
  • Sex
  • Age
  • Diet
  • Certain health conditions


The common signs for cats with urine crystals and bladder stones are:

  • Straining to urinate
  • Increased urination
  • Only urinating tiny amounts of urine
  • Urinating outside of the litter box
  • Blood in the urine


Female cats can sometimes pass very small stones on their own or with flushing, but male cats tend to have more trouble passing them.

Some stone types can dissolve through a prescription diet, but if they are too large, they need to be removed via surgery. If a blockage occurs, this is a life-threatening emergency that will often require a cat to be hospitalized for a few days.

tabby cat sitting in a litter box
Image Credit: Lightspruch, Shutterstock

What Makes Water Hard?

The main culprits that can cause hard water are calcium and magnesium. While these minerals benefit our health overall, excess dissolved magnesium and calcium can damage equipment (like dishwashers) and dry out skin and hair.

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What If You Have Hard Water?

It isn’t an absolute certainty that if your cat drinks hard water, they are automatically vulnerable to urinary crystals. There haven’t been any peer-reviewed studies on the matter.

That said, the statistics that Trupanion gathered might still be something to take into consideration when you’re supplying your cat with water, particularly if you have a male cat, since males are more susceptible to urinary crystals.

1. Water Softener

You can invest in a water softener for your home or a small ion-exchange water filter that can be attached to your tap. This is the best way to remove the excess minerals that lead to hard water.

2. Boiling the Water

boiling water using a ceramic tea pot
Image By: Ioann-Mark Kuznietsov, Unsplash

A more complicated route is boiling the water that you need.  It needs to be boiled for several minutes, cooled, and then poured through a sieve or cheesecloth to remove the minerals boiled out. It is not as effective as other methods.

3. Water Filters

Unfortunately, most water filters don’t remove as many of the excess minerals as water softeners do. These include cat fountains with charcoal filters.

However, water filters can remove some of the excess impurities from tap water and are still good options, particularly if you can’t afford a water softener.

4. Bottled Water

cat resting near bottled water
Image By: MVolodymyr, Shutterstock

Bottled water is considered soft water because it contains low levels of magnesium and calcium, which makes it a viable option for your cat.

Just don’t bother with distilled water, as there haven’t been any studies that say that it’s safe to give distilled water to your cat as their only water source. It won’t harm your cat, but since it doesn’t contain any minerals, it isn’t necessarily beneficial either.

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Although the data for cats at present remains lacking, if you live in an area that has been classified as having “extremely hard water,” it might be in your best interests to invest in a water softener. The water might not affect your or your cat’s health, but it will undoubtedly damage some of your major appliances.

Overall, there don’t seem to be any serious human health risks associated with drinking hard water, including urinary crystals, but more studies need to be done on the effects of hard water on cats.

Featured Image Credit: Sanchit Singh, Unsplash

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