Reader Challenges "What's in Your Cat's Water."

Is Bottled Drinking Water Safe for Cats?

Close-Up Of Cat Drinking Water From Bowl
Chen Jie Huang / EyeEm / Getty Images


I have a problem with your article on What's in Your Cat's Water.

I just read your article on water for cats and agree with 99.999% of it. I disagree with the suggestion to use bottled water labeled "drinking" water.

Drinking water has minerals added,  alright: magnesium. The stuff that is carefully removed from cat foods these days to decrease the potential for FLUTD. A better option is Spring water if you don't have any urinary tract problems in the house, or distilled water if you do.


Thanks so much for your email. I took your comments directly to the FDA, which is the regulatory agency for both municipally sourced water and bottled water sold in the U.S. The EPA also sets standards for tap water, and the FDA draws on these standards in their regulations for "bottled water products that are in interstate commerce under the Federal Food, Drug, and Cosmetic Act (FD&C Act)."

You and I were both somewhat incorrect as to the addition of minerals to bottled water. The FDA regulations specifically prohibit the addition of anything to bottled water, with the exception of regulated amounts of fluoride. Although the bottled water company I referred to earlier in this reply did add small amounts of magnesium, according to its web site, it apparently no longer does. From a regulatory standpoint, the FDA describes bottled water as water that is intended for human consumption and that is sealed in bottles or other containers with no added ingredients, except that it may contain a safe and suitable antimicrobial agent.

Fluoride may also be added within the limits set by the FDA.

In addition to the FDA and the EPA regulations, the International Bottled Water Association (IBWA) has established a Model Code for bottled water, which in some ways is more stringent. And, of course, there are also state regulatory agencies.

In 2016, I re-verified the above information. It is essentially the same, as reported by IBWA:

The NRDC report confirms the results of the industry's own testing program. According to NRDC's independent testing, "most bottled water tested was of good quality. Most waters contained no detectable bacteria, and the levels of synthetic organic chemicals and inorganic chemicals of concern for which we (NRDC) tested were either below detection limits or well below all applicable standards." - See more at:

The FDA also classifies some bottled water according to its origin:

  • Artesian well water.
    Water from a well that taps an aquifer--layers of porous rock, sand and earth that contain water--which is under pressure from surrounding upper layers of rock or clay. When tapped, the pressure in the aquifer, commonly called artesian pressure, pushes the water above the level of the aquifer, sometimes to the surface. Other means may be used to help bring the water to the surface. According to the EPA, water from artesian aquifers often is more pure because the confining layers of rock and clay impede the movement of contamination. However, despite the claims of some bottlers, there is no guarantee that artesian waters are any cleaner than ground water from an unconfined aquifer, the EPA says.

  • Mineral water
    Water from an underground source that contains at least 250 parts per million total dissolved solids. Minerals and trace elements must come from the source of the underground water. They cannot be added later.
  • Spring water
    Derived from an underground formation from which water flows naturally to the earth's surface. Spring water must be collected only at the spring or through a borehole tapping the underground formation feeding the spring. If some external force is used to collect the water through a borehole, the water must have the same composition and quality as the water that naturally flows to the surface.
  • Well water
    Water from a hole bored or drilled into the ground, which taps into an aquifer.

Water Purification

According to the IBWA, "Purified Water - Water that has been produced by distillation, deionization, reverse osmosis or other suitable processes while meeting the definition of purified water in the United States Pharmacopoeia may be labeled as purified bottled water. . . Alternatively, '___ drinking water' can be used with the blank being filled in with one of the terms defined in this paragraph (e.g., 'purified drinking water' or 'distilled drinking water')."

The FDA Consumer Magazine offers brief descriptions of some of these purification processes:

  • Distillation
    In this process, water is turned into a vapor. Since minerals are too heavy to vaporize, they are left behind, and the vapors are condensed into water again.

  • Reverse osmosis
    Water is forced through membranes to remove minerals in the water.

  • Absolute 1-micron filtration
    Water flows through filters that remove particles larger than one micron in size, such as Cryptosporidium, a parasitic protozoan.

  • Ozonation
    Bottlers of all types of waters typically use ozone gas, an antimicrobial agent, to disinfect the water instead of chlorine, since chlorine can leave residual taste and odor to the water. Bottled water that has been treated by distillation, reverse osmosis, or other suitable process and that meets the definition of "purified water" in the U.S. Pharmacopeia can be labeled as "purified water."

Your closing remarks stated, "Even if you don't have any trouble with FLUTD now, adding 'drinking' water can cause it."

In light of what I've learned during this research, I find that to be unlikely since "drinking water" on a label would also include "purified" or "distilled" to comply with regulatory standards. However, I have no problem whatsoever with your suggestion of using spring water or distilled water for cats' water needs.