Interestingly, this is a question that is asked both by cat fountain owners and people thinking of buying their first cat fountain. People who don’t have a cat fountain want to know what the commitment is going to be, and people who have one want to know what they should be doing to ensure the health of their cats.
It’s a great question and an important one. But the answer to how often to change the water depends on several factors and the circumstances of each household. We, the owners of ThirstyCat Fountains. have one shorthair Orange Tabby who (sometimes) answers to the name of Bijou. He has an 11 cup capacity fountain and uses it a lot. We top it off about two times a week and clean the fountain and completely replace the water once a week. But had we another cat, the topping off and the cleaning and changing the water would be more often.
We have customers with two, or five and even eighteen cats. They, absolutely and very definitely, need to change the water in their cat fountains more often. Or, they need a number of cat fountains and can do them each much less frequently.
So, though there is no formula based on number of cats and volume of water that we are aware of, what we have found is that there are visible cues which are reliable. When the water level gets close to the top of the pump and you begin to hear the pump, top off the water level. If you start to hear the pump though there is plenty of water in the fountain, its time to clean the pump, and a good time to clean the bowl too. If you begin to see foam or white bubbles on the surface of the water, it’s about a day or two past the best time to clean the fountain and change the water. This is normally consistent so if you changed the water six days ago and you are seeing white foam or bubbles that don’t dissipate, changing the water every four or five days will be a reliable determination. The foam or white bubbles are from organic matter dissolved in the water – cat food, saliva, etc. Very likely you cat will continue to drink from the fountain with this but he would prefer not to. If we’ve gone a day or two too long before changing Bijou’s water, he will pause for just a moment before drinking, and will then drink but probably not quite as much. No doubt the water doesn’t smell and taste as fresh as he would like but is not, at this stage, harmful. So, though how often you need to change the water in your pet fountain is highly variable, you can know the signs and perform accordingly.
A similar question often asked is, which cat fountain is easiest to clean. Here is a post on that topic.