I change it several times a day. I have multiple cats and notice they all prefer fresh, clean water. I can't say I blame them, as so do I. ;-)

I bought one of the filtered pet fountain thingies...thinking, 'this will be great!'. It turned out to be REALLY inconvenient to clean. The slime build up would attach to anything that came into contact with the water and cat hair clogs the aerator/filter. Plus, the cost of replacement filters made the whole thing not worth it.

I went back to a regular glass bowl. I change it several times a day. My diabetic kitty will ONLY drink out of it if it's clean and has very, very cold water. Plus, he is always dropping food particles in it and shares it with my other kitties who do the same thing.

I hate automatic waterers, they attract carpet hair, dirt and are a pain to clean out. It is so much easier to just pick the bowl up a couple of times a day. Who wants water that has been sitting out for days....bleck

I recently resurrected the kitty water fountain from the basement. I don't think I'm going to bother to buy a filter for it. I'm not using the water reservoir tank either. I've been using an old turkey baster to suck out the cruddy water (I also shoot some in by the little pump so the collected hair & bits of food or whatever come out). Then I refill the bowl with filtered water from the fridge dispenser. Seems I have to add a little fresh water daily and suck out the crud every couple days or so.

The cats also have the option of drinking from the dog water bowl but I have the fountain up higher so the dogs can't get to it.

I personally love kitty water fountains. I have two, like the one pictured, that sit away from the cat food - I never have food stuck in them. I refill them every 3 to 4 days.
I also have a big ceramic bowl for water, for those who prefer to drink from the bowl, instead. I refill it daily or every second day.

One of my kitties suffers from crystals so it is very important for him to drink a lot of water. I have an electric fountain, gravity bowl and regular water bowls. I change the bowls daily and the fountain when I see food, hair or grime. Each kitty has an individual preference and as long as they are drinking water I don't mind giving them several options.

We change our cats' water and wash out the bowl every morning. We give them water from the dispenser on our fridge (which is double-filtered; one filter is on the water line going to the fridge, the other is the refrigerator filter itself). "If it's good for us, it's good for our cats..."

We also add warm/hot water to their wet food when we feed them, to add add'l water to their daily intake. One of our cats seems to prefer the soupiness anyway, so it's a win-win.

I had one of those old fashioned auto-watering (gravity) devices when I had a house full of cats. I changed the water frequently BUT.........the water chamber was built with a narrow neck, and looked like the water cooler jugs humans use.

I noticed down the line that the bottle was taking on a blue appearance and worked and worked with a bottle brush trying to clean it and discovered it was algae. That is BAD, BAD, BAD. That type of 'blue/green water' algae poisons the water. So, I pitched it and went to a bowl.

I think not only changing the water frequently is necessary, sanitising the bowl frequently is also.

I find that one of my cats absolutely will not drink out of the water bowl if our lab did so. Because of this, I have to change the cats drinking water several times a day. For whatever reason, however they will all drink out of the heated waterer outside even though many varieties of animals drink out of it (including deer.)

When my one cat was young, he drank out of the toilet. He liked it clean and cold. My other cat drank out of a bowl on the floor that had to be cleaned frequently because she liked to stick her feet in the water!! Yuck. She has passed now, and the other cat likes the bowl. He and the dog get clean water at least once a day - provided I remember :)

I had a bubbling cat fountain but it was hard to clean and the filters were expensive. I was also concerned about germy growth in it over the long term. There had to be a better way. So, I got a fairly deep ceramic dog bowl, a cheap aquarium pump, tubing and an airstone-the thing that makes bubbles. You can put the pump anywhere and snake the tubing as long as you need it to get to the bowl. The airstone creates soft bubbles that my cat loves. I change the water every day or so, then every few days dump it in the sink and put the bowl in the dishwasher. No muss, no fuss, happy cat. (I didn't tell her it was a dog bowl :-)

Oregpsnow: can you post a pic? that sounds quite clever!

Twice a day, unless something gets in it, in which case I change it again.

If case oregpsnow doesn't have a pictures handy, you can easily find pictures and directions for homemade cat fountains if you google "DIY cat water fountain" or something similar. A couple of examples:

{{!gwi}}

I am thinking of going this route, too, as my fountain is a pain to keep clean!

Paco will only drink water from a glass, preferably MY glass next to me wherever I happen to be sitting. So, I now carry two glasses to the sink for a refill, one for him and one for me. (He still tries to drink out of mine, first.)

He'll look at me balefully if he thinks the water is not fresh enough, then sit and wait patiently until I get up and tend to his bidding.

I tell him that I'm not gonna take his crap any longer, but we both know that that would be a bald-faced lie.

I don't keep the water near the catfood so I don't get kibble in it. I have a gravity fountin both the cats and dogs use it. The cats still go on the quest for water. Oreo drinks out of the toilet if the seat is left up. She also drinks out of the bathtub tap if there is the smallest drip. RocKat wants a fresh glass of water, the one I am drinking out of is best. He likes wine glasses best. Kreem drinks out of the horse water tub, he can stand on the rim and drink. He forces me to keep the bucket up because if he falls in he will drown. We have a 1/2 acre pond they all go there and drink. They like rain water on the firewood tarp too.

I have 5 cats. None of them liked the fountain I bought from Foster/Smith, so I returned it. They all seem to be satisfied with fresh water once a day (several dishes). Then again, even though they have access to the fresh water inside and all drink that, I also often find them drinking the most godforsaken dirty water outside, collected in a tree, or whatever rainwater receptacle that's laying around, so who knows? Maybe the tap water is too "processed" for them. I have great well water in my city, but I use a filter bc it tastes bleachy to me.