How often do you thoroughly clean your drinkwell water fountain for your pets?

I clean mine out really well once in a while, but I worry that it may have a soap taste if I do not rinse it well enough and the cat's won't drink from it. I also worry about bacteria growing in the parts that I can't clean like the pump..... Do you think that is a problem?How often do you thoroughly clean your drinkwell water fountain for your pets?probably 3 days after u did it