A few months back I wrote a column for the local neighborhood papers on using automatic food and water dispensers. I do not care for them for several reasons but one of the major issues I have with them is that they don't get cleaned often enough.
Most people who use these devices choose them for their convenience. It is easy to fill them up and let the dog or cat just help themselves to however much they want to eat or drink. (A problem in itself I think). But because of the ease of use, people either forget or ignore the fact that these dispensers need to be cleaned, and often; particularly the bowl part that the pet eats or drinks from.
Bacteria collects in there as well as dirt and it needs to be thoroughly cleaned with hot soapy water on a regular basis. Some of these dispensers are plastic while others are metal, stainless steel, ceramic etc. It doesn't matter what the material is, only that it is thoroughly cleaned on a regular basis.
Some dispensers I have come across while pet sitting are so filthy I can't imagine people allowing their pets to eat or drink from them. These are your "furry kids". You say you love them. Look at the bowls or dispensers you are serving their food and water from and if you wouldn't eat or drink from them, please don't make them.