How much water does a small cat bowl carry?

I'm trying to figure out how many milliliters a small cat water dish carries. My cat is in the early stages of feline kidney disease and I want to get a good idea of how much water she is drinking in a day. I got several plastic food/water dishes at the dollar store. I placed several around the house. She has one favorite dish and I have to fill it up once or twice a day. She will sip water from the others but she likes the one we keep in the bedroom the most. I am estimating she is drinking 3 dishes of water everyday but I am not sure what the volume of those dishes are.