go get a larger drinking fountain for both. Moving water encourages drinking which cats usually don’t do enough. Most have filters to keep the flowing water clean, again a good thing. More pissing, less kidney troubles.
Most have filters until your cat learns how to get at them. My son's little female cat figured out how to get the top off the section where the filter is. She'd take the filter out, then proceed to destroy it. She hasn't done it in a while, so perhaps she's outgrown it. On a different style of fountain he previously had, she'd stick her paw up into the hole where the water was flowing from, and pull the filter out. One of my cats used to pull the filter out of the fountain I had here too. Once the novelty of it wore off, he stopped.