I thought I'd blog about this as it's a simple and easy trick, which might make life easier for many cats (and their staff)..
If your cat doesn't seem to drink enough water, or if s/he seems to have a problem drinking it, you should try giving them warm water.
Note: do not get warm water straight from the tap (just in case). Instead, fill the water bowl with maybe 3/4 or 4/5 cold water, add some boiled hot water, and mix it with your finger.
The reason I'm suggesting you mix it with your finger, is that it's an easy way of telling when the water temperature is good. Ideally, when you mix the water, it should be almost as if you can't feel it at all - that's when it's exactly your body temperature. It can be a little bit warmer, too, because cats actually have slightly higher body temperature than people (38.6C / 101.5F).
This has really made a huge difference with Oimo, and with Ginga as well! Oimo wasn't great with drinking, and he'd often "eat" the water, rather than drink it normally with his tongue, as cats are supposed to do. He didn't seem to get enough water, and it got worse when he lost a fang.
When he got warm water, he immediately started drinking normally, and he would drink lots of it! He now gets warm water several times a day. (Obviously, it won't stay warm for long, but I always make him warm water when I feed him, and if he gets thirsty between meals, he knows to come and ask for it..)
Ginga is an outdoor cat (semi-feral), and although I've offered him water many times, over the years, he's never been interested at all. So, I thought he must have had his own drinking spots somewhere, and just continued feeding him with wet food. However, now that he's getting old and blind, I sometimes let him eat in the kitchen at night, and he has actually drank some warm water as well!
This is definitely worth trying, if your cat has a drinking problem!