Ask the vet -- struvite or oxalate? One thrives in high PH the other in low ... oxalate are genetic and harder to deal with.
It's *better* to get them to drink all the time -- you *can* put it in their food, but that slows digestion down. it's ok if it's the ONLY way to get water in them.
Try teaching him to like ice -- it can be great fun to crunch it up (particularly if it's flavored with a tiny bit of broth or yogurt. Not big ice cubes (can crack a tooth) but rather chipped ice if you can.
Often a big bowl of water gets stagnant .. so offering water -- to put it down more often may work.
For me and mine, I usually offer them ice out of MY drink. (and yeah, I'll get water, let the cubes 'soften' a bit JUST so I can get the dog to take the cubes from my drink if nothing more.
Now -- you can add either cranberry capsules or D-Mannose to the diet -- those are simply a form of glucose that helps bacteria be too slippery to adhere to the urinary tract walls -- You can do both (Don't bother with Solaray's Cran-actin+D-mannose - it's not the best proportion and it's unholy expensive). Now Brand Foods has a good D-Mannose and you can get it online in a bunch of places. D-mannose is kind of cranberry to the 3rd power, if you get my drift -- it's not cheap but it's cheaper than a zillion vet visits.