NatureMade Cranberry Extract capsules have always kept me clear. I've been taking them since before I got pregnant and now I'm 37 weeks and never had a UTI in my whole pregnancy. It also has Vitamin C which is good for baby too. Just take it twice a day with food. And yes do drink LOTS of water!
I have had 3 urinary tract infections so far and I decided that I no longer wanted to take pills during pregnancy so.. Cranberry juice (because it's acidity keeps bacteria from sticking to urniary tract), water, shower more often to reduce risk of bacteria traveling into her urinary tract, change underwear often for same reason as showering, and ALWAYS wipe front to back. Keep up that routine and she should be good. also, try not to use soap when showering directly on the urethra.