Yes, water is key! I forgot to mention I bought a cranberry supplement called Solid Gold Berry Balance to have on hand. I also bought some PH test strips. I test her urine PH every day (sometimes more than once). I ordered these things from Solid Gold. Since I have been adding can food and water to her food, and she took the round of antibiotics from the vet, she has maintained a PH of 6-7. I do feel, tho', that food can play a part. I think some foods are higher in phosphorus and magnesium and ash content and probably aren't the best to feed for dogs prone to urinary health issues. I'm sure raw or homecooked is best, but neither is right for me. Orijen is a fantastic food and I don't blame it for causing her UTI (I blame her lack of drinking while eating just dry food). I probably could feed it again and just add can/water to it, but I do have to order it online whereas I can get EPHS right at my back door. So, I have made my decision (for now). The other 2 eat the same thing. BTW, they do get fed twice a day and water is available at all times. I don't have the "not drinking as much" problem with the other 2. I do test the other dogs' PH's as well. So far all are maintaining right around 6-7. I think that is pretty good. Good luck to you in your search for a solution that might help your dog!
One more note: Here are some suggested foods for you. However some are lower in protein and fat than I like. I would definitely add can food/water to these.
Innova Senior (regular, not Senior Plus)
California Natural (Herring & Sweet Potatoe)
Flint River Ranch (Lamb, Trout)
Solid Gold Holistic Blendz
Eagle Pack Holistic Select
and I'm sure Wellness, Natural Balance and Merrick all have lower phosphorus/ash/magnesium foods as well (just contact their customer service reps.)