I have been down this road and there is no way that I would have my cat on ANY dry food at all, with UTI problems. Mine has blocked twice, he ate only dry food at the time, it's been 5 years now, no blockages, and I put him on all wet food. Not to say that all wet food will solve the problem at this point, but dry food can probably aggravate it more. I have an immediate distrust of any vet that pushes dry food, even if it is special UTI formula stuff on a cat with urinary issues. I know I am on the right way of thinking too, my sister took her cat to an all cat vet yesterday and he chastised her for giving her cat any dry at all, said no, none. Because he has had issues. I believe that part of the problem is that it is habit now though, and he is continuing to pee places he has peed before, or he has associated pain from the UTI with the litter box. I swear by white vinegar and water and baking soda to remove cat pee smell.
I know how frustrated you are. I have been there. Just recently uncovered a pee problem myself, but it was one cat hassling the other which led to our problems. So I observed them after they ate in the morning and when I discovered the hassling, I kept little hassler in the den with the door closed until the other one with the issue had peed in the box peacefully, and I am continuing to do that every day, although it seems they are all back to normal...and I did add another litter box too. Most cats seem to go right after they eat in the morning, follow him and see where he goes, and see if you can catch him in the act, or sniffing around like he is going to pee, this is what I did. I have feliway spray, I spray a spritz of it every day in each room of my house that they go into. I think it helps too.
Try to hang in there, you will figure this out. I am not going to knock the perscription food, although I am not a fan of it, and if it works, great, the canned stuff anyway, but there is no way I would be giving my male cat dry food AT ALL if he was having these issues. Feeding Your Cat: Know the Basics of Feline Nutrition :: healthy cat diet, making cat food, litter box, cat food, cat nutrition, cat urinary tract health
my vet, 3 other vets I know and now my sisters vet that I do not know, all agree with the way of thinking of Lisa Pierson, the vet on this website. It is good information. More and more vets are coming around to this way of thinking instead of pushing their crap food on people.....and like I said, some of the people here have success with royal canin for urinary problems, so I am not going to say it is the worst thing, and at times it is necessary, but many of us opt for a food with better quality ingredients, especially for the price that it is, you could be feeding better quality ingredients. Not every one of us agree on that, but many of us who do agree on this way of thinking do so because we have been down this road and we know what worked for us. And yes, sometimes it doesn't solve the problem, especially if has been going on for a long time, but guess what......many times it does. It did in my cats case, which is why I am so passionate about telling people about it. And many relatives that I have known, and friends, I have seen their cats do a complete change around with a diet change. I have also seen a few on this forum who did not have such luck, so it is not always as simple as the diet change, but it can't hurt to try, and it could help.
Best of luck to you, so many of us have been down this road. I was just crying and having a nervous breakdown myself a few weeks ago about this very issue of peeing, I thought I'd lose my mind. I can relate.