Summarize:

As your cat ages, they will have an increasing level of susceptibility to UTI infection. This is due to changes in your cat's urinary tract and liver function. Young cats under 7 years of age have a low risk of urinary infections. This is because they are excellent at concentrating their urine, and strong urine is a natural disinfectant that inhibits bacterial growth. If you see signs of blood in a young cat's urine, it is likely that he has a problem not caused by infection, but by crystals, stones, or inflammation from an unknown source that has irritated the bladder lining. There is a distinct risk that crystals will clump together and form a blockage in the urethra the tube the cat urinates out of. If this happens, it is an emergency that needs immediate veterinary attention. Older cats over 7 years of age are at an increased risk of infection. Older cats have a reduced ability to concentrate urine, and as the cat ages he is quite likely to produce dilute urine because of a reduction in kidney function. This weak urine is not a very potent disinfectant and urinary infections become more likely. Again, it is important to treat these infections before they ascend into the kidney and cause significant damage leading to scar tissue formation. Although dilute urine is risk factor for UTI, once your cat has a UTI, regular, steady urination will help him flush his bladder out. Bacteria produce waste products and chemicals that can irritate the bladder lining, causing inflammation. Regular hydration can dilute these factors and limit the amount of time they spend in contact with the bladder wall, helping reduce inflammation and soreness. To increase your cat's water intake, switch him form a dry to a wet food. This automatically increases the amount of fluid he takes in. Also, provide plenty of wide drinking bowls. Cats seem to prefer drinking from wide containers where their whiskers don't touch the side. Some cats will drink more if provided with flowing water such as that from a cat drinking fountain. Other cats dislike the chlorine and chemicals in tap water and are much happier when offered bottled water to drink. Some veterinarians recommend cranberry capsules to reduce the risk of a UTI. The cranberry extract contain proanthocyanidins, which may make it more difficult for bacteria to adhere to the bladder wall. Consult your vet before starting any supplement in your cat. Your vet will approve the supplement and instruct you on an appropriate dose. Do not be tempted to increase the amounts of these supplements, because there is a risk of reducing the urinary pH too much and the extreme acidity could irritate the bladder lining.
Understand age's effect on UTI risk. Encourage your cat to drink to flush his bladder. Feed your cat cranberry capsules or ascorbic acid to acidify urine.