Hi again, and thanks for your additional information!
Blood in the urine is a signal that something is wrong in the kidneys or bladder, and the cause of that 'something' can have various reasons.
A urinary infection and/or the presence 'crystals', which are tiny particles that develop in urine which is not pH balanced (it's not acidic enough) can irritate the lining of the kidneys or bladder, thicken the bladder wall, and cause blood to appear in the urine. In male cats especially, because the urethra is so narrow, if crystals clump together and cause a blockage or obstruction, the cat will no longer be able to urinate, and this will become a medical emergency. His bloodstream will become poisoned by the toxins not being permitted to leave his body through the urine. If he's not showing signs of a blockage now, that's great, but you must bring him to the vet to be evaluated, have his urine tested, checked for infection and/or the presence of crystals, so then he can be treated accordingly. Antibiotics would be prescribed for an infection and dietary changes and/or nutritional supplements would be suggested to help acidify the urine to prevent a recurrence of crystals.
Also, encouraging him to drink more water would be great. You can get a cat drinking fountain, as cats love to drink from running water, and also very slightly salt his food.
I had asked if he eats non-food items, because if he has ingested something sharp or irritating, as it passed through his sytem, this could result in blood in the urine, also.
Another possibility is food allergies. Even if he's been eating the same food for a while, if it contains many 'fillers', especially corn, wheat, and/or gluten, in addition to any artificial colorings and preservatives, these are all common allergens to cats. A food allergy can cause irritation to the system, and again, blood in the urine.
Physical factors aren't the only reason a cat can have blood in the urine and/or a urinary infection; stress is another cause.
Felines are very sensitive and they are creatures of habit. What may seem like a very 'minor' change to we humans (like changing the configuration of your furniture), may have a huge impact on your cat's sensitive system. The cause may be emotional or psychological, but he result is physical, and can show up as an infection and blood in the urine.
To cut down on any stress your cat may be experiencing, you can use Feliway, a cat appeasing pheromone which comes in a spray and plug in diffuser form. The diffuser resembles a plug in air freshener, but has no scent to humans. It's sold in stores like Petsmart, etc., and also online. For more information about Feliway, please see: www.catfaeries.com/feliway.html
Clean the area he's already soiled with an enzymatic cleaner made for pet stains/odors. Some good products for this are Nature's Miracle and Zero Odor. There are many good cleaners for this purpose sold in Petsmart, etc., but make sure whatever you get, it says 'enzymatic'. When you clean with this type of product, no odor will remain, so your cat(s) won't think this is a 'correct' place to urinate.
Your cat has some of the classic symptoms of a urinary infection and/or crystals. For this reason, and because he's a male, this problem must be properly diagnosed and treated by your vet. There's no other course of action if you want him to get well and not worsen.
I wish you much good luck and hope that you will bring him to be checked out ASAP. Your vet is the only one who can put him on the road to wellness at this time, and prevent any major medical emergencies, like a urinary blockage. Please let me know how he's doing and what the vet's findings are. Thanks!