I never had any success with Nature's Miracle. When I lived in the aprtment, Mr. Amber Cat routinely peed out of the box. UGH!

When I bought my house, I made sure: NO carpetting, all hardwoods and linoleum. For easier clean ups. The new hardwoods which I had put in stand up well; the old ones stain. Will need to have those refinished eventually.

Prevention is the only clear way out, that I know of. I've had 15 cats in 14 years. Prevention means plenty of litter boxes, and knowing who has a UTI as soon as possible!

I know you said you aren't going to add boxes but, consider your options: more boxes or hunting around for stains and trying to remove odor. Oh, they sell black lights which you can use to find the stains. I even bought one of those, but knowing where the stain was didn't help eliminate it.

Some cats won't use a box that has been used. Some won't use a box that a certain OTHER cat has used. Some want one for pee and another for poop. Some guard the box and won't let anyone else use it.

Maybe others have had success removing the odor, but I never did. Best wishes! Sandie