Cat urine on a lawn, vegetation or houseplants leaves a strong smell. The urine can also kill plants, causing brown spots on a lawn where an intact male cat has sprayed or spots on leaves of houseplants, where a cat has dug in the soil to urinate.
Cat urine has a high concentration of nitrogen, which occurs when proteins are broken down in the body. The urine carries the excess nitrogen from the body via the kidneys. This excess nitrogen may cause damage or even kill plants.
Pouring water on the urinated areas may help dilute the urine. This is only helpful if you spray the area within the first eight hours. After 12 hours, pouring water on the urine actually forces it into the soil and may make the problem worse.
Use sprays that keep cats from urinating in a particular location. The sprays have a strong smell that keeps the cats away, without damaging the vegetation. For houseplants, you could try placing a wire screen in the diameter of your pot with a slit to fit around the plant. Top the screen with pebbles or gravel to deter digging and urinating in the pot.