How to Locate Pet Urine Stains With a Black Light

It happens to most dog and cat owners: a stench comes from somewhere within the house, yet you can't locate the source of the urine smell.

If the urine stain is old, it's very difficult to find how large it may be, especially if the urine seeped through carpet and infested the carpeting. By using a black light, urine spots that remain unnoticed to the naked eye can be found.

Use your nose to locate sources of urine odor. Although fresh urine stains should be easier to find due to their smell and wetness, you still need a black light to find older stains.

Turn off all lights. It's best to use your black light when the room is as dark as possible. Shine the black light on the area where you think there are pet urine stains.

Locate the urine stains. Due to the black light, the stains should resemble a green glow. Once you find areas that are stained, use chalk to outline those areas. This can help you locate the stain with the lights on in order to clean it. You could also clean the areas as you go.

Try an enzyme-based cleaner to rid your stained area of the animal urine. It's best to use these types of cleaners, as they remove any trace of the urine, preventing your animal from peeing in the same spot.


  • Cats are rather sly animals and can maneuver into the smallest of spaces. Take your time and be thorough when checking your house.
  • Locating the source of the animal urine smell is vital, and the earlier it's found, the better. You can decrease damage to your floors, walls, furniture and clothing.