Is Boric Acid Mixture Down the Kitchen Drain Safe?

Boric acid is a product of boron, a chemical element that is a combination of metal and nonmetal substances, used as an insecticide and an antiseptic. The acid is considered weak and is often part of a solution containing water or another liquid. It is safe to pour a boric acid mixture down your kitchen or other drain in your home or business.

Boric acid dissolves quickly in running water.


Boric acid dissolves in water and is not harmful to the environment, storm drains, septic systems or other waterways. The acid exists in the form of a white powder or as colorless crystals. But like other chemicals and substances, you should not swallow or drink boric acid no matter what form it is in. The acid will make you sick and possible kill you — especially children and pets.

Medical Uses

Boric acid has antibiotic properties — it helps fight bacterial and fungal infections in humans and animals. The substance is found in eyewashes, creams and sprays. Eyewash containing boric acid is known as boric acid ophthalmic. The liquid cleanses and removes pollutants including smoke, chlorine and other chemicals from your eyes. When using the eyewash, stand over a sink and let any excess solution flow down the drain. Boric eyewashes are also available that irrigate your eyes.

Household Uses

The acid is an ingredient in all-purpose household cleaners, including homemade and commercial products. Boric acid is also found in drain cleaners. The chemical safely breaks up clogs and debris in both septic and nonseptic drain systems. To make a nontoxic cleaner using the acid, mix 1 qt. of hot or warm water, 1 tsp. of liquid soap, 1 tsp. of boric acid and 1 tsp. of lemon juice in a bucket. Stir the mixture and transfer it into a spray bottle. The lemon juice gives the cleaner a fresh smell and the boric acid helps break up grease and dirt.


Boric acid is also used as an insecticide and is in commercial insecticides. The acid kills a variety of bugs, including roaches, ants, silverfish and other insects. Simply sprinkle boric acid around areas of your home where you have seen insects. The bugs eat the acid and die. Use caution when sprinkling the acid around pets — boric acid is deadly to animals. Also, keep the acid away from children.

Nick Davis

Nick Davis is a freelance writer specializing in technical, travel and entertainment articles. He holds a bachelor's degree in journalism from the University of Memphis and an associate degree in computer information systems from the State Technical Institute at Memphis. His work has appeared in "Elite Memphis" and "The Daily Helmsman" in Memphis, Tenn. He is currently living in Albuquerque, N.M.