How to Kill Mold on a Sidewalk

Shoot down the sidewalk with a pressure washer to quickly clean the sidewalk and remove all mold growth. Sweep the washer's water jet from side to side and evenly cover the entire sidewalk surface, including areas that do not have visible mold growth.

Treat the sidewalk with a mold and fungus retardant to prevent the mold from growing back. Such products, which inhibit mold spores, can be obtained from a hardware store. Apply according to the product's guidelines, as chemical formulations vary by product.

Mix a homemade bleach killer if you do not have a pressure washer. Pour 4 cups of water and 1 cup of household bleach into a plastic bucket. Slosh the solution onto the mold growth. Allow the solution to sit on the mold for 30 minutes.

Scrub the bleached area with a broom or shop brush after the area has soaked in the solution. The bleach will kill the mold, but scrubbing is required to remove remaining mold stains and fibers. Scrub clean, then rinse thoroughly with a water hose.

Spray the mold with a mildewcide spray. This method is best for spot treatments on sidewalks that have limited amounts of mold growth. Spray onto the mold according to the product's guidelines. Most mildewcides do not need to be rinsed and will also retard future mold growth.