Whether you live in a damp climate or your walkway is always in the shade, you're bound to find mold or mildew growing on concrete.
It can be quite frustrating to hose it off and watch it come right back. Scrubbing it off with a push broom doesn't take care of the problem either.
You have two effective options for removing mold and mildew from concrete.
1. Scrubbing With Bleach
Combine 1/4 cup of liquid bleach with 1 gallon of hot water in a large bucket. Using non-diluted bleach may work, but mixing it with water is more conservative and less likely to cause damage to your sidewalk.
Before you begin cleaning, put on rubber gloves. Soak your brush in the solution and scrub the entire area until it's fully saturated. Let it soak before cleaning it up.
Never put bleach in your pressure washer, as it'll ruin it.
2. Pressure Washing With Detergent
To make things safer and easier, use a mold and mildew house and siding detergent that is safe for your pressure washer!
If you choose to go this route, you can simply fill your detergent tank and begin spraying your siding with soap. Let it soak, and you'll be ready to blast away the grime.
Once the solution has had a chance to soak into the mold and mildew, power up your pressure washer.
Using a powerful tip, hold the pressure washer about 10-12 inches from the concrete and begin blasting. The mold should break up and wash away very quickly, and you should be left with clean, fresh looking concrete.
To avoid streaking, pressure wash the entire walkway in smooth, overlapping strokes to remove any other dirt or mildew buildup.