Power Washer Detergents - SD-927 is a non-hazardous biodegradable additive for use in hot water pressure washers and heaters. SD-927 helps prevent hard water scale build-up in soils and leaves a protective coating. Each small container (<1-lb.) treats up to 20,000 gallons of water. All ingredients are on the Food and Drug Administration Generally Recognized As Safe (GRAS) list. Just put the container in your feed tank and your water will be ready to use.