Contamination or pollution of a water system is usually brought about by a cross-connection to any systems containing auxiliary water supplies which may be polluted or contaminated; irrigation systems which may be polluted or contaminated with fertilizers, pesticides or other objectionable materials. Thus, using a hose-attached sprayer for application of pesticides, solvents, cleaning products, etc; flushing a car’s cooling system with a garden hose; or filling a swimming pool can all create situations where cross-connection can occur. Without proper protection, devices as useful as your garden hose have the potential to poison your home’s water supply. In fact, over half of the nation’s cross-connections involve unprotected garden hoses!