Source of Pesticides: The term "pesticide" includes all chemicals that are used to kill or control pests. This includes herbicides (weeds), insecticides (insects), fungicides (fungi), nematicides (nematodes), and rodenticides (rat poisons). Groundwater supplying wells may contain pesticides that have been leached from the fields by rain, melted snow, and irrigation water. Normal surface water runoff can allow pesticides to make their way into lakes and reservoirs, as many pesticides are used for surface treatment on farms, nurseries and golf courses. Excessive or improper application of pesticides can impact the drinking water. Improperly dumping of these chemicals and accidental spills can result in water contamination also. Water penetration into the ground from rain and snow melts can carry the pesticides deeper into the soil and into underground water supplies. Cleanup of groundwater contaminated by pesticides often is impossible, and the contamination may last for many years.

Health Effects of Pesticides: When pesticides are found in water supplies, they normally are not present in high enough concentrations to cause acute health effects such as chemical burns, nausea, or convulsions. Normally the concern is primarily for their potential for causing chronic health problems. These include cancer, birth defects, genetic mutations, or other problems such as damage to the liver or central nervous system. There are many hundreds of pesticide compounds, and extensive tests and studies of their effect on humans have not been completed.

How to Remove Pesticides: A WECO activated carbon backwashing filter is one of the most effective ways of removing organic pesticides from contaminated water supplies. Activated carbon adsorbs the pesticides from the water as it passes through the filter. A whole-house filter is recommended so every faucet, sink and shower will have purified water. A WECO reverse osmosis filtration system will remove all types of pesticides including metal-based pesticides like copper sulfate and arsenic.