Water pollution can occur in wells. The ground aquifer can become contaminated by chemicals and invade well water sources. People using the well can ingest the chemical through drinking, contact the chemicals while bathing or inhale the chemicals from water steam. Potential water contaminants include pathogens, such as bacteria, parasites and viruses; heavy metals, including lead, arsenic and mercury; non-metallic inorganics including insecticides and asbestos; synthetic organic compounds; radioactive substances including radon, radium and uranium; and chlorine and trihalomethanes