Water Quality Issues and Home Water Testing
MARSHFIELD, Mo. — What a person does in and around their home can affect water quality below the soil surface and in nearby water sources, warns Bob Schultheis, natural resource engineering specialist with University of Missouri Extension.
“Drawing a simple aerial view map of your home will help identify important characteristics, such as soil type, geology, depth to groundwater, and nearness to surface water. The completed map will show the locations of important features and identify activities in and around your home that may pose risks to your health and the environment,” says Schultheis.
How does soil type affect groundwater?
Groundwater is the water below the surface of the earth that, from the water table down, saturates the spaces between soil particles, sand and gravel layers, or fills cracks in underlying bedrock. According to Schultheis, soil particle size influences which pollutants can reach groundwater.
“Clay soils made of small particles, slow the downward movement of water and sometimes impede water movement completely. Sandy soils made of large particles, allow rapid water movement, and silty soils occupy the middle range,” says Schultheis.
Soils made of large particles pose the greatest risk because water seeps downward through them more readily without filtering out or decomposing pollutants. The ideal soil is a mix of midsize particles to allow infiltration and tiny particles, like clay or organic matter, to slow water movement and filter pollutants.
“Soils that are less than three feet deep present the highest risks for groundwater contamination,” says Schultheis.
The depth of water tables fluctuate throughout the year but are usually highest in the wet months of spring and late fall. Usually, the water table that is less than 10 feet from the surface presents a higher risk for groundwater contamination.
Tests of water supplies look for an indicator of human or animal waste – coliform bacteria. Coliform bacteria also could come from natural sources such as soil or decaying vegetation. Some coliform bacteria are only present in fecal material, called fecal coliforms.
Always collect water samples for bacteria tests in a sterile container. Take a sample from an inside faucet with the aerator removed. Sterilize by flaming the end of the tap with a disposable butane lighter. Run the water for two minutes to clear the water lines. Do not touch or contaminate the inside of the bottle or cap. Carefully open the sample container and hold the outside of the cap. Fill the container to the line to allow mixing and replace the top. Refrigerate the sample and transport it to the testing laboratory within 36 hours (preferably in an ice chest).
“Bacterial contamination is common,” Schultheis explains. “More than 40 percent of private water supplies have coliform bacteria contaminated based on recent studies. Spring water supplies are the most frequently contaminated, with more than 70 percent containing coliform bacteria.”
If water is contaminated, boil it; it is extremely effective as a disinfectant. Vigorous boiling for three minutes kills bacteria, including disease-causing organisms and giardia cysts.
For more information, contact any local MU Extension office or see the MU Extension water quality guide sheets (EQM101F and WQ102) online at https://www.extension.missouri.edu/.