Testing your well water

Keep an eye on water quality in existing wells by testing it twice a year. Although you cannot have your water tested for every pollutant, some basic tests indicate whether or not problems exist.

At a minimum, test your water annually for bacteria and nitrate. Where the well draws from sandy materials or granite bedrock, test once for corrosiveness. Good initial tests for a private well also include tests for hardness, alkalinity, pH, conductivity and chloride.

In addition, you may conduct a broad scan of your water for a number of contaminants. Some mail-in labs offer a screening for metals, inorganic chemicals, volatile organic chemicals, herbicides/pesticides and coliform bacteria for $80 to $120 per chemical.

The results may not include contaminants that could be near your farm: for example, the most commonly used pesticides in your area. Test for contaminants that most likely will be found at your farmstead. Test for lead if you have lead pipes or soldered copper joints. Test for volatile organic chemicals (VOCs) if they have been used nearby or if there has been a spill of oil, petroleum or solvent. Although testing for pesticides can be costly (often $80 to $100 per compound analyzed), the expense may be justified if:

• Your well has nitrate levels of more than 10 milligrams per liter (mg per liter) (reported as nitrate-nitrogen, NO₃-N) or 45 milligrams per liter (reported as nitrate, NO₃);
• A pesticide spill has occurred near the well, or backsiphonage has occurred;
• Your well is shallow, has less than 15 feet of casing below the water table or is located in sandy soil and downslope from irrigated croplands where pesticides are used.

For $70 or more, commercial labs test your drinking-water supply for atrazine and other pesticides. (Contacts and References.)

You can seek more advice on appropriate tests to run from your local MU Extension center or health department or your DNR regional office.

You should test your water more frequently if:

• Your family experiences unexplained illnesses;
• 
  Anyone in your family is pregnant;
• You notice changes in livestock or poultry performance;
• Your neighbors find a particular contaminant in their water;
• You note a change in water taste, odor, color or clarity;
• You have a spill or backsiphonage of chemicals or petroleum products near your well or on your farmstead;
• You apply chemicals, manure or whey to your fields within 100 feet of your well; or
• Your livestock operation inspectors require it.

You can have your water tested by both public and private laboratories. A list of certified labs is available from the Missouri DNR or your local MU Extension center.

Follow the lab's instructions for water sampling to ensure accuracy of results.

Use only the container provided, and return samples promptly. Bacteria sample bottles are sterile and must be returned within specified time limits.

Because many materials, including bacteria and nitrate-nitrogen, are present naturally in minor amounts in groundwater or can vary seasonally, contact a specialist for help in interpreting test results.

Bacteria and nitrates are two important indicato

rs. At excessive levels, they can cause health problems themselves and also may suggest problems with the well's location or construction. Hardness and pH indicate how corrosive the water may be to your plumbing system.

The chloride level also may indicate other problems. In Missouri, most chloride comes from such human activities as road salts and waste disposal.

In most areas of Missouri, a level of more than 10 milligrams per liter suggests that land use is somehow affecting your well.

Keep in mind that activities off your farm can affect your groundwater. Chemical spills, changes in land use and the presence of landfills increase the chance of pollutants getting into your water. If your water has a high nitrate or bacteria level, talk with a specialist about the need for additional testing.