The Danger and Treatment of Pesticides in Well Water

The Safe Water Drinking Act describes a contaminant as any substance other than water molecules that are present in your well water. There are four types of contaminants that may be found in well water, these include:


  • Physical Contaminants: These primarily impact the appearance of water. Examples include sediment or organic material suspended in the water.
  • Biological Contaminants: These include bacteria, viruses, protozoan and parasites
  • Radiological Contaminants: Chemical elements that are radioactive and can occur naturally in the soil like radon and uranium
  • Chemical Contaminants: These can be naturally occurring or man-made. Examples include nitrogen, bleach, salts, metals, toxins produced by bacteria, and human or animal drugs


While no natural water is completely free of contaminants, some are harmless when ingested. Others like calcium or magnesium are simply a nuisance. Some, like pesticides can pose a serious danger to your health depending on the amount and length of time of exposure.


Let's look at the dangers and treatment of pesticides in your well water.


First, What are Pesticides?

Pesticides are a group of chemicals used to kill or control pests. These can include weeds, fungi, rodents, insects and nematodes. They are toxic by design and if found in your water well, you should not use well water for drinking, bathing or cooking until they're removed.


Pesticide contamination is widespread. A study published on 2006 by the US Geological survey found atrazine, a widely used pesticide in the U.S, was found 90% of the time in streams in agricultural areas and 70% of the time in streams in urban areas and was also frequently detected in ground water.


Because groundwater moves slowly, pesticides can sometimes not appear in water wells until decades after application, depending on the pesticide used and the geological conditions. Because of this, even pesticides that have been banned may still appear in water supplies.


There are four main categories of pesticides, each containing a number of different chemicals:


  • Herbicides used to control weed growth
  • Fungicides used to control mold and mildew
  • Insecticides used to control insects like roaches or termites
  • Nematocides used to control various types of worms


How Pesticides End Up In Well Water

Pesticides can enter the water supply in a number of different ways. Pesticides are often used for surface treatment on farms, nurseries and golf courses. Normal surface runoff can carry these pesticides into lakes and reservoirs where they can then make their way into groundwater supplies. Water penetration into the ground after a rain shower or snow melt can also carry pesticides into the ground where they slowly make their way into aquifers.


When handling these chemicals it's important to follow proper safety procedures. Improper dumping or accidental spills can result in contamination. Excessive or improper application of pesticides on a property with a private well can result in contamination.


Safe Use of Pesticides Around Your Well

Pesticide contamination can be greatly reduced by proper application. Here are some tips for using pesticides near your water well:


  • Read the label carefully before each use. Pay attention to the Environmental Hazards section on the label.
  • Choose pesticides that break down quickly in the environment whenever possible
  • Select pesticides that do not move easily once they've been applied.
  • Don't ever apply pesticides when it's raining or about to rain.
  • Avoid applying pesticides to hardscape surfaces where they can easily wash into storm drains.
  • Whenever possible leave an untreated area along walkways and in drainage areas.
  • When cleaning up, make sure the rinse water will not contaminate waterways.
  • Pesticides are classified as hazardous waste. Never improperly dispose of pesticides down storm drains or into the sewer system.


The Health Effect of Pesticide Exposure

The health effects of pesticides are wide-ranging. It depends on factors including level of exposure and the length of time you are exposed.


Short term high-level exposure can result in immediate issues like vomiting, stomach pain, acute gastrointestinal distress, headaches, dizziness, eye irritation and at extreme levels, seizures. Long-term exposure to low levels of pesticides has been connected to liver and lung cancers, deformities in fetuses, and certain genetic mutations.


Treating Your Water for Pesticide Contamination

If your well water tests positive for pesticides don't panic! Treatment options are available that can remove them from your water supply. Reverse osmosis and granulated charcoal filtration are both affordable, effective treatments for removing pesticides.


Reverse Osmosis: These systems push water through a permeable membrane that allows water molecules to pass through, but blocks larger ions like those found in pesticides. RO systems are typical “point-of-use” systems found in the kitchen, near the sink. RO systems are efficient but smaller, inexpensive systems typically only treat a few gallons per day. Recent improvements in RO membrane technology allow more expensive systems to produce 100+ gallons per day.


Granulated Activated Carbon: GAC filters are relatively inexpensive and very easy to use. They remove pesticides when the contaminant sticks to the carbon, coal, or charcoal. These systems are typically also point-of-use systems. Filtered GAC pitchers are inexpensive and effective at removing pesticides. Change filters based on the manufacturer's instructions to maintain their efficiency.


At Skillings and Sons, we have a number of treatment options available both as point-of-use systems and whole-house point-of-entry water treatment systems. If you need more information, your local health department can be a valuable source. Or simply give us a call! We're always happy to answer your questions and arrange for testing of your well. If pesticides are found in your drinking water give one of our specialists a call to discuss all of your options.