FAQ: PFAS Water Testing for Irrigation, Livestock, and Household Water Systems

Private water systems such as wells, springs, and cisterns are common in communities located outside public water supply service areas. Farm water resources can include groundwater (e.g., wells or springs) or surface water sources (e.g., ponds, lakes, or streams) used for irrigation and animal watering. Unlike public drinking water systems, the protection, maintenance, and testing of a private water system and farm water resources are the responsibility of the owner or user. Laboratory testing is the only way to know for sure if PFAS have contaminated water sources.

How can farm water resources and private water systems be contaminated with PFAS?

Common sources include industrial discharges, aqueous film-forming firefighting foam use in the past, PFAS-contaminated landfill leachate, the application of PFAS-contaminated biosolids on agricultural fields, etc. Because PFAS break down slowly and are easily transported with water, they can be transported through the soil with infiltrating rainwater, snowmelt, or irrigation water and reach groundwater aquifers. They can also be transported via surface runoff to nearby surface water sources. Groundwater naturally flows into lakes and streams through a process known as baseflow, which helps maintain water levels during dry periods. Similarly, groundwater may be the main water source for ponds through springs or subsurface flow. This groundwater-surface water interaction can be a hidden PFAS pathway to surface water sources, especially if a local aquifer is impacted by potential PFAS sources.

How PFAS move in the environment is influenced by a lot of factors, such as PFAS chemical properties, soil type, underlying geology, groundwater depth, flow direction, and site-specific conditions, among many others. Proximity to PFAS sources alone does not mean your water sources are contaminated. However, it may be worth considering testing if there is a confirmed PFAS issue on the farm or in the surrounding areas.

What laboratories test for PFAS?

Since PFAS are emerging contaminants, only a handful of laboratories in Pennsylvania are accredited by the Department of Environmental Protection (DEP) to test for PFAS in water.  Laboratories may provide sampling kits containing bottles and instructions for collecting, handling, and shipping samples, specific to the analytical method.  Currently, PFAS testing can cost approximately $250 to $500 per sample, depending on the type of sample and method used.  Please refer to the PFAS Testing Services and Laboratories Directory fact sheet for a full list of accredited laboratories. Ask the laboratory for Method 537.1 or 533, as these methods will include a variety of PFAS compounds, including those that have state and federal drinking water regulations.

Where should I collect water samples for analysis?

Where to collect your water samples will depend on the goal for testing. If the goal for testing is to evaluate PFAS levels in water used for irrigation or animal drinking water, then the focus should be given to the corresponding water sources.

If you are assessing PFAS levels in your private water source itself, i.e., the well, spring, or cistern, it is recommended to collect your sample before any in-house water treatment devices such as filters. Ideal locations might be from your well tank spigot or from an outdoor spigot that bypasses any water treatment devices you may have. When collecting a sample from an outdoor faucet that bypasses in-house treatment, if possible, remove hoses attached to the spigots before collecting the sample, since materials used to make the hose may contain PFAS compounds that may contaminate your sample.

If you are trying to assess PFAS exposure from the water used for cooking and drinking, it is recommended to collect samples at the kitchen faucet. This will provide you with PFAS levels after any existing in-home water treatment devices. Always collect your sample from cold water if using an indoor faucet.

How should I collect my water sample to avoid cross-contamination?

Follow the sampling instructions you receive from the laboratory and only collect your samples in the bottles they provide. Laboratories may include nitrile gloves that should be worn during sample collection.  Some sample bottles may contain a preservative; therefore, double-check the sample guidelines provided before rinsing out the containers.

Laboratories may also include extra samples for quality control. Below are some terms you may come across and what they mean:

Field blank sample – This is an optional sample used by the labs to verify that any PFAS detected in your private water supply is indeed from your water and not from sampling containers, contamination during sampling, handling, or shipping. Field blank samples can be PFAS-free water in a bottle supplied by the laboratory that is simply opened and exposed to air at the sampling site during sample collection, then sealed back. The other field blank option is where the laboratory may give you a second container to transfer the PFAS-free water into and then seal. Both these options are used to assess any cross-contamination during sample collection. Some labs will include a field blank in the testing costs, but it can be an added cost. 

Duplicate sample – this is a second water sample collected from the same sampling location, under identical conditions. It is used as a quality control measure on the accuracy of the sampling and laboratory analysis process. If the laboratory needs a duplicate sample, they will include an extra sample bottle and instruct you to fill it with your water sample.

How are collected samples preserved?

Keep samples cold from the moment of collection using ice or provided ice packs to preserve samples during shipping to the laboratory. PFAS water samples have a hold time of 14 days; however, most laboratories will require overnight shipping of collected samples to ensure they are preserved properly.

How do I interpret test results?

It may take a couple of weeks before you get your test results from the laboratory. Private water systems are not required to meet state or federal drinking water standards; users are encouraged to compare their test results against current Maximum Contaminant Levels (MCLs). There are no state or federal guidelines for water used for irrigation or livestock watering. For general help interpreting your test results, please refer to the What Do the Numbers Mean fact sheet, use our Drinking Water Interpretation Tool (DWIT), or call your local Extension Educator.