Well Water Quality

Public water systems are regulated by county, state, or federal government, usually depending on the number of connections the water system serves. Public water systems are required to provide to their customers, at least once a year, a notice of water quality.

While many states have adopted the safe drinking water standards of the federal government (United States Environmental Protection Agency-USEPA), the State of California has adopted its own regulatory safe water standards for public water systems that are at least as restrictive as those of the USEPA.

While the standards established for public drinking water systems are not enforceable for private well water, they can provide a parallel indication of the quality and safety of water that comes from private wells. Standards associated with public drinking water supplies are:

• MCL is the Maximum Contamination Level permissible in public drinking water supplies. MCLs are established based on a number of considerations, including health risk, technological feasibility, treatment costs to water systems, and public hearings.
• PHG is the Public Health Goal established for public drinking water based on health risk assessment alone and is the level at, or below which, health effects are not expected to occur from a lifetime of exposure.

Click here for well water testing information.

Click here for information on well disinfection.

For more information on drinking water wells and septic systems in Sonoma County please visit the Well and Septic page or contact Permit Sonoma Well and Septic at (707) 565-2849.

PFAS (Per and Polyfluoroalkyl Substances)

PFAS (per- and polyfluoroalkyl substances) are a large group of human-made chemicals that have been used in industrial processes and consumer products since the 1940s. Because PFAS resist heat, water, oil, and stains, they have been used in products such as non-stick cookware, food packaging, stain-resistant fabrics, cosmetics, firefighting foams, and many industrial applications.

PFAS are often called "forever chemicals" because they break down very slowly in the environment and can accumulate over time in soil, water, wildlife, and people.

Most people are exposed to small amounts of PFAS through everyday sources such as food, drinking water, household dust, and consumer products. Studies show that most Americans have detectable levels of PFAS in their blood.

Resources for Private Well Owners and Interested Residents

To determine whether PFAS may be present in your well water, a water sample must be collected and analyzed by an accredited laboratory. PFAS sampling requires specialized collection procedures because samples can easily become contaminated by common environmental and household sources, potentially affecting the accuracy of the results. For this reason, private well owners interested in PFAS testing may wish to work with experienced environmental professionals or trained sample collectors. A few options in Sonoma County include (but are not limited to):

• Weeks Drilling & Pump Co.: https://www.weeksdrilling.com/
• Larbre Well and Pumps: https://www.larbrewellandpumps.com/
• Les Peterson Drilling & Pump Inc.: https://www.lespetersen.com/
• Jerry & Dons Yager Pump & Well Service: https://www.jerryanddonsyagerca.com/
• Hydrologic Water Treatment Services: https://hydrologicwaterservices.com/

Keep in mind that a single sample result represents only one point in time, and water quality conditions may change over time. Periodic sampling for PFAS and other potential contaminants may therefore be appropriate depending on local conditions and individual concerns.

Frequently Asked Questions

What are PFAS?

PFAS are a group of thousands of human-made chemicals that do not occur naturally in the environment. Two of the most widely studied PFAS are PFOA and PFOS.

Because PFAS resist grease, oil, water, and heat, they have been used in a wide range of consumer and industrial products, including: 

• Non-stick cookware
• Food packaging
• Water- and stain-resistant fabrics
• Carpeting
• Cosmetics and personal care products
• Firefighting foams
• Industrial manufacturing processes
• Pesticides

How do PFAS get into the environment?

PFAS have been widely used since the 1940s in many consumer and industrial products, including non-stick cookware, food packaging, stain-resistant fabrics, firefighting foams, cosmetics, and industrial manufacturing processes.

Because of their widespread use, PFAS can enter the environment through industrial activities, firefighting foam use, wastewater discharges, landfill disposal, and everyday use of PFAS-containing products. PFAS break down very slowly and can persist in soil, groundwater, surface water, and the food chain for many years, leading to their nickname, "forever chemicals."

Are PFAS harmful to human health?

According to the U.S. Environmental Protection Agency (EPA), scientific studies suggest that exposure to certain PFAS may be linked to adverse health effects. However, research is ongoing, and scientists continue to learn more about how different PFAS affect human health.

Many health conditions associated with PFAS exposure can also be caused by other factors, making it difficult to determine whether PFAS exposure is the direct cause of a specific health outcome.

If my family has been exposed to PFAS, will it affect our health in the future? 

At this time, scientists do not fully understand the long-term health impacts of PFAS exposure. If you believe you have been exposed to elevated levels of PFAS, discuss your concerns with your healthcare provider.

Your doctor can recommend appropriate health screenings and monitor any symptoms or conditions that may require medical attention.

Parents with questions about PFAS exposure and children's health should consult their pediatrician.

What can I do to reduce my exposure to PFAS? 

While PFAS are widespread in the environment, there are steps you can take to reduce future exposure:

Stay informed about local drinking water quality.

Consider using a water treatment system certified to reduce PFAS if PFAS are present in your drinking water.

Follow public health guidance regarding PFAS.

Limit the use of products known to contain PFAS when alternatives are available.

Maintain regular medical check-ups and recommended health screenings.

Maintaining a healthy lifestyle, including a balanced diet, regular physical activity, and routine preventive healthcare, remains one of the most important ways to support overall health.

I received a Consumer Confidence Report (CCR). What does it tell me?

Consumer Confidence Reports (CCRs), also known as Annual Water Quality Reports, provide information about your drinking water source, water quality testing results, and compliance with federal and state drinking water standards.  CCRs are available from your local water provider.

If you receive water from a public water system, your provider's CCR is the best source of information about the quality of your drinking water. If you use a private well, you will not receive a CCR and should arrange for periodic water testing to evaluate water quality.

I get my drinking water from a private well.  How do I know if it’s safe?

Private wells are not regulated or routinely monitored by government agencies or water providers. It is the responsibility of the well-owner to ensure that their drinking water is safe.

Routine water testing is recommended, particularly if you have concerns about PFAS or other contaminants. Professional sampling and laboratory testing can help reduce the risk of inaccurate results caused by sample contamination.

If PFAS are detected in your well water, you may consider installing a treatment system certified to reduce PFAS in drinking and cooking water.

According to the EPA, only negligible amounts of PFAS are absorbed through the skin. Activities such as showering, bathing, and washing dishes with water containing PFAS are unlikely to significantly increase health risks.

Well owners should also follow recommended maintenance practices and consult a licensed well professional when evaluating water quality concerns.

For more information about water filtration for PFAS, see guidance from https://www.nsf.org/consumer-resources/articles/pfas-drinking-water.

For more information about safely maintaining your well and concerns related to PFAS, work with a licensed professional to have the water well tested and treated if needed.   Testing the well yourself can provide false positive results due to cross contamination of the sample. 

For additional information on well testing and sampling in Sonoma County:  https://sonomacounty.gov/health-and-human-services/health-services/divisions/public-health/environmental-health/programs-and-services/well-water-quality/well-water-testing

Additional Resources

• U.S. Environmental Protection Agency (EPA)
  https://19january2021snapshot.epa.gov/pfas/basic-information-pfas_.html
• California State Water Resources Control Board, Division of Drinking Water (DDW)
  https://www.waterboards.ca.gov/pfas/
• U.S. Food & Drug Administration (FDA)
  https://www.fda.gov/food/environmental-contaminants-food/and-polyfluoroalkyl-substances-pfas
• U.S. Centers for Disease Control & Prevention (CDC ATSDR):
  https://www.atsdr.cdc.gov/pfas/site.html#gen