Potable (Drinking) Water

The City operates a Water Treatment Plant near Highway 12 (Jameson Canyon Road) to produce drinking water that meets the highest quality standards set by state and federal regulations. There are two treatment processes at the Plant: a conventional sedimentation and filtration treatment process, and a second, state-of-the-art membrane filtration process. Together the two processes produce up to 5.5 million gallons of potable water each day for residents and businesses in our water service area, which extends from the Napa/Solano County line to Soscol Creek just north of the Napa Airport.

Backflow Prevention Program

To protect the safety of our community's drinking water, all commercial and industrial businesses in American Canyon are required to install and regularly test their backflow prevention devices. These devices stop water from flowing in reverse from a potential contamination source back into the public water supply, which poses serious health risks. Ensuring backflow prevention devices are tested annually and functioning properly is mandated by Municipal Code 19.51.060(12) and is essential to maintaining clean, safe water for residents.

All backflow prevention devices must be tested annually before January 1 by a third-party certified tester. These mechanical check valves prevent water from flowing backward and require professional verification to ensure proper function. American Canyon's Water Division maintains records of all devices and sends annual notifications by mail to remind property owners about required testing.

Test results are submitted to the State Water Resources Control Board (SWRCB). American Canyon's Public Works Department, in coordination with the SWRCB, oversees compliance with these requirements. While the City sends notifications to non-compliant property owners, current practices do not include penalties for non-compliance.

2025 Approved Backflow Testers(PDF, 89KB)

Backflow Prevention Test Form(PDF, 107KB)

Disinfection Byproducts (THMs)

To protect drinking water from organisms that can cause disease, water providers — including American Canyon — use disinfectants. When these disinfectants mix with natural materials in the water, they can create chemicals called disinfection byproducts (DBPs).

DBPs tend to form more during hot weather or when water sits in pipes or storage tanks for an extended time. In neighborhoods that are farther from treatment and storage facilities, water spends more time in the system and DBPs have more time to form.

American Canyon conducts more than 500 tests each year across its entire water system to proactively identify and address any areas of concern. In the course of that testing, our team has identified the presence of a specific DBP known as Trihalomethanes (THMs).

The average level of THMs in American Canyon’s system meets the strict regulatory limits set in place at the state and federal levels. However, there have been a few incidents where levels temporarily exceeded the designated limit. Any time this occurs, the City sends a notice to customers in the area where the limit was exceeded. Immediate steps are taken to address excess DBPs, and drinking water remains safe for customers to drink. Those notices are shared below our FAQs.

FAQs

Is my water safe to drink?
Yes, American Canyon’s water is safe for the general population to drink. If you have a medical condition that suppresses your immune system, or if you are worried about the quality of your tap water, you can consult your doctor for recommendations.

How is American Canyon working to prevent the occurrence of DBPs?
Our team has begun using new methods to more effectively remove organics from the water treatment plant, which reduces the potential for DBP formation. We are also in the planning stages for key improvement projects, including new filtration systems and more sophisticated system controls. Both will help reduce DBPs.

What is a THM, and how is it formed?
Trihalomethanes (THMs) are a byproduct of the water treatment process. They are formed when natural organic material, such as decaying plants or dirt, reacts with chlorine used to treat the water. This reaction produces “disinfection byproducts,” the most common of which are THMs.

How are THMs regulated, and what levels are in American Canyon’s water?
Water quality regulations require our water to comply with a maximum contaminant level of 80 parts per billion (ppb). In 2024, the average level detected in American Canyon’s system was 70.8 ppb — meeting water quality regulations. However, one specific sample showed THM levels that exceeded the maximum level. Any affected customers are notified when this occurs.

One part per billion is equivalent to one drop of water in an Olympic-sized swimming pool. Amounts detected are extremely small in volume and safe for the general population.

I’ve never heard of disinfection byproducts before, so why am I hearing about this now?
Technological advances allow water providers to detect and report on an expanded range of chemicals. With those advances, federal and state regulations continue to become more stringent. American Canyon continues to expand its testing methods and frequency to meet these strict requirements.

January 2023 Notice

April 2022 Notice

January 2020 Notice

PFAS

PFAS are a group of man-made chemicals that have been used in everyday products — including clothing, cleaning products, non-stick cookware, firefighting foam and carpet — for over 70 years. Some common PFAS include PFOA, PFOS and GenX.

PFAS are found in many products, and they don’t break down easily in the environment. They can end up in soil, air and water, including some drinking water sources. Scientists and water experts have monitored PFAS for years, but only recently have testing methods become advanced enough to detect PFAS in incredibly tiny amounts: parts per trillion (PPT). One PPT is equivalent to one grain of sand in an Olympic-size swimming pool.

The U.S. Environmental Protection Agency (EPA) and the State of California are working to reduce PFAS in drinking water. California has set Notification Levels (when water providers must notify regulators and customers) and Response Levels (when providers may need to take action) for several PFAS.

American Canyon regularly tests its drinking water and has not detected any PFAS in its supply. We continue to monitor our water to ensure customers have 24/7 access to safe, reliable drinking water.

Discolored Water

Discolored water (ranging from light yellow to dark brown) is typically caused by a disturbance of pipeline sediments — including naturally occurring particles and minerals — in the water main. Any of the following circumstances may have caused sediment to be disturbed:

A nearby water hydrant may have been knocked over due to a vehicle collision or may be in use to fight a fire.
There may be some pipeline repair work (or construction activity, including emergencies such as main breaks) in the area and some valves may have been closed for this work. Your service connection from the main to the meter is sometimes disturbed by construction activities of contractors or other utilities.
Changing direction of water flow that occurs when the City switches its water source between American Canyon’s Water Treatment Plant and our supplemental sources from Vallejo Water and/or Napa Water.
Aging plumbing — Buildup on galvanized steel home plumbing can produce particles or reddish-brown water, particularly noticeable when the tap is first turned on. The buildup can also create problems of insufficient flow within the home.
Issues with your hot water heater, including a defective dip tube or need for maintenance, are also a common source of particles in home plumbing systems.

Despite its appearance, discolored water does not indicate that the water is unsafe or that the integrity of the water main is compromised. A disinfectant residual is maintained at all times to ensure that the water is safe for household use, including cooking and drinking. For aesthetic reasons, you should avoid doing laundry until the water clears up. If you have done laundry and experience issues, please call (707) 647-4550 and our team can provide a product to help remove any stains from your laundry.

If you notice discolored water in your home or business, run water at the hose bibs outside for several minutes and then run cold water inside for at least 5 minutes until the water is clear.

Reporting a Problem with your Drinking Water

Before reporting a problem, please note whether your concern is with the water’s color, taste, odor, or something other, and be prepared to answer the following questions:

Is the problem in the hot water, cold water, or both?
Is the problem observed at all faucets?
Do neighbors see a similar problem?
Is there construction activity nearby?
Have you run water at the hose bibs outside for several minutes and then run cold water inside for at least 5 minutes and the water is still not clear?

Call (707) 647-4364 or (707) 995-8674 after-hours.

Water Taste or Odor

Most peculiar tastes or odors fall into one of the following three categories:

CHLORINE - At the treatment plant, the city adds a small amount of chlorine to the drinking water as a disinfectant, to kill or prevent the growth of harmful germs. Regulations limit the amount of chlorine so that it keeps the water safe to drink. If you are sensitive to the chlorine taste, an easy way to get rid of it is to let water sit in a glass for a few minutes. Then put the water in a covered container and chill it in the refrigerator. Almost all household water filters can reduce or remove chlorine.
EARTHY/MUSTY - Sometimes algae are not controlled by the usual treatment process and naturally make substances that create an earthy or musty smell but are not harmful in the small amounts found in drinking water. This happens more often in the warmer months when algae growth may increase in our surface water sources.