Water Quality

Public water systems that serve Prescott, Prescott Valley, and Chino Valley, and private water companies that have at least 15 service connections or serve at least 25 people per day for 60 days of the year are required to meet drinking water quality standards set by the U.S. Environmental Protection Agency (USEPA), as authorized by the federal Safe Drinking Water Act.  The standards are expressed as Maximum Contaminant Levels (MCLs) for over 90 contaminants as well as other treatment requirements for public drinking water.  The MCL is the maximum permissible level of a contaminant in drinking water that is delivered to any user of a public water system.  

The frequency of sample collection is determined by federal and state regulations and is based on many different parameters such as type of water source and number of people served, as well as past and current analyses of the contaminant to be tested.  The City of Prescott reports that sample frequency can range between 1 month and 3 years. 

Public water systems are required to provide customers with a yearly summary report of their compliance with the standards.  Moreover, water customers must be alerted if there is a risk to public health, including notifications if the water does not meet drinking water standards, or if the water system operators fail to test its water.

How to review the Annual Water Quality Reports for your city or town:

• Prescott: Go to Prescott’s Water Quality Reports webpage.
• Prescott Valley: Go to the Prescott Valley website, select “Utilities” and then “Water Quality.” 
• Chino Valley: Please contact the town at 928-636-3400.

If your water is provided by a smaller private water company, please contact their office (or designated manager) to inquire about their annual water quality report, or if exempt, results from any testing that has been conducted.

USEPA regulations that protect public water systems do not apply to privately owned wells; owners of private wells are responsible for ensuring that their well water is safe from contaminants.  If you are on private well water, please see the other CWAG Water Quality Topics, including “IF I’M ON PRIVATE WELL WATER, WHAT ABOUT MY WATER QUALITY AND WHAT ARE THE TESTING RECOMMENDATIONS?”

As a private well owner, you are responsible for the care and upkeep of your well.  The Arizona Department of Health Services (AZDHS) recommends that to protect your health, your well water should be tested for contaminants based on the schedule in the table below.  Please note the table also lists the Maximum Contaminant Level (MCL), Secondary Maximum Contaminant Level (SMCL), or Maximum Contaminant Level Goal (MCLG) established by the U.S. Environmental Protection Agency (USEPA).  In contrast to the MCL which is an enforceable regulation, a SMCL is an established non-enforceable guideline to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor.  An MCLG is a non-enforceable public health goal. 

Test results from private wells should be compared to the MCL, SMCL, or MCLG for assessment of potential health risks.  Where results exceed these standards, you should discuss the results with local and state officials to assess the potential risks and/or consider treatment options.  Where the levels greatly exceed these standards, it may be appropriate to not use the water supply until corrective actions are taken.

ppb=parts per billion; ug/L=micrograms per liter; ml=milliliter; ppm=parts per million; mg/L=milligrams per liter.

AZDHS also recommends testing your private well when:

• There are known problems with well water in your area,
• You have found a high radon concentration in your home (test the air in your home every 7-10 years).  If you have found high radon concentrations in the air, consider testing your water for radon,
• You have experienced problems near your well (e.g., flooding, land disturbances, nearby waste disposal sites, and wildfires),
• You notice a change in water quality (such as color, taste, or odor), or
• If anyone in your family has an unexplained illness.

For more information, see: 

• AZDHS publication Protect Your Health, A Guide for Private Well Owners in Arizona,
• AZDHS webpage Test Your Well, Protect Your Family’s Health,
• University of Arizona Cooperative Extension publication Well Water Testing and Understanding the Results, and
• USEPA webpage National Primary Drinking Water Regulations.

You can contact a lab certified by the Arizona Department of Health Services (AZDHS).  To find certified labs, go to the AZDHS webpages:

• Test Your Well, Protect Your Family’s Health, and click on the link “Find a lab near you,” or
• List of Arizona Certified Commercial Drinking Water Laboratories to search by state or all states.

Note that the first AZDHS webpage above also has a link to participate in a free water testing program — you can click on the link to see if any free testing program is currently available.  You can also contact the Arizona Department of Environmental Quality to see if it is offering free testing; their phone number at the Phoenix main office is 602-771-2300.

Please consult with the certified lab you are considering or have chosen regarding the most appropriate analytical method for your contaminant(s) of concern.

Water filters are not monitored by the U.S. Food and Drug Administration.  CWAG recommends that you thoroughly evaluate and compare filtration options using multiple sources of information and especially for larger systems, obtain more than one reference.  There are three different certifications to look for on a label for a filter or filtration system; these organizations can also assist you in selecting a filter or system that meets your needs.  The three organizations, also accredited by the American National Standards Institute (ANSI), are:

• NSF International (National Sanitation Foundation International), an independent global organization that certifies many water treatment devices, 
• The Water Quality Association, another leading authority on water filter standards that provides third-party product certification, and
• Underwriters Laboratories (UL), also has water filter testing and certification programs.

Consumer Reports also evaluates and recommends water filters and publishes a Water Filter Buying Guide.

For more information on water filters and treatment, see the following publications: 

• United States Environmental Protection Agency (USEPA) Fact Sheet on Filtration Facts,
• USEPA Overview of Drinking Water Treatment Technologies, and
• Centers for Disease Control and Prevention Choosing Home Water Filters & Other Water Treatment Systems.