More than 5 million people in Arizona receive their drinking water from a regulated public water system. Currently, the Arizona Department of Environmental Quality oversees approximately 1,700 regulated public water systems with the help of local counties to ensure the quality of tap water meets or exceeds state and federal Safe Drinking Water Act standards.

While many people are unaware of it, there is a complex and extensive framework in place to ensure clean, safe drinking water is served by every public water systems in Arizona.

Protection of drinking water quality starts with an assessment of the drinking water source quality and continues through regulations that govern water system design and construction. Finally, drinking water quality is assured through scheduled tests required of all public water systems for a wide variety of potential contaminants. As a result of these regulations and continued testing, drinking water supplies in the United State are among the cleanest and safest in the world.

What is a Public Water System?
The term public water system refers to any water system that has 15 or more service connections (hook-ups) or serves 25 or more people. Water systems that serve less than 15 service connections or 25 people are considered private water systems and are not regulated by ADEQ. However, there are resources available to owners of private wells and these non-regulated systems.

Public water systems can be run by cities or towns, by federal or state agencies, by other political subdivisions like water districts and co-ops, or by private, for-profit companies. Regardless of the ownership, these systems must comply with all requirements of the Safe Drinking Water Act.

There are three different categories of public water systems in Arizona, based on the type of service they provide. These definitions are taken from Arizona Administrative Code R18-4-101.

• A "community water system" is one that serves 15 or more service connections used by year-round residents or that serves 25 or more year-round residents who use water for drinking, cooking, bathing and cleaning. Community water systems may also serve all the businesses and other water users within their boundaries.
• A "non-transient, non-community water system" is one that serves 15 or more service connections that are used by the same persons for at least six months per year, or serves the same 25 or more persons for at least six months per year. These water systems supply businesses where people may spend a large percentage of time, but these typically aren't a consumer's primary water source. Examples include schools and hospitals.
• A "transient, non-community water system" is one that serves 15 or more service connections, but does not serve 15 or more service connections that are used by the same persons for more than six months per year; or one that serves an average of at least 25 persons per day for at least 60 days per year, but does not serve the same 25 persons for more than six months per year. Examples include businesses where the average person will not be drinking the water for long periods of time, such as truck stops, restaurants or campgrounds. Because of the short exposure times involved, typically these systems only monitor for acute contaminants such as nitrates or bacteria.

Community and non-transient, non-community water systems make up approximately 1,000 of the approximately 1,700 water systems in Arizona.

Water Conservation
Because we live in an arid state, planners must work to balance available water resources with the increasing demand for water. The least expensive way to provide water for growth and to assure an adequate supply for the future is through wisely managing and carefully using the supplies we already have.

The most effective water conservation efforts are those that are voluntarily and willingly accepted as a shared responsibility between citizens and their communities.

Water conservation links

• Arizona Department of Water Resources
• EPA brochure Using Water Efficiently: Ideas for Residences

Resources and Recommendations for Private Well Owners
Although ADEQ does not regulate private wells, the department encourages well owners to educate themselves about water quality and drinking water health issues. Well owners should investigate adjacent land uses and local geology to determine which, if any, contaminants could be affecting their well.

ADEQ strongly encourages private well owners to collect periodic water samples to test for bacteria and other contaminants. The Arizona Department of Health Services Environmental Laboratory Licensure Program can provide information about proper laboratory procedures and laboratories certified to perform drinking water analysis. The ADHS Environmental Laboratory Licensure Program can be reached at (602) 364-0720.