Drinking Water

A Water QuALITY division FOCUS


Scottsdale’s Drinking Water Quality Monitoring Program


Scottsdale water is extensively tested to ensure that it remains safe for consumption by our customers.  Within the Safe Drinking Water Act, there are various drinking water rules and regulations that water systems must comply with.  The Environmental Protection Agency (EPA), Arizona Department of Environmental Quality (ADEQ) and Maricopa County work together to enforce drinking water regulations. 

In order to maintain compliance with regulations, routine monitoring is done at the Scottsdale’s water treatment facilities, well sites and in the distribution system.  Additionally, when a new water source is brought into service, extensive testing is done to ensure it meets guidelines established by EPA.

Routine Monitoring  

Turbidity: Turbidity is a measure of water’s clarity which is improved through the water treatment process. Turbidity is caused by suspended matter such as organic and inorganic particulates, silt, algae or tiny microorganisms. Water that is highly turbid is more likely to contain undesirable microbial contamination.  To ensure that safe turbidity levels are achieved and maintained, turbidity is measured continuously at our surface water treatment facilities.

Chlorine: Chlorine is used as a disinfectant to ensure the destruction of potentially harmful microbes and to control microbial activity within our distribution pipes.  Chlorine levels are monitored continuously at our water treatment plants and in the distribution system to ensure that safe, adequate levels are maintained. Scottsdale’s goal is to have a chlorine residual between 0.8 parts per million (ppm) and 1.2 ppm in water distributed to customers.

Bacteriological/Microbial: Every month the City of Scottsdale tests over 150 sites within the distribution system for Total Coliform and E.Coli bacteria in order to ensure that microbial contamination has not occurred. Total Coliform bacteria are considered a useful indicator of microbial contamination because these bacteria are impacted by water treatment and disinfection in a manner similar to most bacterial pathogens and many viral enteric pathogens. Total Coliforms are used to determine the adequacy of water treatment and integrity of the distribution system.

Disinfection Byproducts (DBPs): On a quarterly basis, levels of disinfection byproducts are measured within the distribution system at various sites throughout the city.  For more information on DBPs go to Hot Topics.

Nitrate: Nitrate is measured annually at all groundwater sources and at least quarterly at our surface water treatment plants. For groundwater sources that have nitrate levels greater than 5 parts per million (ppm), testing is performed quarterly.

Arsenic: Arsenic occurs naturally at varying levels in our water sources. Arsenic is measured quarterly or more frequently at our arsenic treatment facilities or where water is blended to meet the arsenic standard.  Sources that are at lower risk for arsenic contamination are tested annually. For more information on arsenic go to Hot Topics.

Inorganics: Other inorganic contaminants, including but not limited to fluoride, chromium, barium, thallium and mercury are measured at each water source on an annual basis.

Organics: Organic contaminants including herbicides and pesticides are measured every three years at each water source, Volatile Organic Compounds (VOCs) such as gasoline derivatives and solvents are measured annually or more frequently. If a regulated organic compound is detected in our drinking water, federal regulations require quarterly monitoring of that contaminant in order to make certain that the concentration does not rise to unsafe levels.

Radionuclides: Radiochemical contaminants including gross alpha emitters and uranium are measured quarterly when a new water source is brought into service.  Once baseline levels are established, monitoring is performed every three, six or nine years depending on the water source. Most Scottsdale water sources require monitoring every six years.

Lead & Copper: Lead and Copper testing is performed in 50 Scottsdale residences every three years.  Residences that participate in this monitoring program are selected based on criteria established in the Lead and Copper Rule.   For more information on Lead and Copper in drinking water go to Hot Topics.