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Monitoring Program

Making Sure Your Water Meets Drinking Water Standards
The Oro Valley Water Utility is responsible for ensuring that the water is safe, clean, and meets all local, State, and Federal drinking water health standards.

Drinking Water Rules Overview
The federal government authorizes the United States Environmental Protection Agency (USEPA) to set drinking water standards to protect the drinking water supply. This is accomplished by limiting the levels of certain chemicals or microorganisms that can adversely affect public health and are likely to be present in the water. The Maximum Contaminant Level (MCL) and Action Level (AL) are the health standards established by the USEPA that public water systems, such as the Oro Valley Water Utility, must meet to ensure safe drinking water. The MCL or AL is the highest level of a contaminant that is allowed in drinking water.

Once EPA develops a new standard, the rule is sent to the Arizona Department of Environmental Quality (ADEQ) to adopt and build upon drinking water standards based on Arizona laws and rules. In Arizona, ADEQ has primacy for drinking water rules and programs. This means the USEPA has granted ADEQ the right and responsibility to oversee these programs. Under the ADEQ Primacy agreement, Federal drinking water rules are incorporated into the Arizona Administrative Code where they then become enforceable by the state.

While ADEQ adopts, builds upon, and enforces drinking water standards, local governments and private water suppliers, like the Oro Valley Water Utility, have direct responsibility for the quality of the water that flows to your tap. The Oro Valley Water Utility tests and treats the water provided to customers, maintains the distribution systems that deliver water, and reports on water quality to the state. ADEQ provides technical assistance to water suppliers and can take legal action against systems that fail to provide water that meets these standards.

How often are Oro Valley Water sources tested to comply with the Drinking Water Regulations?  
Monitoring requirements, including the frequencies and locations, are specified within the drinking water regulations. In general, monitoring is required throughout the water delivery system. Water samples are taken at representative location in the distribution system, at private residences, and at the Entry-Point-to-the-Distribution-System (EPDS).

The monitoring frequencies are dependent on the results of the previous sampling events. More frequent monitoring is implemented when a level approaches the MCL in order to make the necessary adjustments to prevent an MCL exceedance, including shutting the well down. With ADEQ approval, a monitoring reduction is used when a contaminant is not detected over specified time period.

How will I know if a contaminant is found in my water?
Every summer, the Oro Valley Water Utility sends you an Annual Water Quality Report (also known as the Consumer Confidence Report, or CCR). The results contained in the report are based on the compliance data that was collected from the previous year to comply with the Drinking Water Rules. In 2010, The Oro Valley Water Utility sampled, analyzed, and reported 5,891 drinking water results. We are pleased to annouce that all compliance results were below the MCLs.

ADEQ also requires that the Oro Valley Water Utility give you public notice should our water supply violate drinking water standards. You will be given information about what is being done to correct the situation.