Arsenic – The EPA established a drinking water standard for arsenic in which water providers are to ensure that as of January 2006, no more than 10 parts per billion (ppb) of arsenic can be found in the drinking water delivered to customers. All of Metro Main’s wells are under 10 ppb. Two wells in Metro Hub and two in Metro Southwest have treatment systems to ensure compliance with the arsenic rule.
Water Hardness – The systems are interconnected in some areas so water is blended and concentrations may vary.
Fluoride and Sodium Levels – The systems are interconnected in some areas, so water is blended and concentrations may vary.
Treatment – The District does treat its water with chlorine. In 1994, when a few service areas tested positive for total coliform bacteria, the District began to add chlorine to eliminate any type of bacterial contamination that could occur in the water pipes. Since 1995, the District has not had further problems with bacterial contamination.
Additionally, a water treatment system is in place at the South Shannon well site. In 1994, the District detected traces, but not violations, of two volatile organic compounds (VOCs) at the South Shannon well. While the water met drinking standards, the District sought to remove the VOCs. In July 1997, the treatment system began operation and has consistently provided customers in the South Shannon service area with water free of VOCs. The treatment system was upgraded in 2006 and the new system was paid for by the Arizona Department of Environmental Quality (ADEQ). The South Shannon well site is located in the Shannon Road-Rillito Creek superfund site area and ADEQ is responsible for overseeing the cleanup of the groundwater contamination. To date, this effort has focused on determining the source of groundwater contamination. ADEQ has reimbursed the District for operation costs of the treatment system, which have totaled over a million dollars since 2000.