This indicator is an index score combining information about 13 contaminants and 2 types of water quality violations found during drinking water sample testing.  This index was developed by the California Environmental Protection Agency (CalEPA) and is included in the CalEnviroScreen (CES).

Everyone should have access to safe, affordable drinking water. Water is an essential human right needed for healthy outcomes. While most drinking water in California meets federal and state health and safety standards, some drinking water is contaminated by bacteria and chemicals. Contamination can occur from natural or human sources. Natural sources of contamination may include soil, rocks and fires. For example, arsenic, which is known to cause cancer, is naturally present in some rocks and soils and can lead to groundwater contamination.¹²¹ Human sources of contamination can include sewage, factories and runoff from farms. Nitrates from fertilizer or animal manure can contaminate groundwater and wells. Nitrates can cause birth defects, miscarriages and a blood condition in infants called blue baby syndrome (methemoglobinemia).¹²¹ Lead can enter drinking water when service pipes containing lead age. Housing built before 1986 is more likely to have lead pipes, fixtures and solders. Even low levels of lead exposure are not safe for children, babies or soon-to-be-born babies. Lead is linked to premature birth, central and peripheral nervous system damage, learning disabilities, impaired growth, anemia and hearing problems.¹²²

Drinking water standards are called Maximum Contaminant Levels (MCLs). Title 22 of the California Code of Regulations details MCLs standards for the state. There are two basic types of MCLs standards. Primary MCLs address health concerns. Secondary MCLs include issues of aesthetics, or appearance, which include taste and odor and can affect consumer intake and confidence. The State Water Resources Control Board website maintains up-to-date information on water related laws and regulated contaminants.

Exposure to contaminated drinking water disproportionately impacts low-income communities, communities of color, and people in rural areas of the state.^{123, 124} Within these communities, there is also a demonstrated mistrust of drinking water, even when the water supplies meet health standards.¹²⁵ Moreover, even when water meetings safe drinking standards, it may not meet aesthetic standards including taste and odor. According to Prevention Institute’s Water Health and Equity Case Statement, the 2015 American Housing Survey found that one in five households in the Los Angeles-Long Beach Metro Area reported their water is not safe to drink, almost three times the national average. Additionally, they noted that one in three Hispanic households and one in four Black households reported unsafe drinking water, compared to one in nine Non-Hispanic White households.¹²⁵ More renters (25%) than homeowners (14%) reported unsafe drinking water, and nearly twice as many households earning less than $50,000 per year reported unsafe drinking water compared to households earning more than $50,000 annually.¹²⁵

Distrust of the drinking water supply can impact how people access and use water. Low-income communities and families of color often buy bottled water instead of using tap water, especially when tap water is discolored or has an odor.^{126, 126, 128} A Pacific Institute study found that Latino families spend on average 4% of their income buying bottled water.¹²⁹ For many families, buying bottled water reduces the money available to purchase or secure other necessities. This is particularly concerning since the water standards for bottled water are overseen by the U.S. Federal Drug Administration and are less strict that those set by U.S. Environmental Protection Agency for tap water supplies. In addition, when there is a mistrust of water supplies, sugar sweetened beverages m ay be substituted for water.¹³⁰ Sugar sweetened beverages are associated with obesity and type 2 diabetes.^{131, 132}

Our water system is very complex and for many, knowledge of water infrastructure is limited to what flows from the faucet. It may take some time assess the water landscape in your community. Questions to consider: Where does your water come from and are there publicly available water testing reports? Does available data indicate that drinking water is meeting health and safety levels? How is drinking water safety perceived, especially among low-income communities and communities of color? What agencies, providers, community organizations and local coalitions are dedicated to water issues in your area? For more information, contact your local water district and the California Department of Water Resources Integrated Regional Water Management Program.

Communities can work to Reduce Water Contamination from water sources themselves, as well as stormwater runoff or industry-related contaminants that ends up in the drinking water supply. To negate possible contamination from infrastructure, communities should comply with state and federal water laws, remove lead pipes, and address premise plumbing infrastructure issues. To create more water resilient communities, jurisdictions should take steps to prevent stormwater runoff by focusing on prevention efforts that preserve and maintain water quality, including water resource, drought-resistant native plants, and climate resilience actions. To prevent contamination from agriculture, pharmaceuticals or oil and gas industries, jurisdictions should ensure inspections, provide economic incentives, and address various sources of contamination. Another essential strategy is Improving Water Quality Data, Monitoring and Reporting by the local water agencies, as well as proper disclosure to community members of water contamination issues and offering resources for consumers and water purveyors alike. Local governments should also Improve Water Infrastructure to prevent contamination and may want to explore creating dedicated funding streams to pay for infrastructure improvements. These improvements should prioritize areas that have lacked safe drinking water in the past or present. They should also be context-sensitive to areas with small water systems and domestic wells that are more decentralized and more difficult to monitor. Finally, all communities should strive to Build an Equitable Water Future by advancing plans, policies and systems changes that promote water as a basic human right and ensure equitable access to safe, affordable drinking water for everyone.