Domestic Wells and State Small Water Systems

Domestic Wells

The owner of a domestic well often provides groundwater to just themselves, or up to four total service connections. More groundwater information (English / Spanish). 

State and local agencies do not regulate water quality for domestic wells, nor do they require water quality monitoring of the wells.1 As of 2021 though, counties are required to support domestic wells in planning for drought and water shortages since the last two drought periods left thousands of domestic well users without water. More drought planning and management information (English / Spanish).

  • Domestic well construction, alteration, and destruction is regulated locally by the County Environmental Health Department. A local permit is required for well construction and usually required for alteration and destruction. Groundwater Sustainability Agencies and local water agencies may also have requirements for domestic wells. Find and contact the local permitting agency in your area to get more information: Permitting Agencies.

    To learn more about well construction, visit page 9 in A Guide for Private Domestic Well Owners. To learn more about well destruction, visit page 13 in A Guide for Private Domestic Well Owners. If you stop using a well, it is best to hire a contractor to properly “destroy” the well to prevent groundwater contamination that can result from an abandoned well.

  • Despite the fact that domestic well owners are not legally required to test the water in their well for contaminants, it is important to do so anyway to understand if the drinking water is safe.

    You can use the Community Water Center’s Drinking Water Tool or the State Water Board’s Groundwater Information System to learn if your area may have contamination. These resources generally inform the public where contamination is likely to occur, but does not cover all the areas with unsafe drinking water.

    The best way to know if your water is safe is by testing it. See the resources below:

  • If you or your water users experience any of the following, stop using the well water:

    • negative health impacts that may be linked to drinking the water;

    • the water smells, looks, or tastes strange;

    • water testing shows high contaminant levels.

    See your options for immediate responses and long term solutions to address unsafe drinking water: Water System Failures and Solutions.

Know More: Initially, the Department of Water Resources (DWR) was the only group (state agency or otherwise) with the most information about domestic wells throughout CA. Yet, DWR’s website does not come close to accurately portraying how many domestic wells in California are contaminated.2 There is no consistent or strict testing for wells, like those that supply water to State Smalls. This means that contamination of those wells is not properly recorded and oftentimes, the dangerous water quality is only found out when consumers start getting sick or smell/taste bad water.

State Small Water Systems

State Small Water Systems (State Smalls) supply drinking water to 5-14 service connections and about 25 people, for more than 60 days in a year.3 A State Small usually relies on drinking water wells to pull up groundwater. More groundwater information (English / Español). 

As of 2021, counties are required to support State Smalls using domestic wells in planning for drought and water shortages. This is because the last two drought periods in California left thousands of domestic well users without water. More drought planning and management information (English / Español).

  • Step 1: Get an Operating Permit

    To create a State Small, you first need to get an operating permit from your county’s environmental health division in-person or online.4

    Examples:

    Step 2: Get a Drinking Water Source

    There may already be wells available to supply drinking water. If not, a State Small then must get a permit from the County in order to drill a well to access groundwater. After the well is planned, the well driller must send the Department of Water Resources information about the potential well, including how deep the well will be drilled and what the soil conditions are that they will be drilling through.5

  • State Smalls are subject to fewer regulatory requirements than Public Water Systems, which are larger systems over 15 service connections.6 There is no main state agency that oversees State Smalls to make sure they are monitoring the quality of their drinking water or managing the amount of harmful contaminants in that water.

    Instead, a local health officer – usually the county environmental health agency or the Local Primacy Agency – grants local State Smalls their operating permit and keeps records on them, like results of water testing.7 More about Local Primacy Agencies (English / Español). The county then sends these records to the State Water Board, which is trying to collect more information about State Smalls’ drinking water quality to better understand drinking water concerns throughout the state.8

  • While a Public Water System is required to monitor all regulated primary and secondary contaminants, a State Small only has to monitor some primary contaminants (contaminants that cause bad health effects) and secondary contaminants (contaminants that impact taste, smell, or look of the water). More information on Public Water Systems: Public Water System. More info on primary and secondary contaminants: Maximum Contaminant Levels.

    Required Water Testing: In terms of primary contaminants, a State Small only has to test their water supplies for contaminants like arsenic, lead and copper, nitrate, and perchlorate.9 And in terms of secondary contaminants, a State Small only has to monitor fluoride, iron, manganese, chlorides, and total dissolved solids.10 Each water source only has to be tested one time for these contaminants.11 (For example, if the State Small tested its groundwater source in 2002, it does not have to test that source again in the future.) Coliform (bacteria like E.coli) must be tested quarterly and reported to the County. A State Small may only do this level of testing after the well begins to operate.

    See the resources below to understand contamination in the area and how to test the water:

    When Additional Testing Is Required: The State Small has to continually disinfect the water before it reaches consumers12 and test that source quarterly for bacteria (total coliform bacteria).13All results must be sent to the local health officer.14If the test comes back positive – meaning that there is harmful bacteria in the water source – the State Small must test again within 48 hours.15 If this second test also comes back positive, the State Small must check that same second sample for E.coli and notify the local health office or county.16

    If a State Small is using a groundwater source that the local health office designated as vulnerable to contamination, the State Small has to additionally test that water supply for organic contaminants considered “volatile organic compounds” or VOCs.17 VOCs include contaminants like benzene,18 MTBE,19 perchloroethylene/tetrachloroethylene (PCE),20 and trichloroethylene (TCE).21 Each vulnerable water source only has to be tested once for VOCs.22

    Local health officers might require a State Small to do additional testing of water sources based on the one test of the above-mentioned contaminants but are not required to do so.

  • If you or your water users experience any of the following, stop using the well water:

    • negative health impacts that may be linked to drinking the water;

    • the water smells, looks, or tastes strange;

    • water testing shows high contaminant levels.

    See your options for immediate responses and long term solutions to address unsafe drinking water: Water System Failures and Solutions.

This Page Last Updated: May 13, 2024