Determine the minimum annular seal depth for a California water well under DWR Combined Well Standards

Steps

1. Identify the well type (Community Water Supply, Industrial, Individual Domestic, Agricultural, Air-Conditioning, or All Other) to find its minimum seal depth under Section 9 of the Combined Well Standards.
2. Apply the general minimum: 20 feet below ground surface for Individual Domestic, Agricultural, Air-Conditioning, and All Other well types; 50 feet for Community Water Supply and Industrial wells.
3. Check whether the shallow-groundwater exception applies: it permits a reduced seal only where the enforcing agency approves and the water to be produced is at a depth less than 20 feet.
4. If the exception applies, seal to no less than 10 feet below land surface and no shorter than 10 feet in length; 10 feet is a floor for an approved exception, not a default minimum.
5. Check the pollution-encroachment provision: wells sited closer to a contamination source than Section 8's separation distances allow require a seal extending to at least 50 feet, with enforcing-agency approval.
6. Verify local county well ordinances, which may impose deeper seal minimums than the state standard.