Tulare County, California: drinking water report. Tulare County in California's San Joaquin Valley has about 473,000 residents, with Visalia and Tulare as…
Tulare County in California's San Joaquin Valley has about 473,000 residents, with Visalia and Tulare as the largest cities. The county is one of the most productive agricultural regions in the world, growing everything from citrus to dairy. Water comes from groundwater wells and surface diversions from the Kaweah and Tule Rivers. Decades of intensive agriculture have fundamentally altered the groundwater quality beneath the valley floor.
Nitrate contamination is severe and widespread in Tulare County. According to the California State Water Resources Control Board's 2024 data, 42 community water systems in the county – more than any other county in California – have documented nitrate MCL exceedances. The sources are fertilizer application and dairy waste from the county's 1,600+ dairies. A 2024 UC Davis Community Water Center report found that small, disadvantaged communities in the county are disproportionately affected, with some systems unable to afford treatment.
The pesticide 1,2,3-trichloropropane (TCP), used historically as a soil fumigant, is another Tulare County groundwater contaminant. California's MCL for TCP is 5 ppt – one of the most stringent standards for any drinking water contaminant – and multiple county water systems have had to install granular activated carbon treatment to comply.
If you are on a small community water system in Tulare County, nitrate should be your first concern. Boiling water does not remove nitrate – it actually concentrates it. For households with infants, this is a health-critical issue because nitrate interferes with oxygen transport in young children.
Check your water for nitrate levels at your address. Reverse osmosis is the most reliable household nitrate removal method. Our water filter guide covers systems certified for agricultural contaminants. Pull your detailed report for local trends, and visit our California page for statewide data.
Drinking water is one exposure route. These federal datasets also cover Tulare County, CA.
The EPA places Tulare County, CA in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
46% of homes in Tulare County, CA were built before 1980, and 10% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Tulare County, CA averages 12.7 µg/m³, above the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide
Across 36 public water systems serving Tulare County, CA with EPA lead testing on record, 3 (8.3%) reported a 90th-percentile lead result above the EPA's 15 ppb action level, and the median is 1.3 ppb. 17 water systems serving Tulare County, CA carry a health-based EPA Safe Drinking Water Act violation.
| Most-cited violation type | Systems affected |
|---|---|
| Lead and Copper Rule Revisions | 8 |
| Total Coliform Rule | 4 |
| Nitrate | 4 |
| 1,2-Dibromo-3-chloropropane (DBCP) | 2 |
| Haloacetic Acids (HAA5) | 2 |
Source: EPA Lead and Copper Rule 90th-percentile tap sampling and EPA SDWIS Safe Drinking Water Act enforcement records, aggregated from the public water systems serving this county. Figures are counts of water systems, not a test of any individual home or tap.