Rancho Nipomo Water Company, CA
Lead detected, under the action levels
Latest 90th-percentile lead: 3.2 ppb (monitoring period 2023-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Rancho Nipomo Water Company at a glance
Rancho Nipomo Water Company serves about 44 people through 36 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in San Luis Obispo County, California. EPA system ID: CA4000771; phone on file: 805-489-0864. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
That is up 3.2 ppb from 0 ppb in the period ending 2022. The highest 90th-percentile result EPA holds for Rancho Nipomo Water Company is 3.2 ppb across 5 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 3.2 ppb |
| 2022 | 0 (not detected) |
| 2021 | 0 (not detected) |
| 2018 | 2.95 ppb |
| 2018 | 0 (not detected) |
Where this result ranks
Of the 2,884 California systems with a lead result, the median latest reading is 0 ppb; 30 are over 15 ppb right now and 215 have gone over at some point. Rancho Nipomo Water Company's 3.2 ppb sits at the 86th percentile in California and the 84th nationally (higher means more lead).
Nearby utilities
71 other systems share San Luis Obispo County; 10 of them have a higher latest lead result than Rancho Nipomo Water Company. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| San Luis Obispo Water Department | 49,534 | 0 (not detected) |
| Atascadero Mutual Water Co | 33,307 | 0 (not detected) |
| City Of Paso Robles Water Division | 31,176 | 0 (not detected) |
| City Of Arroyo Grande Utilities Division | 17,963 | 0 (not detected) |
| California Mens Colony | 15,000 | 0 (not detected) |
| Nipomo Comm Services Dist | 13,771 | 0 (not detected) |
| City Of Grover Beach Public Works Dept | 12,701 | 0 (not detected) |
| Morro Bay Pw Dept - Water Division | 10,757 | 0 (not detected) |
| Templeton Csd | 8,041 | 0 (not detected) |
| Pismo Beach Water Department | 7,944 | 0 (not detected) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Arroyo Grande, CA may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Rancho Nipomo Water Company whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. What a 90th-percentile result does and does not tell you: how to read a lead result. Systems that went over once often dip back under; here is what that means.