Western Hills Water District/Diablo Gran, CA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2025-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
About Western Hills Water District/Diablo Gran
Western Hills Water District/Diablo Gran serves about 2,000 people through 596 service connections, which makes it a small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Stanislaus County, California. EPA system ID: CA5010039; phone on file: 408-828-7007. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Western Hills Water District/Diablo Gran's lead record
Against the period ending 2024 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Western Hills Water District/Diablo Gran is 0 ppb across 9 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2024 | 0 (not detected) |
| 2023 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2021 | 0 (not detected) |
| 2020 | 0 (not detected) |
| 2019 | 0 (not detected) |
| 2017 | 0 (not detected) |
| 2016 | 0 (not detected) |
Against other California systems
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. Western Hills Water District/Diablo Gran's reported as 0 (not detected) sits at the 46th percentile in California and the 31st nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Neighbouring systems
59 other systems share Stanislaus County; 15 of them have a higher latest lead result than Western Hills Water District/Diablo Gran. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Modesto, City Of | 218,915 | 12 ppb |
| Turlock, City Of | 72,888 | 0.97 ppb |
| Ceres, City Of | 54,513 | 0 (not detected) |
| Riverbank, City Of | 25,625 | 21 ppb |
| Patterson, City Of | 24,977 | 0 (not detected) |
| Oakdale, City Of | 23,235 | 0 (not detected) |
| City Of Modesto - Salida | 14,576 | 0 (not detected) |
| City Of Newman-Water Department | 12,389 | 0 (not detected) |
| City Of Waterford | 8,788 | 0 (not detected) |
| Hughson, City Of | 7,977 | 0 (not detected) |
Your move
Look up your address in Western Hills Water District/Diablo Gran's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Western Hills Water District/Diablo Gran 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. The lead result guide covers how utilities pick the homes they sample. Small systems behave differently: why small systems go over more often.