Gswc - Claremont, CA
Lead detected, under the action levels
Latest 90th-percentile lead: 5.6 ppb (monitoring period 2024-2026). 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.
About Gswc - Claremont
Gswc - Claremont serves about 39,776 people through 11,431 service connections, which makes it a large system under EPA's size classes. It is privately owned and draws surface water, in Los Angeles County, California. EPA system ID: CA1910024; phone on file: 760-515-8322. They can tell you what your service line is made of and whether they pay to replace it.
Lead results over time
Against the period ending 2025 (5.7 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Gswc - Claremont is 5.7 ppb across 6 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 5.6 ppb |
| 2025 | 5.7 ppb |
| 2025 | 3.6 ppb |
| 2023 | 0 (not detected) |
| 2020 | 3.3 ppb |
| 2017 | 1.7 ppb |
How Gswc - Claremont compares
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. Gswc - Claremont's 5.6 ppb sits at the 93rd percentile in California and the 92nd nationally (higher means more lead).
Neighbouring systems
197 other systems share Los Angeles County; 5 of them have a higher latest lead result than Gswc - Claremont. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Los Angeles-City, Dept. Of Water & Power | 3,875,566 | 3.9 ppb |
| Long Beach Utilities Department | 466,772 | 0.97 ppb |
| Santa Clarita Valley Water Agency | 292,014 | 0 (not detected) |
| Gswc - Southwest | 277,740 | 1.7 ppb |
| San Gabriel Valley Water Co.-El Monte | 240,000 | 0 (not detected) |
| Los Angeles Cwwd 40 Reg 4 & 34 Lancaster | 208,129 | 1.8 ppb |
| Glendale-City, Water Dept. | 192,212 | 5.3 ppb |
| Suburban Water Systems-San Jose | 170,523 | 0 (not detected) |
| Pasadena Water And Power | 165,448 | 1.9 ppb |
| Pomona - City, Water Dept. | 151,713 | 2.1 ppb |
Your move
Test your own tap with a certified lab first-draw sample; San Dimas, 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 Gswc - Claremont 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.