Thomas, OK
Lead detected, under the action levels
Latest 90th-percentile lead: 2.5 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.
Thomas at a glance
Thomas serves about 1,238 people through 646 service connections, which makes it a small system under EPA's size classes. It is privately owned and draws groundwater, in Custer County, Oklahoma. EPA system ID: OK2002001; phone on file: 580-661-1400. They can tell you what your service line is made of and whether they pay to replace it.
Lead results over time
That is down 3.4 ppb from 5.9 ppb in the period ending 2022. The highest 90th-percentile result EPA holds for Thomas is 5.9 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 2.5 ppb |
| 2022 | 5.9 ppb |
| 2019 | 1.53 ppb |
| 2016 | 0 (not detected) |
Where this result ranks
Of the 870 Oklahoma systems with a lead result, the median latest reading is 0.81 ppb; 6 are over 15 ppb right now and 66 have gone over at some point. Thomas's 2.5 ppb sits at the 80th percentile in Oklahoma and the 78th nationally (higher means more lead).
Neighbouring systems
10 other systems share Custer County; 1 of them has a higher latest lead result than Thomas. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Weatherford | 10,833 | 0 (not detected) |
| Clinton | 8,883 | 1.5 ppb |
| Custer County Rwd #3 | 960 | 0 (not detected) |
| Arapaho | 748 | 0 (not detected) |
| Frontier Development Auth | 437 | 0 (not detected) |
| Custer City Pws | 393 | 6.5 ppb |
| Butler | 345 | 0 (not detected) |
| Country East Mhp | 97 | 0.9 ppb |
| Shady Acres Custer County | 40 | 0 (not detected) |
| Foss Reservoir Mcd | 12 | 0 (not detected) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Thomas, OK 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 Thomas 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. Why sampled homes are the worst-case ones is in the guide to reading the number. The action level is dropping - the 10 ppb rule from 2027.