Winterthur, DE
Above the new 10 ppb level coming in 2027
Latest 90th-percentile lead: 12 ppb (monitoring period 2022-2024). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Under the current 15 ppb rule this is not an exceedance, but it is above the 10 ppb action level that takes over in Nov 2027. Test your own tap; filter if your result shows lead.
Who runs the water here
Winterthur serves about 687 people through 39 service connections, which makes it a small system under EPA's size classes. It is privately owned and draws groundwater, in New Castle County, Delaware. EPA system ID: DE0000503; phone on file: 302-888-4954. They can tell you what your service line is made of and whether they pay to replace it.
Lead results over time
That is up 12 ppb from 0 ppb in the period ending 2021. The highest 90th-percentile result EPA holds for Winterthur is 12 ppb across 3 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2024 | 12 ppb over 10 |
| 2021 | 0 (not detected) |
| 2018 | 1.4 ppb |
Where this result ranks
Of the 196 Delaware systems with a lead result, the median latest reading is 0.31 ppb; 1 are over 15 ppb right now and 14 have gone over at some point. Winterthur's 12 ppb sits at the 98th percentile in Delaware and the 98th nationally (higher means more lead).
Neighbouring systems
30 other systems share New Castle County; 1 of them has a higher latest lead result than Winterthur. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Artesian Water Company | 231,114 | 1 ppb |
| Wilmington Water Department | 107,976 | 0 (not detected) |
| Veolia Water Delaware, Inc | 100,495 | 2 ppb |
| Newark Water Department | 40,000 | 1 ppb |
| Middletown Water Department | 17,700 | 0 (not detected) |
| Municipal Services Commission | 5,549 | 0 (not detected) |
| East Ncc District | 5,538 | 0 (not detected) |
| North West Pump District | 4,149 | 0.8 ppb |
| Willow Grove Mill | 3,090 | 0 (not detected) |
| Delaware City Water Department (Awc) | 2,610 | 1 ppb |
Your move
Test your own tap with a certified lab first-draw sample; Winterthur, DE 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 Winterthur 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. See what changes at 10 ppb in 2027.