Wilmington Water Department, DE
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2021-2023). 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.
Who runs the water here
Wilmington Water Department serves about 107,976 people through 37,915 service connections, which makes it a very large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in New Castle County, Delaware. EPA system ID: DE0000663; phone on file: 302-576-3017. They can tell you what your service line is made of and whether they pay to replace it.
Every lead result on file
That is down 2.2 ppb from 2.2 ppb in the period ending 2020. The highest 90th-percentile result EPA holds for Wilmington Water Department is 5.6 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2023 | 0 (not detected) |
| 2020 | 2.2 ppb |
| 2017 | 5.6 ppb |
Against other Delaware systems
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. Wilmington Water Department's reported as 0 (not detected) sits at the 48th percentile in Delaware and the 40th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Other water systems in New Castle County
30 other systems share New Castle County; 17 of them have a higher latest lead result than Wilmington Water Department. 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 |
| 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 |
| Delaware Correctional Center | 2,000 | 0 (not detected) |
Your move
Look up your address in Wilmington Water Department'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 Wilmington Water Department 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. A zero today does not rule out a jump later - the rules are tightening in 2027.