Chatham Water Department, MA
Lead detected, under the action levels
Latest 90th-percentile lead: 1.05 ppb (monitoring period 2026-2026). 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 Chatham Water Department
Chatham Water Department serves about 30,000 people through 7,284 service connections, which makes it a large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Barnstable County, Massachusetts. EPA system ID: MA4055000; phone on file: 5089455150. 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 (1.1 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Chatham Water Department is 1.5 ppb across 11 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 1.05 ppb |
| 2025 | 1.1 ppb |
| 2024 | 0 (not detected) |
| 2023 | 0 (not detected) |
| 2023 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2020 | 1.5 ppb |
| 2019 | 1 ppb |
| 2019 | 0 (not detected) |
| 2018 | 1 ppb |
Against other Massachusetts systems
Of the 535 Massachusetts systems with a lead result, the median latest reading is 1.7 ppb; 13 are over 15 ppb right now and 66 have gone over at some point. Chatham Water Department's 1.05 ppb sits at the 35th percentile in Massachusetts and the 56th nationally (higher means more lead).
Neighbouring systems
29 other systems share Barnstable County; 17 of them have a higher latest lead result than Chatham Water Department. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Falmouth Water Dept | 97,551 | 1.1 ppb |
| Dennis Water District | 65,000 | 0 (not detected) |
| Upper Cape Regional Water Cooperative | 56,250 | - |
| Centerville Osterville Marstons Mills Wd | 50,000 | 1.82 ppb |
| Harwich Water Department | 39,144 | 0 (not detected) |
| Yarmouth Water Department | 38,900 | 1.5 ppb |
| Mashpee Water District | 36,922 | 1.4 ppb |
| Hyannis Water System, Town Of Barnstable | 35,000 | 0 (not detected) |
| Brewster Water Department | 35,000 | 3.4 ppb |
| Sandwich Water District | 23,000 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Chatham, MA 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 Chatham 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. The lead result guide covers how utilities pick the homes they sample. Size matters more than most people expect: small vs large water systems.