Waltham Water Department, MA
Lead detected, under the action levels
Latest 90th-percentile lead: 2.24 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 Waltham Water Department
Waltham Water Department serves about 65,218 people through 14,042 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 surface water, in Middlesex County, Massachusetts. EPA system ID: MA3308000; phone on file: 7813143820. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Lead results over time
Against the period ending 2025 (1.92 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Waltham Water Department is 3.83 ppb across 10 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 2.24 ppb |
| 2025 | 1.92 ppb |
| 2024 | 2.17 ppb |
| 2024 | 1.95 ppb |
| 2023 | 3.83 ppb |
| 2023 | 2.45 ppb |
| 2022 | 1.89 ppb |
| 2021 | 1.52 ppb |
| 2021 | 2.35 ppb |
| 2019 | 2.28 ppb |
How Waltham Water Department compares
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. Waltham Water Department's 2.24 ppb sits at the 60th percentile in Massachusetts and the 75th nationally (higher means more lead).
Neighbouring systems
94 other systems share Middlesex County; 36 of them have a higher latest lead result than Waltham Water Department. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Lowell Regional Water Utility | 120,418 | 0 (not detected) |
| Cambridge Water Department | 118,214 | 8 ppb |
| Newton Water Dept. (Mwra) | 88,931 | 1.09 ppb |
| Somerville Water Dept. (Mwra) | 81,045 | 6.62 ppb |
| Framingham Water Dept. (Mwra) | 72,362 | 1.74 ppb |
| Malden Water Division (Mwra) | 66,263 | 9.74 ppb |
| Medford Water Dept. (Mwra) | 61,700 | 8.31 ppb |
| Everett Water Dept. (Mwra) | 49,075 | 1.25 ppb |
| Arlington Water Dept. (Mwra) | 46,308 | 2.68 ppb |
| Billerica Water Works | 42,119 | 2.4 ppb |
Next steps for Waltham, MA
Test your own tap with a certified lab first-draw sample; Waltham, 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 Waltham 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. Size matters more than most people expect: small vs large water systems.