Index Water Dept, WA
Lead detected, under the action levels
Latest 90th-percentile lead: 6.6 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.
Who runs the water here
Index Water Dept serves about 420 people through 129 service connections, which makes it a very small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Snohomish County, Washington. EPA system ID: WA5335600. Ask the utility on your bill for your address in their service line inventory.
Every lead result on file
That is up 4.7 ppb from 1.9 ppb in the period ending 2021. The highest 90th-percentile result EPA holds for Index Water Dept is 6.6 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 6.6 ppb |
| 2021 | 1.9 ppb |
| 2018 | 2.5 ppb |
How Index Water Dept compares
Of the 2,218 Washington systems with a lead result, the median latest reading is 1 ppb; 18 are over 15 ppb right now and 62 have gone over at some point. Index Water Dept's 6.6 ppb sits at the 94th percentile in Washington and the 94th nationally (higher means more lead).
Other water systems in Snohomish County
117 other systems share Snohomish County; 3 of them have a higher latest lead result than Index Water Dept. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Alderwood Water District | 245,715 | - |
| Everett Public Works Dept. City Of | 215,774 | 3.5 ppb |
| Marysville Utilities | 88,582 | 2 ppb |
| Lynnwood City Of | 68,204 | - |
| Sno Pud 1 - Lake Stevens | 67,710 | 3.2 ppb |
| Silver Lake Water & Sewer District | 65,033 | - |
| Edmonds City Of | 34,065 | - |
| Mukilteo Water & Wastewater Distr | 31,437 | - |
| Arlington City Of | 29,508 | 0 (not detected) |
| Mountlake Terrace City Of | 26,402 | - |
Next steps for Index, WA
Test your own tap with a certified lab first-draw sample; Index, WA 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 Index Water Dept 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.