Knollwood, MO
Lead detected, under the action levels
Latest 90th-percentile lead: 1.4 ppb (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. 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 Knollwood
Knollwood serves about 87 people through 33 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Harrison County, Missouri. EPA system ID: MS0240027; phone on file: 314-736-4743. 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 2017 (1.7 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Knollwood is 1.7 ppb across 2 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2023 | 1.4 ppb |
| 2017 | 1.7 ppb |
Where this result ranks
Of the 1,674 Missouri systems with a lead result, the median latest reading is 1.04 ppb; 2 are over 15 ppb right now and 74 have gone over at some point. Knollwood's 1.4 ppb sits at the 58th percentile in Missouri and the 62nd nationally (higher means more lead).
Nearby utilities
14 other systems share Harrison County; 5 of them have a higher latest lead result than Knollwood. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Harrison County Pwsd 2 | 3,740 | 1.34 ppb |
| Bethany Pws | 3,292 | 1.72 ppb |
| Woolmarket Village Estates | 2,910 | 1 ppb |
| Robinwood Forest Utility Inc | 1,275 | 0 (not detected) |
| Lakewood Environmental | 982 | 7 ppb |
| Harrison County Pwsd 1 | 823 | 0 (not detected) |
| Palmer Creek Utility Assc, Inc | 570 | 0.3 ppb |
| Deerwood Utilities | 404 | 0.7 ppb |
| Pass Christian Isles | 399 | 4 ppb |
| Gilman City Pws | 380 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Des Peres, MO 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 Knollwood 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. Systems that went over once often dip back under; here is what that means.