Knorrwood Knolls Subdivision, MI
Exceeded the action level in the past
Latest 90th-percentile lead: 2.7 ppb (monitoring period 2023-2023). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest result is under the action level, but this system has gone over 15 ppb before. Lead comes from pipes, not the source water, so a home with a lead service line can still be exposed. Test your own tap.
Who runs the water here
Knorrwood Knolls Subdivision serves about 240 people through 75 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 Oakland County, Michigan. EPA system ID: MI0003666; phone on file: 248-452-2271. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
That is down 19.3 ppb from 22 ppb in the period ending 2017. The highest 90th-percentile result EPA holds for Knorrwood Knolls Subdivision is 22 ppb across 2 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2023 | 2.7 ppb |
| 2017 | 22 ppb over 15 |
Against other Michigan systems
Of the 1,227 Michigan systems with a lead result, the median latest reading is 1 ppb; 31 are over 15 ppb right now and 109 have gone over at some point. Knorrwood Knolls Subdivision's 2.7 ppb sits at the 72nd percentile in Michigan and the 79th nationally (higher means more lead).
Other water systems in Oakland County
105 other systems share Oakland County; 29 of them have a higher latest lead result than Knorrwood Knolls Subdivision. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Troy | 85,854 | 0 (not detected) |
| Rochester Hills | 74,000 | 1.3 ppb |
| Waterford Township | 73,441 | 1 ppb |
| Southfield | 71,739 | 0 (not detected) |
| Pontiac | 63,776 | 1.6 ppb |
| Royal Oak, City Of | 57,236 | 4 ppb |
| Farmington Hills, City Of | 56,984 | 0 (not detected) |
| Novi, City Of | 56,780 | 0 (not detected) |
| West Bloomfield Township | 49,479 | 0 (not detected) |
| Bloomfield Township | 41,691 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Waterford, MI 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 Knorrwood Knolls Subdivision 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. More in what a past exceedance means today.