Block Six Water Assn, MO
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (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. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
Who runs the water here
Block Six Water Assn serves about 50 people through 24 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Jefferson County, Missouri. EPA system ID: MO6036207; phone on file: 636-299-2716. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Every lead result on file
That is down 1.9 ppb from 1.9 ppb in the period ending 2022. The highest 90th-percentile result EPA holds for Block Six Water Assn is 14.84 ppb across 6 monitoring periods, none of them over 15 ppb (1 over 10 ppb).
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 1.9 ppb |
| 2022 | 1.9 ppb |
| 2019 | 1.5 ppb |
| 2019 | 1.5 ppb |
| 2019 | 14.84 ppb over 10 |
Against other Missouri systems
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. Block Six Water Assn's reported as 0 (not detected) sits at the 4th percentile in Missouri and the 3rd nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Other water systems in Jefferson County
65 other systems share Jefferson County; 42 of them have a higher latest lead result than Block Six Water Assn. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Jefferson Co Cons Pwsd C 1 | 37,000 | 0 (not detected) |
| Jefferson County Pwsd 1 | 21,113 | 7.25 ppb |
| Jefferson County Pwsd 3 | 17,000 | 0 (not detected) |
| Jefferson County Pwsd 2 | 16,548 | 0 (not detected) |
| Festus Pws | 13,000 | 0 (not detected) |
| Jefferson County Pwsd 10 | 10,000 | 3.86 ppb |
| Jefferson County Pwsd 5 | 8,000 | 1.13 ppb |
| Jefferson County Pwsd 6 | 7,500 | 2.93 ppb |
| Desoto Pws | 6,400 | 1.46 ppb |
| Jefferson County Pwsd 7 | 6,100 | 1.7 ppb |
Your move
Look up your address in Block Six Water Assn's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Block Six Water Assn 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. A zero today does not rule out a jump later - the rules are tightening in 2027.