Mid-Mark Water Commission, IL
No lead results on file with EPA
Latest 90th-percentile lead: no result on file. The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. EPA's database has no Lead and Copper Rule results for this system. Without them there is nothing to go on, so a tap test is the only way to know.
About Mid-Mark Water Commission
Mid-Mark Water Commission serves about 25 people through 2 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 surface water, in Cook County, Illinois. EPA system ID: IL0310230; phone on file: 708-331-4905. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Other water systems in Cook County
154 other systems share Cook County. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Chicago | 2,721,308 | 6.4 ppb |
| Cicero | 83,000 | 5 ppb |
| Schaumburg | 75,750 | 0.87 ppb |
| Evanston | 74,486 | 6.5 ppb |
| Arlington Heights | 73,320 | 7.6 ppb |
| Palatine | 70,875 | 8.9 ppb |
| Skokie | 66,422 | 9.77 ppb |
| Des Plaines | 60,675 | 5.7 ppb |
| Oak Lawn | 58,362 | 9.3 ppb |
| Orland Park | 58,020 | 0 (not detected) |
What to do in your house
Test your own tap with a certified lab first-draw sample; Markham, IL 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 Mid-Mark Water Commission 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. The action level is dropping - the 10 ppb rule from 2027.