Greenville officials say a routine water test in October 2025 briefly set off alarms at a west-side booster station, flagging total coliform bacteria. Follow-up samples and a focused investigation, they say, found no E. coli and no reason to issue a boil-water advisory, even as the city moved quickly to widen testing and tweak equipment around the site.
What the report found
According to the city's latest consumer confidence report, staff pulled repeat samples after the initial total coliform hit, and those follow-up tests all came back negative for both total coliform and E. coli. Public Services Director David Ducat wrote that total coliform testing is used as an indicator of whether the water might be vulnerable to bacterial contamination, not proof that harmful organisms are present.
Investigators traced the one-off result to equipment at the booster station, including a check valve that had recently been serviced. Crews also removed a ruptured bladder tank and sent it to a lab for analysis. City Manager George Bosanic said the incident reinforced Greenville's monitoring program, and the report notes that sampling in the distribution system was expanded and that a dedicated chlorine feed was added at the booster station, as reported by The Daily News.
How the rules work
Under Michigan's Revised Total Coliform Rule, any repeat sample that tests positive for E. coli triggers a Tier 1 public notice, which typically results in a boil-water advisory within 24 hours. The rule also requires a Level 1 assessment when certain total coliform thresholds are hit, even if E. coli is not found.
Those assessments are designed to sniff out sanitary defects, map out corrective actions, and make sure they are completed on a set timeline. Details on when assessments are required and what they must cover are laid out by Michigan EGLE.
Fixes and state sign-off
While city crews tracked down the source of the anomaly, Greenville installed a dedicated chlorine feed at the west-side booster station and widened its routine sampling plan to keep a closer eye on the system.
State regulators at EGLE reviewed those corrective steps, signed off on them, and identified the booster station as the likely location of the contamination event, according to The Daily News.
Where lead testing stands
The same consumer confidence report also outlines Greenville's lead testing and service line inventory. The city lists a 2023 90th-percentile lead result of 9.2 parts per billion and estimates about 3,400 service lines across town, with 850 confirmed to be free of lead and the rest still under review. The report notes that no sampling sites exceeded the lead action level, according to the City of Greenville.
How that compares to state standards
Michigan lowered its lead action level to 12 parts per billion effective January 1, 2025. Greenville's 2023 90th-percentile result of 9.2 parts per billion sits below that line.
A summary of the state's updated lead and copper rule spells out what happens if a system goes over the action level, including more sampling, public education and planning for service line replacement, as detailed by Michigan EGLE.
What residents should know and where to ask
Because the repeat samples did not show E. coli, city officials say residents do not need to boil their water or change everyday tap-water use in response to the October booster station result.
For customers worried about lead, the report and state guidance recommend flushing cold taps for 30 seconds to two minutes before using water for drinking or cooking, or using an NSF/ANSI-certified filter. More detail is available in the city’s consumer confidence report and state materials.
Questions can be directed to the Public Services Department. City documents list Director David Ducat as the contact at 616-754-5098 and [email protected], per the City of Greenville.
