Downtown Milford residents and business owners need to pour water into every drain in their buildings before the city pumps smoke through sewer lines on Sept. 14.

The Milford Wastewater Department and its contractors will force non-toxic, odorless white and gray smoke through sanitary sewer lines from the Little Miami Brewing Company Event Center on Mill Street to Garfield Avenue, according to a public notice posted on the city's website. The test helps crews spot broken pipes, cracked manholes and illegal stormwater connections underground.

The city posted the notice on Sept. 1 and also announced the testing on Facebook, the Clermont Guardian reported.

The city is asking everyone in the affected stretch to pour one gallon of water into all floor drains, sinks and plumbing fixtures by 8:30 a.m. that day. The water fills plumbing traps and blocks smoke from seeping into buildings.

Skip that step, and smoke could come up through your drains.

What to expect

High-capacity blowers will push the smoke through the sewer system. Residents may see white or gray plumes rising from street manholes or rooftop plumbing vents. That is normal, according to the city's notice.

If smoke does appear inside a building, it signals a faulty or dry plumbing trap. The city asks anyone who sees indoor smoke to open windows and doors immediately, then call the Wastewater Department at 513-831-6982 so crews can log the location.

The smoke is non-toxic, odorless, non-staining and poses no fire hazard, according to the notice.

Who should call ahead

Residents with a known severe respiratory condition should contact the Wastewater Department before testing begins as a precaution. The department can be reached at 513-831-6982.

Why the city tests

Smoke testing helps the city find spots where stormwater or groundwater leaks into the sanitary sewer system. Those leaks can overload the treatment plant and contribute to sewage backups, according to the Clermont Guardian. Milford's Wastewater Department maintains more than 30 miles of sewer mains and eight lift stations across the city.

The full notice is available on the city's website. The city has not announced when results from the Sept. 14 test will be shared or what follow-up work might be planned.