It has built and upgraded wastewater treatment plants, and is spending about $1.5 billion just on green projects such as installing “curbside rain gardens” and other infrastructure in parks, playgrounds and public housing projects to absorb storm water and keep it out of the sewer system. It also plans to disinfect some sewer overflows before they are discharged from sewer lines by using a chlorination process in the pipes.

In total, the city has 14 wastewater treatment plants that process an average of 1.3 billion gallons of sewage on rainless days. They can generally handle up to 3 billion gallons per day.

The new campaign aims to reduce the combined sewer overflows into Newtown Creek, a 3.5-mile-long waterway that forms part of the border between Brooklyn and Queens; and Bowery Bay, and Flushing Bay and Flushing Creek in northern Queens.

To sign up volunteers, the city will run ads on Facebook, partner with local environmental groups, and mail fliers to about 30,000 homes in two dozen neighborhoods that lie in the drainage areas for those waterways, including Williamsburg, Greenpoint, Astoria, Steinway, Jackson Heights, Elmhurst, and Corona. The campaign will focus on those living in single-family homes because their water usage data will be easier to collect and analyze, according to city officials who hope to eventually expand it to apartment buildings too.

One recruitment pitch compares the overflows to a familiar problem: “It’s like rush hour on the freeway: there’s only so much road and if everyone uses it at the same time, it can get jammed. And just like rush hour, the best thing to do is avoid it.”

City officials will monitor real-time rainfall data at the Newtown Creek and Bowery Bay treatment plants to determine when combined sewer overflows are likely. Once gauges at the plants register a half-inch of rainfall, volunteers will be sent a text message asking them to wait to use water. After the storm ends, and plant operations return to normal, they will receive a second text thanking them.