While sewers were once directly monitored way back, leading to fun maps about the various smells in NYC, things are a lot more advanced these days. Last year, the NYC Department of Environmental Protection installed 21 monitors throughout its sewer system in Queens to detect problems with the flow before it can cause sewage to back up onto streets—or worse yet, into residents’ homes. This issue is even more critical in New York City because of our combined sewer system, which mixes wastewater and stormwater. The DEP is now hoping to expand this program for a total of 64 sewage monitors not just in Queens, but throughout the city.

Since the implementation of the first monitoring devices last year, the DEP has resolved more than 100 issues that could have resulted in a surcharge or overflow. In addition, the system will also allow crews to prevent serious damage from elevated floodwaters in communities near bodies of water. The monitors are just one component of a larger effort to increase proactive maintenance of New York’s sewer system, and the program’s expansion not only means that the city will respond faster to sewage issues, but it will enable the DEP to better plan future sewer infrastructure projects.

Read about what Manhattan sewers smelled like in 1910 and sewage treatment in New York City. Read more from our Cities 101 series about how stuff works in the city.