Yonkers: owner lines and a city system with combined sewers
Updated October 30, 2026 · 2-minute read · Old House Sewer Lines
Many Yonkers homeowners are responsible for the sewer line on their own property, according to the city. The Water Bureau page says: "Many Yonkers homeowners are responsible for the repair and maintenance of the water and sewer service lines that run underground on their property, between their homes and the City Water Bureau and Sewer Bureau mains" (City of Yonkers Water Bureau). The page says "many", not all, and cites no section of the city code.
That leaves two practical gaps. The page does not say who answers for the part of a service line outside the property line, and it does not define which owners fall outside "many". A Yonkers owner facing a repair should ask the Sewer Bureau to confirm in writing where the city's responsibility begins at that address. Who owns the sewer line from house to street compares Yonkers with towns that put a definition in their code.
Combined sewers
Parts of Yonkers drain to combined sewers, which carry sewage and storm runoff in the same pipe. The county's 2024 overflow report for the Yonkers Joint plant states: "Combined sewers and unmetered outfalls are owned by City of Yonkers. ... County owns CSO regulators (CSO regulators were built on City of Yonkers combined sewers)" (NYSDEC CSO Annual Report 2024). In that area the city owns, operates and maintains the roads, catch basins and combined collection pipes.
The same report lists 13 combined sewer overflow outfalls, 31 overflow events and 1,888.17 million gallons discharged in 2024. A five-phase overflow control plan was reported as "All phases completed by 1995."
Where the public sewer is combined, the state plumbing code still keeps the house side separate. Section 703.6 says "the sanitary sewer shall be connected independently to the public sewer" (Plumbing Code of New York State). Section 1101.3 bars storm water from sewers intended for sewage only. Why heavy rain pushes water back toward basements is covered in drains that back up in heavy rain.
Where Yonkers sewage goes
The 2026 county tax schedule places Yonkers in five county sewer districts: Bronx Valley No. 1, South Yonkers No. 2, Central Yonkers No. 3, North Yonkers No. 4 and Saw Mill Valley No. 5 (Westchester County tax schedule). The county's Yonkers Joint plant also takes Mount Vernon's sewage and serves a reported population of just over half a million. More is in Westchester's county sewer districts.
Licences and the city's protection-plan pointer
Yonkers has its own licensing rules. The county Department of Consumer Protection notes that contractors working inside Yonkers must be licensed by the city. An archived 2015 version of the city code went further, asking plumbers for a Yonkers competency certificate. Eleven years on, that text may have changed, so ask Yonkers' housing and buildings office what applies before a contract is signed.
The Water Bureau page also says the city partnered in 2017 with a private company that sells optional service-line protection plans to residents. The page describes the arrangement; it does not make the plan mandatory. What to check before buying a protection plan lists the terms worth reading.
Key facts
- Yonkers says "many" homeowners maintain the water and sewer service lines on their property (City of Yonkers).
- The city owns the combined sewers; the county owns the overflow regulators built on them (NYSDEC report).
- 2024: 13 overflow outfalls, 31 events, 1,888.17 million gallons discharged.
- A house sanitary sewer must connect independently to a combined public sewer (§ 703.6, Plumbing Code of New York State).
- The county-owned system feeding the Yonkers Joint plant serves a reported 509,921 people (NYSDEC).