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Removing a house trap under New York's plumbing code

Updated October 30, 2026 · 2-minute read · Old House Sewer Lines

Yes, an old house trap can be removed in New York, and no new one may go in. The state plumbing code, at §1002.6, says building (house) traps "shall be prohibited." Removal is an alteration, so a licensed plumber must bring the new piping up to the code for new work. The step most often overlooked is the cleanout the trap used to provide.

The ban is not new. The NYS Department of State says building traps were first prohibited in new homes under the 2003 Residential Code, with local exceptions, and that those exceptions ended with the 2016 code update (NYS DOS). The same wording appears in both the 2020 code and the 2025 edition, which has been in force since December 31, 2025 (NYS DOS).

Why the code dropped the trap

A building trap is a fitting in the building drain that stops air moving between the house plumbing and the building sewer (NYS DOS). DOS calls it redundant, because each sink, tub and toilet already has its own water-seal trap, and says it "can potentially result in a blocked or clogged pipe." In older southern Westchester basements that U-shaped fitting, often called a running trap, is a familiar choke point; how a house trap works and why house traps clog cover it in detail.

DOS also states two limits that matter to owners. A municipality cannot require building traps in building drains. A homeowner who wants to add one needs a variance. Existing traps may stay where they are unless the plumbing is altered.

What removal involves

The trap often doubles as the only cleanout for the horizontal drain and for the junction where the building drain turns into the building sewer, 30 inches of pipe past the outside wall by the residential code definition. DOS says its removal "might require new cleanout(s)" and that any alteration must conform to the code for new work. Under §708.1.3, that junction needs a cleanout at the junction or within 10 feet of developed length upstream of it, and §708.1.2 calls for cleanouts at intervals of no more than 100 feet on building sewers smaller than 8 inches (PCNYS chapter 7). Sewer cleanouts explains what those access points do.

The vent beside the trap, the so-called fresh-air inlet, also comes into play. DOS calls the "fresh air intake" name inaccurate because any vent moves air both ways and can release sewer gas, which is why such vents must be kept away from windows and other openings. What happens to that pipe is a decision for the plumber and the building department; see the fresh-air inlet.

In Westchester, plumbing work that needs a plumbing permit must be done by a plumber holding a Westchester County licence, which the county says is valid in every city, town and village (Westchester County). Yonkers keeps separate plumbing rules; owners there should confirm requirements with Yonkers. Ask the village or city building department which permit applies before work starts.

Key facts

  • New building (house) traps are banned by §1002.6 of the state plumbing code, 2020 and 2025 editions alike (ICC).
  • A town or village cannot require a building trap, and a homeowner needs a variance to add one (NYS DOS).
  • Removing a trap may require new cleanouts, and the altered piping must meet the code for new work (NYS DOS).
  • The drain-to-sewer junction needs a cleanout at the junction or within 10 feet upstream (§708.1.3) (ICC).
  • Plumbing work that needs a permit in Westchester must be done by a county-licensed plumber (Westchester County).

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