New York's 2025 plumbing code: the sewer rules homeowners notice

The New York State plumbing code rules for a building sewer are in the 2025 edition of the state code (PCNYS), in force since December 31, 2025. It bans new house traps, requires backwater valves below street level and sets cleanout spacing and minimum slope.

The 2025 Uniform Code, including the plumbing code, was adopted July 25, 2025, with an amended rule adopted December 5, 2025 (NYS DOS, Notice of Adoption). Between adoption and the effective date, builders could follow either the 2020 or the 2025 code. The 2025 edition says it includes material from the 2024 International Plumbing Code. It applies across Westchester; New York City has its own code, and none of the towns this site covers are in the city.

The rules most owners meet

The sections below read the same in the 2020 and 2025 editions, according to the state's published texts (2025 PCNYS; 2020 PCNYS).

House traps draw the most questions in older southern Westchester houses. The state Department of State says the trap is redundant because each fixture has its own water seal, and that it can potentially lead to a blocked pipe (NYS DOS, Building Traps). Existing traps may stay, but adding a new one takes a variance, and a town cannot demand one. Removing a trap during alterations may mean adding cleanouts, since the trap is sometimes the only one. See the house trap.

The backwater valve rule turns on elevation, not age. If a basement toilet or drain sits below the rim of the next upstream manhole cover on the public sewer, the code wants a valve fitted where that fixture's waste leaves the house, either on the building drain itself or on its own branch line. Details are in when a backwater valve is required.

Cleanouts follow fixed spacing. Sewers 8 inches and larger need manholes instead, the first within 200 feet of the building drain. A turn sharper than 45 degrees needs a cleanout, though one can serve several turns within 40 feet. See the sewer cleanout.

Pipe, slope and repairs

Table 702.3 lists approved building sewer materials, including ABS, cast iron, copper, PVC, polypropylene, stainless steel and vitrified clay; the 2025 table adds newer polyethylene entries. Slope is 1/4 inch per foot for pipe 2½ inches or smaller and 1/16 inch per foot for 8 inches and up, as covered in sewer line slope and depth.

When an existing building's whole sanitary system is replaced, any old building sewer that will be reused must be examined internally for slope, breaks, obstructions and size (§ 703.4). Each building on a lot facing a street with a public sewer needs its own connection, though several buildings on one lot may share a building sewer (§ 701.3).

In the 2020 edition, § 716 limits pipe bursting to gravity sewers 6 inches and smaller, replaced at the same size with HDPE pipe of SDR 17 to ASTM F714, with video before and after (NYSPC 2020, Chapter 7). Water softener discharge must end through an air gap (§ 608.4), covered in softener drain lines.

Background

Building traps were first barred from new houses in the 2003 Residential Code of New York State, with local exceptions allowed. The 2016 code update ended those exceptions.

Key facts

• New York's current plumbing code is the 2025 PCNYS, effective since the last day of 2025 (NYS DOS).
• New house traps are prohibited under § 1002.6; existing ones may remain unless the plumbing is altered (NYS DOS).
• § 714.1 ties the backwater valve duty to elevation: a basement fixture sitting lower than the street manhole upstream must be protected.
• A cleanout is required within 10 feet of the drain-to-sewer junction, then no more than 100 feet apart (§ 708.1).
• Minimum slope for 3- to 6-inch pipe is 1/8 inch per foot (Table 704.1).
• Reused sewers in a full re-pipe must be examined internally (§ 703.4).

Sources

• NYS DOS — Uniform Code adoption notice
• NYS DOS — 2025 PCNYS text
• NYS DOS — 2020 PCNYS text
• NYS DOS — Code Outreach: Building Traps
• ICC — 2020 PCNYS Chapter 7, Sanitary Drainage