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Two- to four-family house plumbing for landlords

One building drain, one main shutoff, several households. A guide for owners of two-, three- and four-family houses in Queens, Brooklyn, the Bronx, Staten Island and North Jersey.

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Takes about a minute. Tell us what's happening, what kind of building it is, and the town or neighborhood.

01How the plumbing is usually laid out

Each unit usually has its own kitchen and bathroom lines feeding a shared stack and one building drain to the sewer. Hot water often comes from a separate heater per unit, sometimes from one shared heater or boiler. There is usually one main water shutoff for the whole house.

Drains, traps, vents and cleanoutDiagram D4
  • Cold water
  • Hot water
  • Drain / waste / sewer
  • Vent
Drain-waste-vent basics A sink, a bathtub and a toilet each drain through a trap that holds a water seal against sewer gas. Branch drains slope down to a vertical stack. Vent pipes connect near each trap and rise through the roof so air can enter and the trap seals are not siphoned. A cleanout at the base of the stack gives access for clearing clogs. The building drain carries waste to the sewer. ROOFFLOOR / TO BUILDING DRAIN sink tub toilet cleanout 12345
  1. 1Trap: holds a water seal that blocks sewer gas
  2. 2Branch drain: needs a steady slope toward the stack
  3. 3Stack: carries waste down to the building drain
  4. 4Vents: let air in so draining water doesn't siphon the trap seals
  5. 5Cleanout: access point for clearing a clog

02What landlords usually deal with

  • Clogs caused in one unit that back up in another, often at the lowest unit or basement
  • Water heater failures, often several heaters of the same age
  • Leaks from an upper unit into the one below
  • Frozen pipes, especially in vacant units or exterior kitchen walls
  • Storm-related sewer backups into basement units

03Owner checklist

  1. Label the main shutoff and each unit's heater shutoffs; show tenants where they are
  2. Keep heat on in vacant units in winter
  3. Have the building drain camera-inspected if backups repeat
  4. Plan water heater replacements before they fail
  5. Keep cleanouts accessible
  6. In NYC, use a Licensed Master Plumber; in NJ, a licensed master plumber

04Your obligations as a landlord

Owners of rental units are generally responsible for keeping plumbing in good repair and providing hot water. In NYC, tenants can report conditions to 311. Respond quickly to leak reports: small leaks become ceiling damage downstairs.

05Frequently asked questions

A tenant's clog backed up into another unit. Who pays?

Generally the owner arranges the repair. Whether you can charge a tenant depends on the lease and on proof of misuse.

One heater or one per unit?

Separate heaters simplify billing and outages; one larger system can be more efficient. A plumber can compare for your building.

Sources & review

Last reviewed . General information, not legal or engineering advice. Rules change and individual buildings differ.

  1. NYC Rent Guidelines Board, 2023 Housing Supply Report (NYC HVS 2023)
  2. NYC Dept. of Buildings, Plumbing Permits
  3. NYC DEP, Sewer Backup report

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