# Apartment Building Repiping in Philadelphia

> Apartment building repiping in Philadelphia: risers and unit branches replaced stack by stack, water-off windows planned with residents, PEX and metallic rules.

URL: https://philadelphiafreedomrepipe.com/multi-unit-repiping/

Supply risers and the branches into each apartment replaced one stack at a time, with water-off windows planned around the people living there and the material the code allows for the building.

Last Updated: October 26, 2026

**14.4%** Share of Philadelphia housing units in buildings with 2 to 4 units, by Census figures

**75 ft** Height of an occupied floor above fire-access level beyond which Philadelphia requires metallic water piping

**$189** L&I alteration permit for the first 7 fixtures in the other-occupancies column; $22.50 for each one after

**R-3** Insulation Philadelphia's EZ standards require on hot water pipe serving more than one dwelling, among other cases

[Philadelphia Freedom Repipe](https://philadelphiafreedomrepipe.com/) repipes small apartment buildings across Philadelphia and nearby Delaware, Montgomery and Bucks County suburbs: rowhouses converted to two or three apartments, purpose-built triplexes and fourplexes, and larger walk-ups. The work replaces the shared risers and the branches into each apartment, planned so that the people living there lose water only for the cutover on their own stack. Licensed and insured contractors carry out the work; inside the city, a Philadelphia licensed master plumber oversees the job and pulls the L&I permit.

Small multi-unit buildings are a large part of the city. By Census figures, 14.4% of Philadelphia’s housing units are in buildings with two to four units, and another 15.1% are in buildings with 20 or more. Many of the small ones are rowhouses split into apartments decades ago, with plumbing added for each new kitchen and bathroom over the years, in whatever material was at hand. The [whole-house repiping](https://philadelphiafreedomrepipe.com/whole-house-repiping/) page covers single-family houses; this page covers what changes when several households share the pipe.

## How water moves through a small apartment building

In a converted rowhouse or a triplex, water enters through the front foundation wall to a meter and main shutoff in the basement, as in a single-family house. From there a basement main feeds one or more risers, the vertical pipes that carry hot and cold water up through the building. Apartments stacked one above another usually share a riser, with each floor’s kitchen or bathroom teed off it. That vertical line of units on a shared riser is what this page calls a stack.

The supply risers are separate from the drain and vent stacks that carry waste down. A supply repipe replaces pressurized water pipe; the drain stacks are a different scope, and the guide to [whether repiping includes drains](https://philadelphiafreedomrepipe.com/guide/does-repiping-include-drains/) shows where that line falls.

Conversions bring their own patterns. A riser run up a closet in 1970 may feed a bathroom that was moved in 1990, through a branch that crosses a ceiling in another apartment. A hot water line from a central heater may run long distances to the top unit. Walking every apartment, not only the basement, is the only way to find those runs, and it is where the plan for openings starts.

## Why risers decide the job

In an old galvanized system, the riser carries the water for every apartment above it, so it is where restriction shows first. When a lower apartment runs a shower, an upstairs one feels it, because a riser narrowed by scale cannot carry both flows. Replacing the branches in one apartment does little if the riser feeding it is still choked; the [galvanized pipe replacement](https://philadelphiafreedomrepipe.com/galvanized-pipe-replacement/) page explains how that scale builds.

The usual plan replaces each riser together with the branches it feeds, one stack at a time. New pipe goes in alongside the old while the old stays in service, and each riser gets a labeled shutoff where it branches into each apartment. That shutoff is one of the practical gains of a multi-unit repipe: a leak in one apartment can be isolated without taking water from the whole building.

Where hot water comes from a central heater, the hot riser and any return line are planned with it. Philadelphia’s EZ permit standards require R-3 insulation on hot water pipe serving more than one dwelling, and at least 4 feet of copper or similar metallic pipe at a water heater’s inlet and outlet, so a PEX system meets each heater through a metal section.

## Staging water-off by stack

Occupied buildings are the normal case, so the schedule is built around the residents. Each stage is defined by stack: which apartments lose water, on which day, for roughly how long. Everything that can happen with the water on, cutting openings, running new pipe, setting valves, happens first. The water goes off only for the cutover, when the new riser is connected and the old one is cut out.

Notice to residents is part of the scope, not an afterthought. Each household should get written notice of the window that affects their apartment, which rooms will be opened, and when someone will need access. Coordinating access to each unit is often the slowest part of the job. The guide to [living through a repipe](https://philadelphiafreedomrepipe.com/guide/living-through-a-repipe/) covers what a water-off day looks like from inside, and the [guide to repiping a rental property in Philadelphia](https://philadelphiafreedomrepipe.com/guide/repiping-rental-property-philadelphia/) covers the owner’s side of planning.

Each stage is pressure tested before its walls close, then flushed after cutover, with aerators cleaned in every apartment on that stack, because scale knocked loose from old valves travels to the first faucet downstream.

## Material rules for apartments

Philadelphia’s plumbing code, amended effective April 1, 2024, allows nonmetallic water piping such as PEX in one- and two-family dwellings and apartments. Section P-605.4 requires metallic pipe in any other occupancy, which matters in a building with a store or office on the ground floor, covered on the [commercial repiping](https://philadelphiafreedomrepipe.com/commercial-repiping/) page. Section P-605.4.1 requires metallic piping where an occupied floor sits more than 75 feet above fire-access level; its exception for nonmetallic pipe inside individual units applies to new construction between 75 and 150 feet, not to a repipe of an existing building.

For most two- to four-unit buildings, both [PEX repiping](https://philadelphiafreedomrepipe.com/pex-repiping/) and [copper repiping](https://philadelphiafreedomrepipe.com/copper-repiping/) are allowed, and the choice turns on routes, fittings and the people living there. PEX can be fished through closed plaster cavities with fewer openings, which counts for more when every opening is in someone’s home. Copper is rigid and metallic, and some owners prefer it for exposed basement mains. Flexible water connectors are allowed in apartments only where they stay accessible. The guide to [whether PEX is allowed in Philadelphia](https://philadelphiafreedomrepipe.com/guide/is-pex-allowed-in-philadelphia/) covers the rule in full.

## Permit, connections and what moves the price

A repipe in a building with four or fewer dwellings and up to four stories can usually go through L&I’s EZ permit without plans. Plan on one permit for each building, filed for that building’s own scope, and a licensed master plumber overseeing it. A two-unit conversion falls in L&I’s one- and two-family column, $50 for the first 7 fixtures and $22.50 for each one after; a building with three or more apartments falls in the other-occupancies column, $189 for the first 7 fixtures and $22.50 after. The [Philadelphia repipe permit guide](https://philadelphiafreedomrepipe.com/guide/philadelphia-repipe-permit/) covers the filing.

Each building on a street with a main also needs its own connection to it. A common pipe is allowed only on the same deeded property, after the meter, and not under a building, so a rear building fed through the front one is worth checking before the plan is set. If the service line itself is lead or galvanized, PWD’s HELP loan covers service line work in residential buildings of up to four units; the [lead service line replacement](https://philadelphiafreedomrepipe.com/lead-service-line-replacement/) page explains it.

No reliable published range exists for multi-unit repiping, because buildings differ too much. The drivers are clear:

| Driver | Why it moves the price |
| --- | --- |
| Number of apartments and stacks | Each stack is a stage with its own openings, cutover and test |
| Fixture count | Every kitchen, bathroom and laundry connection is a branch; it also sets the permit fee past 7 fixtures |
| Central or per-unit water heaters | Central heat means a long hot riser, insulation and possibly a return line |
| Plaster, tile and finished units | Openings in occupied apartments take more care to make and close |
| Access to each unit | Scheduling entry to every apartment sets the pace |
| Mixed-use ground floor | Metallic pipe for the commercial space and the other-occupancy permit column |

## Related resources

- [Rowhouse repiping](https://philadelphiafreedomrepipe.com/rowhouse-repiping/) for single-family attached houses
- [Repiping plaster walls](https://philadelphiafreedomrepipe.com/guide/repiping-plaster-walls/), and how openings are planned and closed
- [Partial repiping](https://philadelphiafreedomrepipe.com/partial-repiping/) when one stack is the problem
- [Main water shutoff replacement](https://philadelphiafreedomrepipe.com/main-water-shutoff-replacement/) for the valve every apartment depends on

## What's included

- A walk-through of every unit, the basement main, each riser and each apartment's branches
- A stack-by-stack plan that says which units lose water, when and for how long
- Risers replaced with a labeled shutoff at the branch into each apartment
- Branches to each kitchen, bathroom and laundry connection in the scope
- Water heater connections, central or per unit, with the metallic section the code requires
- Insulation on shared hot water lines where the EZ standards require it
- The L&I permit for the building, pulled by a licensed master plumber, and its inspections
- A pressure test of each stage before walls close, and a written list of openings by unit

## How the repipe plan changes with the size of the building

|  | Two-unit conversion | Three- or four-unit building | Larger apartment building |
| --- | --- | --- | --- |
| Typical layout | A rowhouse split into a first-floor and an upper apartment, often on one riser | One apartment per floor, or two side by side, on two or more stacks | Several stacks with central risers and longer horizontal mains |
| Pipe material | PEX or copper | PEX or copper; apartments may use nonmetallic pipe | Metallic where an occupied floor is more than 75 ft above fire-access level |
| L&I fee column | One- and two-family: $50 for the first 7 fixtures | Other occupancies: $189 for the first 7 fixtures; L&I confirms the line | Other occupancies, and plans may be needed |
| Water-off planning | Two households, one cutover | One stack at a time, residents above and below affected together | Stack by stack over several days or weeks |
| Typical cost | No published range; priced from the scope | No published range; priced from the scope | No published range; priced from the scope |

## Guides for this work

- Decision Guide [When Should You Repipe a Rental Property in Philadelphia?](https://philadelphiafreedomrepipe.com/guide/repiping-rental-property-philadelphia/)For owners of rented houses and small apartment buildings: how to decide when old pipe should go, why vacancy is the easiest window, how to repipe one stack at a time with people living there, and what the owner has to handle on a lead service line.
- Learn [Is PEX Allowed in Philadelphia?](https://philadelphiafreedomrepipe.com/guide/is-pex-allowed-in-philadelphia/)What the Philadelphia Plumbing Code says about PEX water pipe: where it is allowed, where metal is required, the rules at the water heater and the fittings, the pending code bill, and how the suburbs differ.
- Learn [Do You Need a Permit to Repipe a House in Philadelphia?](https://philadelphiafreedomrepipe.com/guide/philadelphia-repipe-permit/)How the L&I plumbing permit works for a repipe in Philadelphia: when one is needed, who can apply, what the EZ permit covers, the published fee lines and surcharges, and what happens at inspection.
- Learn [How Long Does a Repipe Take When You Are Living in the House?](https://philadelphiafreedomrepipe.com/guide/living-through-a-repipe/)The schedule depends on floors, fixtures, access and the plaster, not on a standard number of days. How the work is staged so the water is off only at cutovers, and what to get ready before the first day.
- Learn [How Do You Repipe a House With Plaster Walls?](https://philadelphiafreedomrepipe.com/guide/repiping-plaster-walls/)Plaster on lath can be opened and closed cleanly if the openings are planned. Where the cuts go, how routing keeps them few, the three levels of patching, and what keeps the dust in one room.

## 

1. First call You describe the house: rowhouse, twin or detached, how many floors and bathrooms, what the pipe looks like where you can see it, and what made you call. That sets up the walk-through.
2. Assessment The walk-through starts at the meter and main shutoff, traces the pipe up every floor, checks pressure and flow, and maps the routes and the openings. You get a written scope that says what is replaced and what stays.
3. The work A licensed master plumber pulls the L&I permit. New lines go in while the old ones keep the house running, then each section is cut over during a planned water-off window.
4. Completion The new piping is pressure tested and inspected, then flushed. Shutoffs are labeled, openings are closed to the finish the quote names, and you get a list of anything old that stayed in service.

## What this work looks like

A kitchen sink cabinet wall opened to the studs showing copper lines to angle stops and supply lines to the faucet

Copper risers dropping from a basement main, each with a brass shutoff valve and a tag

A bathroom wall opened beside a pedestal sink showing red and blue PEX lines to shutoff valves

New copper mains along the joists of a converted building's brick basement, branching to several risers

## Multi-unit repiping questions

### When does a Philadelphia apartment building need metallic water pipe?

Less often than many owners expect. Philadelphia's code allows nonmetallic water piping such as PEX in one- and two-family dwellings and apartments. Two limits apply: metallic piping is required where an occupied floor is more than 75 feet above fire-access level, and any commercial space in the building needs metallic pipe for the piping that serves or runs through it.

### How do residents keep water during a multi-unit repipe?

The work is staged by stack. New risers and branches are installed alongside the old pipe while it stays in service, and only the cutover takes water off, for the units on that stack. Each resident gets written notice of the window that affects their apartment. The number and length of windows depend on the building and are set in the plan.

### Do the risers have to be replaced at the same time as the apartment branches?

Not always, but the risers usually decide the job. A new branch tied into a corroded galvanized riser still gets the riser's restriction and its rust. Replacing a riser and the branches on that stack in the same stage means one round of openings and one cutover for those units, instead of two.

### Which L&I permit fee column applies to a three- or four-unit building?

L&I's fee summary has a lower column for one- and two-family dwellings and a higher column for other occupancies. A building with three or more apartments falls outside the first, so the other-occupancies figures, $189 for the first 7 fixtures and $22.50 for each one after, are the ones to expect. L&I confirms the line item on the application.

### Can two buildings on one Philadelphia lot share a water line?

Only within narrow limits. Philadelphia's code requires each building on a street with a public main to have its own connection to it. A common pipe is allowed only on the same deeded property, after the meter, and not under a building. A rear carriage house fed through the front building's basement is one to check before planning a repipe.

## Related services

### Whole-house repiping

Every hot and cold supply line from the main shutoff to the fixtures, replaced in the material the Philadelphia code allows for the building and pressure tested before the walls close.

### PEX repiping

Flexible PEX supply lines run through a house's own walls and joists, in the occupancies where Philadelphia's code allows plastic water pipe, with metal where the code requires it.

### Copper repiping

Rigid copper supply lines for mixed-use buildings and other occupancies where Philadelphia requires metal, and for houses whose owners choose it, joined by press or solder with care around old framing.