In Philadelphia, replacing a water heater is plumbing work that needs a permit from the Department of Licenses and Inspections (L&I), and a licensed master plumber has to oversee it. For a straight swap the permit can usually be issued right away when the contractor applies, and when the job is done the master plumber signs a certification that the installation meets the Philadelphia Plumbing Code. Before you call, decide whether you want the same kind of heater or something different (tankless, heat pump, or a combi boiler that heats the house and the water), because that choice changes the venting, the electrical work, the space you need and the rebates you can get.
This is general information. For permit questions in the city, L&I has the final word; in Bucks, Montgomery and Delaware counties, ask your township or borough.
Signs it's time to replace, not repair
Water heaters wear out on a fairly predictable schedule. A Department of Energy Building America guide puts tank-type heaters at 10 to 15 years and tankless units at up to 20 years. The manufacture date is usually printed on the rating label or coded into the serial number.
Replacement is usually the right call when:
- The tank itself leaks. Water pooling under the tank, or rust and moisture on the bottom seam, means the steel tank is failing. A tank can't be patched.
- Hot water comes out rusty from the hot side only, which points to corrosion inside the tank.
- The heater is near or past its expected life and needs an expensive part.
- You keep running out of hot water after a change in the household, and the tank is simply too small.
Some problems are repairs, not replacements: a leaking drain valve or fitting, a faulty thermostat or heating element on an electric unit, or a gas burner that won't stay lit. A plumber can tell you which you have. Rumbling and popping usually come from sediment on the bottom of the tank; flushing can help, but on an old tank it's often a sign of age.
If it's leaking right now
- Shut the cold-water valve on the pipe going into the top of the heater. If you can't find it or it won't turn, close the main shutoff near the water meter.
- For a gas heater, turn the gas control to "off" or "pilot". For an electric one, switch off its breaker at the panel.
- Call a plumber. If you smell gas, leave the house and call PGW (or PECO in the suburbs) from outside.
What the City requires
L&I's plumbing permit page says a licensed master plumber must oversee plumbing work, and that the master plumber needs an active license, current City taxes and insurance on file with L&I. The page lists only a few kinds of work that don't need a permit (minor repairs with the same material such as faucets, valves and parts, resetting a toilet without changing pipes, and stopping leaks or clearing stoppages). A new water heater isn't one of them.
For a replacement, L&I says the permit "may be issued immediately" when the contractor applies. As of October 2026 the page lists a water heater replacement fee of $31 for one- and two-family homes, a $100 nonrefundable filing fee that counts toward the permit fee, and small City and state surcharges. Fees change, so treat these as a guide and check the page.
When the work is finished, the master plumber completes L&I's Water Heater Replacement Certification Form. It records the size, make, model and fuel, whether the heater vents into a chimney (gravity) or through the wall (direct vent), whether a thermal expansion tank and a drain pan are required and installed, and certifies compliance with the plumbing code. The form says the contractor must give it to the owner and upload it to the permit. Ask for your copy and keep it with the house papers; it's useful when you sell or when an insurer asks.
In practice: if a quote doesn't mention the permit, ask. A plumber who offers to skip it is telling you something about how they work.
Your options in a Philadelphia house
Same type, same spot
The simplest and usually the quickest job is a like-for-like swap: a gas tank for a gas tank, electric for electric, in the same place. Most Philadelphia rowhomes and twins have the heater in the basement next to the furnace or boiler, and the existing gas line, water lines and venting can often be reused after the plumber checks them.
The venting is the part worth asking about. Many older gas tanks vent into the brick chimney. If your furnace or boiler was replaced with a high-efficiency unit that vents through the wall, the water heater may be the only thing left using that chimney, and it may need a liner. Our chimney inspection guide explains this "orphaned water heater" problem.
Tankless
A tankless (on-demand) gas heater hangs on the wall and frees up floor space in a tight basement. The same DOE guide notes that a gas tankless unit's fuel demand may require a larger gas line from the meter or a dedicated supply line, and that its electronic controls don't work during a power outage. It also vents with its own pipes, needs power, and benefits from periodic descaling where water is hard. Ask the plumber whether your gas meter and piping can supply it and where the vent will exit, since rowhome side walls are often close to a neighbor's windows.
Combi boiler
If you have a gas boiler that's also near the end of its life, a combination boiler heats both the radiators and your tap water in one wall-hung unit. It's a heating job as much as a plumbing one, so get the boiler side reviewed by someone who knows hot-water and steam systems. Our radiator troubleshooting guide covers what kind of system you likely have.
Heat pump water heater
A heat pump water heater is an electric tank that pulls heat from the surrounding air. ENERGY STAR recommends installing them in interior spaces that stay between 40°F and 90°F all year with about 1,000 cubic feet of air around the unit, and notes they cool the space they're in and run less efficiently in cold rooms. A roomy basement often qualifies; a small closet or a crawl space under a rear addition often doesn't. In humid Philadelphia summers the cooling and dehumidifying is a bonus. They also need a drain for condensate and usually a dedicated electrical circuit, so switching from gas means electrical work as well.
Rebates and tax credits
- PGW customers (Philadelphia): PGW's EnergySense residential rebates, listed for September 2024 through August 2027 while funds last, include rebates for ENERGY STAR tankless water heaters and high-efficiency combi boilers on its qualified product list, with higher amounts for customers in PGW's Customer Responsibility Program or who received a LIHEAP or hardship grant. Separately, PGW's efficiency page lists a bill credit for switching from an electric or oil water heater to a qualifying gas one. Check the current amounts and the paperwork (invoice with model and serial numbers, a signed application) before you buy.
- PECO customers in the suburbs: rebates change by program year, so check PECO's Ways to Save for your home page for what's available now.
- Federal tax credit: the energy efficient home improvement credit that used to cover heat pump water heaters ended for equipment placed in service after December 31, 2025, according to the IRS. Don't count on it for a 2026 installation.
What drives the price
We don't publish a single number, because two water heater jobs on the same block can differ a lot. What moves the price:
- the type and capacity of the new heater;
- whether it's a like-for-like swap or a change of fuel or type (new gas line, new circuit, new venting);
- venting work, including a chimney liner;
- code items the old installation lacked, such as an expansion tank, a drain pan or a proper relief valve discharge pipe;
- access: steep, narrow basement stairs and tight utility rooms are common in rowhomes;
- removal and disposal of the old tank;
- the permit, and whether it's an emergency call.
Checklist before you hire
- Find the old heater's label: fuel, gallons and the age if you can work it out.
- Take photos of the heater, the pipes on top, the vent connection and the space around it.
- Decide whether you want a like-for-like swap or are open to tankless, a heat pump or a combi boiler.
- Note how many people live in the house and whether you run out of hot water now.
- Confirm the plumber is a licensed master plumber (or works under one) and will pull the L&I permit.
- Ask for a written quote that names the model, the permit, disposal of the old tank and any code upgrades.
- Check rebate eligibility with PGW or PECO before you buy, not after.
- Keep the invoice and the signed certification form.
For the general hiring checks, including Pennsylvania Home Improvement Contractor registration, see how to check a contractor in Philadelphia.
When to call a pro
In Philadelphia, a water heater replacement always involves one. Gas connections, venting and the relief valve are safety items, and the City requires a master plumber to oversee the work and certify it. Call right away if the tank is leaking, you smell gas, the relief valve is discharging, or there's soot or scorching around the burner or vent.
If you're ready to get quotes, you can post your plumbing project on HomeKept. Describe the job once, with the photos and details from the checklist above, and compare up to 3 estimates from local pros. It's free for homeowners.
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