Water Heater · Service

Water heater replacement, decided before it fails

Which type actually suits your house, what the inspector will add to the bill, and how to avoid buying whatever unit happens to be on the truck. Free matching with vetted local installers.

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In short

What is water heater replacement?

Replacing a water heater is two decisions, not one. First, what type replaces it — a storage tank on the same fuel, a tankless unit, or a heat pump water heater — which is decided by your fuel supply, the space, and how your household actually draws hot water. Second, what the replacement drags along with it: a permit, an expansion tank, updated venting or a modern relief-valve discharge, because a replacement is inspected against today's code and not the code your old unit was installed under. Getting the first decision right is worth more than shopping the second.

Triggers

Signs you need water heater replacement

Rusty or metallic-tasting hot water that runs clear on the cold side — the tank lining is failing, and lining failure is terminal
Water pooling under the tank rather than dripping from a fitting above it
You are running out of hot water noticeably sooner than you used to, with no change in household size
The unit is old enough that you cannot find the data plate, or the installer sticker is from a company that no longer exists
A rumbling or popping noise on every heating cycle that a flush no longer quiets — hardened sediment sitting on the burner surface
You have already paid for one repair this year and a second part has now failed
You are remodelling, converting a garage, or adding a bathroom, and the existing unit was already at its limit
You are selling, and an unpermitted or visibly corroded heater is going to come up in the inspection report anyway

Seeing something not on this list? Browse water heater problems by symptom →

The job

How water heater replacement actually works

Decide the type before you shop the unit

The four realistic routes are a gas storage tank, an electric storage tank, a tankless unit, or a heat pump water heater. What decides it is not efficiency marketing — it is what fuel reaches the space, how much air and headroom the space has, whether there is a drain nearby, and how long you plan to stay in the house. Each route has a dedicated page here that will talk you out of it if it does not fit.

Watch for: Being routed to a type because it is what the installer stocks. Ask directly: "which of the four did you rule out for my house, and why?" An installer who has considered and rejected the other three is giving you a decision. One who only ever proposes one is giving you their inventory.
Size it to how your household actually draws hot water

Storage tanks are sized by first hour rating — how much hot water the unit can deliver in the busiest hour, which combines stored volume with how fast it reheats. Tankless units are sized instead by flow rate at your required temperature rise, because they never store anything and must heat water as it passes. These are different units of measurement answering different questions, and a tank capacity figure tells you nothing useful about a tankless unit.

Watch for: Sizing by "same as what you had". The old unit may have been undersized for years and everybody adapted around it, or oversized because a previous owner had a larger family. Describe your actual worst-case hour — the morning where showers, the dishwasher and the laundry overlap — and let the installer work back from that.
Site survey: space, clearances, drainage and access

Somebody should look at where the unit lives before quoting. Attic and upper-floor installations need a plumbed drain pan because a failure there does not stay there. Garage installs have their own restrictions in many jurisdictions. Tight interior closets rule some types out entirely. And the old unit has to physically get out — narrow basement stairs and tight mechanical rooms genuinely change what can be installed.

Watch for: A quote given entirely over the phone from a model number. It will be re-quoted on install day, and the second number is the one you pay.
Permit and the code items it triggers

In most US jurisdictions water heater replacement is permitted, inspected work. The permit is what forces the items your old installation may not have: thermal expansion control, a correctly terminated relief valve discharge, seismic restraint in some regions, drain pans, and compliant venting or combustion air. Requirements vary by city and state — the local building department is the authority, not a national blog.

Watch for: A cash discount for skipping the permit. It shifts every code liability onto you, voids some manufacturer warranties, and reliably surfaces during a home sale. It is also the single clearest signal about how the rest of the job will be done.
Shut down, drain and remove the old unit

The fuel or power is isolated and the old unit is drained down before it moves — a full storage tank is far too heavy to handle safely, and draining a tank full of hardened sediment can take much longer than expected. Connections are cut back to a clean point rather than reused blindly.

Watch for: Old shut-off valves and supply connections being reused because they still look fine. A valve that has not been turned in a decade often will not seal again once it has been moved, and the time to find that out is while the installer is still standing there.
Set, connect and bring the installation up to current code

The new unit is set level, connected to water, connected to its fuel or circuit, vented if it needs venting, fitted with any required expansion tank and pan, and given a relief valve discharge that terminates where a discharge is allowed to terminate. This is also the point where a fuel or type change ripples outward, because a different unit style rarely reuses the previous vent, circuit or gas run unchanged.

Watch for: A relief valve discharge that ends somewhere convenient rather than somewhere compliant — pointed at the ceiling, threaded down to a reduced size, or terminated inside a closed cabinet. It is a safety device, and it is the most commonly botched item on an otherwise tidy install.
Fill, purge, test and set the temperature

The unit is filled with the air purged from the lines before any heat is applied, then fired or energised, checked for leaks at every joint, and set to a delivery temperature. On gas units the combustion and draft get verified. You should be shown the shut-off, the relief valve, and how to isolate the unit in a hurry.

Watch for: Being handed a running unit with no walkthrough. Knowing where your water and fuel shut-offs are is worth more, on the day something goes wrong, than any feature on the unit.
Disposal, permit close-out and warranty registration

Haul-away of the old unit is normally included but is worth confirming in writing, since a drained tank left in a garage becomes your problem. The permit needs to be signed off by the inspector, not merely pulled. And most manufacturers require registration within a set window, plus proof of professional installation, before the warranty is worth anything.

Watch for: A permit that was pulled but never closed. Ask for the final inspection sign-off, not the permit number — an open permit is a live issue at resale.

Money

What does water heater replacement cost?

Most replacements land roughly between $1,500 and $6,000 installed, with heat pump and tankless retrofits typically at the upper end. The gap between two quotes is usually the code items — permit, expansion tank, venting, electrical — rather than the appliance. See the cost guide for a full breakdown.

See the full water heater replacement cost guide — by material, size and region →

Straight answer

When water heater replacement is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

The leak is at a fitting, not the tank. Water tracking down the outside of a tank often starts at the cold inlet, the relief valve or a union above it. A leak from the tank shell itself is unrepairable; a leak from a fitting above it is a cheap fix. Have somebody establish which one you have before you buy an appliance.
The only symptom is lukewarm water on an electric unit. One failed heating element produces exactly that, and an element is one of the cheapest parts in the house. Replacing a whole tank because the upper element died is a genuinely common and expensive mistake.
The unit is still under warranty on the tank. Long tank warranties are the reason to check the data plate date before agreeing to anything. A covered replacement tank changes the maths entirely, even though you still pay labour.
You are mid-remodel and the layout is not settled. Where the heater lives affects framing, venting, drainage and circuit runs. Decide the position in the plan, not twice — once now and once when the bathroom moves.
It failed at 9pm and nothing is actively flooding. An after-hours emergency replacement narrows your choice to whatever is on the truck and adds a premium for the privilege. If the water is off and the damage is contained, one business day of waiting usually buys you both a better unit and a better price.
You want a heat pump water heater but the space cannot host one. They need air volume, a condensate drain and tolerance for noise. Wanting the efficiency is not enough — check the requirements before you commit, because the retrofit to make the space suitable can cost more than the saving.

Your options

Types of water heater replacement

Gas storage tank

The like-for-like route where gas already serves the space. Venting and combustion air decide whether it is simple or not.

Electric storage tank

The simplest swap, and often the only option in a condo or an interior closet with no vent path.

Tankless

Endless hot water, but the retrofit — gas line, venting, electrical — is where the money goes.

Heat pump water heater

The efficiency play, with real requirements: space, air volume, a drain, and tolerance for the noise.

Compare water heater options side by side →

Before you sign

What to check when hiring for water heater replacement

Which of the four types did you rule out for my house, and on what grounds?

This is the question that separates an installer from an order-taker. The reasoning tells you whether they surveyed your space or read your model number.
What first hour rating are you sizing to, and what did you assume about my usage?

For a storage tank this is the number that decides whether you run out of hot water. If the answer is a gallon capacity with no usage assumption behind it, the sizing is a guess.
Which code items will the inspector require here, and are they in this quote?

Expansion tank, pan, discharge piping, restraint, venting. This is where two quotes for the same appliance diverge by four figures — and where the cheaper one usually catches up later.
Who pulls the permit, and will you give me the closed inspection?

Pulling a permit and closing it are different events. An open permit shows up when you sell, and by then the installer is long gone.
Is haul-away and disposal of the old unit included?

Usually yes, occasionally not. A drained tank left in your garage is heavy, awkward, and not something most waste services will take.
What is warranted by the manufacturer, what by you, and for how long?

Tank, parts and labour are almost always three different periods. The labour warranty is the one that decides whether year three costs you anything.
If you open this up and find something unexpected, how is that priced?

Corroded shut-offs, a vent that cannot be reused, a circuit that is undersized. Agree the change-order mechanism before the old unit is on its side, not after.

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Local pros

Water Heater Replacement near you

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Related work

Often done at the same time

Water Heater Repair

Before you commit to replacing

Tankless Installation

What the retrofit really involves

Expansion Tank Installation

The code item most people meet first here

Water Heater Maintenance

Making the new one last

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FAQ

Water Heater Replacement — questions people ask

Still have a question? Talk to our team →

Should I replace my water heater with the same type I have now?

Often, but not automatically. A like-for-like swap is the fastest and usually the cheapest route, because the fuel, venting and circuit are all already there. It is worth pausing when something has changed — you have added a bathroom, the household has grown or shrunk, the unit sits somewhere that floods, or your fuel costs have shifted. The moment of replacement is the only cheap moment to change type, because the labour is happening anyway.

What size water heater do I need?

For a storage tank, size by first hour rating rather than by gallons alone — it accounts for both what the tank holds and how quickly it reheats, so a smaller tank with fast recovery can outperform a larger slow one. For a tankless unit, capacity is a flow rate at a given temperature rise, which depends on how cold your incoming water is. Describe your worst overlapping hour to the installer and ask them to show their working.

Do I need a permit to replace a water heater?

In most US jurisdictions, yes, and the inspection that comes with it is what enforces expansion control, relief valve discharge, venting and restraint. Rules vary by city and state, so your local building department is the only authority worth trusting on this. Unpermitted water heater work is one of the more commonly flagged items in a pre-sale inspection.

How long does a water heater replacement take?

A straightforward like-for-like tank swap is usually a half day. It grows when the type changes — a tankless retrofit or a first heat pump water heater in a space that was not built for one can run a full day or longer once gas, venting, electrical or condensate work is involved. Access matters too: a tight basement stairwell can add hours by itself.

Can I supply my own water heater and just pay for installation?

Some installers will, many will not, and it changes the warranty picture. When the installer supplies the unit, one party owns both the appliance and the workmanship, and a failure is their problem to sort out. When you supply it, you own any manufacturing defect and the labour to swap it. Ask how they handle a warranty claim in each case before deciding the saving is real.

Is it worth repairing an old water heater instead of replacing it?

It depends entirely on which part failed. Thermostats, elements, thermocouples and relief valves are inexpensive and worth doing on a unit with life left. A tank that is leaking through its shell is not repairable at any price, because the lining has gone and welding or patching a lined tank is not a repair. Our repair page walks the repair-versus-replace line in more detail.