What happens when you replace a water heater
Replacing a water heater means removing the old unit and installing a new one in its place. The job takes a plumber or HVAC technician between two and four hours for a straightforward swap, longer if your setup is unusual or the old unit is stuck. You will need to drain the old tank, disconnect the water and gas or electric lines, remove the old heater, set the new one in place, reconnect everything, and test for leaks.
Most homeowners call a licensed plumber to do this work. The cost varies widely depending on whether you have a tank or tankless system, what fuel it uses, and whether your home's plumbing and venting need updates to code. A basic tank water heater replacement typically runs between $1,000 and $2,500 installed, but this varies by region and the specific unit you choose.
Key Takeaways
- Tank water heaters usually last 8 to 12 years; when they leak or stop heating, replacement is normally the only option.
- You will need to choose between a traditional tank, a tankless (on-demand) system, or a heat pump water heater before calling a plumber.
- A licensed plumber handles the drain, disconnect, removal, installation, and reconnection to may support the work meets local code.
- The job takes two to four hours for a standard replacement, but longer if your venting or gas line needs to be rerouted.
- You should get quotes from at least two plumbers before scheduling, because pricing and warranty terms vary significantly.
Choosing between tank, tankless, and heat pump systems
A traditional tank water heater stores 40 to 80 gallons of hot water and keeps it warm all day. It is the cheapest to buy upfront and fits in the same space as your old unit. The downside is that it uses energy continuously, even when nobody is using hot water, and it can run out if you use a lot of hot water quickly.
A tankless (on-demand) water heater heats water only when you turn on a tap. It costs more to buy and install because it often requires upgrades to your gas line or electrical panel, but it uses less energy over time and never runs out of hot water. Installation can take longer if your home's venting or gas supply needs work.
A heat pump water heater pulls heat from the air around it and uses it to warm water, making it the most energy-efficient option. It costs more than a tank but less than a tankless system, and it works best in climates that stay above 50 degrees. It also takes up more space and needs good air circulation around it.
Before you call a plumber, decide which type makes sense for your home, your budget, and how much hot water your household uses. Your plumber can help you understand the trade-offs, but the choice is yours to make first.
Finding and hiring a licensed plumber
Start by asking neighbors, friends, or your real estate agent for plumber recommendations. You can also search online for "licensed plumber near me" or check your city or county's contractor licensing board to verify that a plumber holds a current license.
Call at least two plumbers and describe your situation: the type of water heater you want to replace it with, whether you want to keep it in the same location, and any concerns about your current setup (for example, if the old heater is in a tight space or if your gas line is old). Ask each plumber for a written quote that includes the cost of the new unit, labor, any code upgrades, and what is covered under warranty.
Do not choose based on price alone. A plumber who quotes significantly lower than others may be cutting corners on safety or warranty. Ask whether they are bonded and insured, how long their labor warranty lasts, and whether they handle any follow-up issues if something leaks after installation.
What happens during the replacement visit
The plumber will arrive with the new water heater and tools. First, they turn off the water supply and the gas or electricity to the old unit. They then attach a hose to the drain valve at the bottom of the tank and drain all the water into a floor drain or a bucket (this takes 20 to 30 minutes for a full tank).
Next, they disconnect the water inlet and outlet lines, the gas line or electrical connection, and the vent pipe. Once everything is disconnected, they remove the old heater—this can be heavy and awkward, so most plumbers use a dolly or hand truck. They then position the new heater in the same spot, reconnect the water lines, gas or electricity, and the vent pipe, and turn the water supply back on.
Before leaving, the plumber fills the new tank, bleeds air from the lines, checks for leaks at every connection, and tests that hot water reaches your taps. They will also set the temperature (usually 120 degrees Fahrenheit) and show you where the drain valve and temperature-pressure relief valve are located.
Code upgrades that may be required
Building codes change over time, and your old water heater may have been installed under older rules. When you replace it, your plumber may need to make upgrades to meet current code, even if the old system did not have them.
Common upgrades include installing a pan under the water heater with a drain line that runs to a floor drain (this catches leaks before they damage your home), upgrading the vent pipe if it does not meet current standards, or installing a pressure relief valve if the old one is missing or damaged. Some jurisdictions require a seismic strap to find the heater to the wall in earthquake-prone areas.
Your plumber will tell you which upgrades are required before they start work. These upgrades add to the cost but are necessary to pass inspection and keep your home safe. Ask your plumber whether your city requires a permit and inspection after the new heater is installed—many do, and the plumber usually handles this as part of the job.
How long the new water heater will last
A traditional tank water heater typically lasts 8 to 12 years, depending on water quality, how much hot water your household uses, and whether you flush the tank yearly to remove sediment. A tankless water heater often lasts 15 to 20 years because it does not store water. A heat pump water heater usually lasts 10 to 15 years.
To extend the life of your new heater, have a plumber flush the tank once a year if you have a tank system (this removes mineral buildup that shortens its life). Check the temperature-pressure relief valve yearly by lifting the lever slightly—you should hear a brief hiss of air. If the valve leaks afterward, call a plumber to replace it.
Keep the area around your water heater clear so you can see it if it starts to leak, and know where your water shut-off valve is in case you need to turn off the water quickly. If you notice rust stains on the tank, water pooling underneath, or a sudden drop in hot water, call a plumber—these are signs the heater is failing and may need replacement sooner than expected.
Frequently Asked Questions
Can I replace my water heater myself?
Water heater replacement involves gas or electrical work, plumbing connections, and venting that must meet building code. Most jurisdictions require a licensed plumber to do this work, and your homeowner's insurance may not cover damage caused by DIY installation. Hire a licensed plumber.
What should I do with my old water heater?
Your plumber usually removes the old heater as part of the job and disposes of it. If you are hiring the plumber only for installation, ask a local junk removal service or your city's waste management department how to dispose of it. Some scrap metal recyclers will take it for free because of the metal value.
How long will I be without hot water?
The replacement takes two to four hours, so you will have no hot water during that time. Plan the work for a day when you do not need to shower or do laundry. The plumber will fill the new tank and test it before they leave, so hot water returns the same day.
Do I need a permit to replace my water heater?
Most cities and counties require a permit for water heater replacement. Your plumber usually handles the permit process and arranges for a building inspector to check the work after installation. Ask your plumber whether a permit is needed in your area before they start.
What warranty comes with a new water heater?
Tank water heaters typically come with a 6 to 12 year warranty on the tank and a shorter warranty on parts. Tankless and heat pump systems often have longer warranties. Ask your plumber what the manufacturer's warranty covers and whether they offer an additional labor warranty on their installation work.