Water Heater Replacement Cost in 2026: Real Price Ranges

What you pay for a water heater replacement depends on the size, fuel type, venting, and the code extras that show up on the invoice. The table below gives installed ranges for standard tank units in the St. Louis area for 2026. These are ranges, not quotes. A simple swap in an open basement with existing utilities sits at the low end. A tight closet with a failed pan, no expansion tank, and a gas line that needs resizing sits at the high end.

Standard tank installed ranges

Power-vent units use a blower to exhaust gas. They cost more because the unit has a fan and the venting is different. If your old unit was power-vent, you cannot swap in an atmospheric unit without checking the venting and clearance. That is a code issue, not a preference.

The extras that show up on invoices

These are the line items that turn a “$1,200 special” into a $2,000 bill. They are not scams by themselves. They are code requirements and real labor.

• Expansion tank: $150–$350 installed. Required in many areas when there is a backflow preventer or closed system. It absorbs thermal expansion. Without it, the T&P valve can drip or the tank can fail early.
• Pan and drain: $100–$250. A pan with a drain line protects the floor and finished space. Some codes require it in attics or above living space.
• Permit: $75–$250. A legitimate permit means an inspection. A quote that skips it is cheaper for a reason.
• Disposal: $50–$150. Hauling the old tank out is labor and a dump fee.
• Gas line upgrade: $300–$1,200. A larger BTU unit or a longer run may need a bigger line. A tankless retrofit often needs 3/4-inch or larger.
• Electrical upgrade: $500–$2,500. A new circuit, a disconnect, or a panel upgrade for an electric tankless.
• Weekend or emergency premium: $150–$500. After-hours calls cost more. A tank leaking on a Sunday is not the time to shop.
• Code corrections: $100–$500. Old shutoff valves, missing drip legs, improper venting, or no sediment trap on the gas line.

A suspiciously cheap quote usually leaves out the permit, the expansion tank, the pan, disposal, and code corrections. It may also use a shorter warranty or a builder-grade unit with a six-year tank instead of a ten-year. Ask for the model number and the warranty terms. A $900 quote that becomes $1,800 after the “extras” is not a deal. A $1,600 quote that includes the permit and the expansion tank is often the cheaper job.

DIY reality check

In many places, a homeowner can legally replace their own water heater. That does not make it a good idea for most people. You are combining gas, water, and electrical in one job. You need to shut off the gas, drain the tank, disconnect the old unit, set the new one, connect the gas with the right pipe dope and a sediment trap, solder or press the water lines, wire the electric element if it is electric, fill the tank before turning the power back on, and check for leaks. If you miss a step, you can flood the basement, create a gas leak, or burn out an element in seconds.

If you buy the unit yourself and hire a pro to install it, labor alone runs $400 to $900 for a standard swap. Many plumbing companies refuse to install customer-supplied units. It is not just attitude. They cannot warrant the unit, they do not know how it was stored, and if it fails, they get blamed. Some will install with a labor-only warranty. Ask before you buy.

STOP: If you smell gas, do not touch the thermostat or any electrical switch. Leave the house and call your gas utility from outside. Do not try to tighten a gas fitting with the valve open.

STOP: Shut off the breaker before touching any electrical connection on an electric water heater. Mains voltage can kill you. Do not turn the power back on until the tank is full of water. A dry element burns out immediately and can crack the tank.

STOP: A leaking tank or a failed T&P valve can release water at 150°F or hotter. Do not stand in front of the discharge pipe. Scalding water can cause third-degree burns in seconds.