The cost of replacing a 50 gallon water heater depends on four things. Is the new unit gas or electric? Can the venting and gas line be reused? How easy is the old tank to remove? Is a permit or a code upgrade needed? The tank itself is only one line of the quote.
A like-for-like swap in an accessible basement is the simplest job. A move from electric to gas, a heater in a tight closet or a failed vent can add time and parts, and we explain each item before work starts.
This guide explains what drives the price, how to pick a size, how to tell your tank is failing and what the local water quality means for the life of a new heater.
Signs your 50 gallon tank is failing
The signs that matter
- Water pooling under the tank or rust streaks on the tank body.
- Rusty or cloudy hot water that does not clear after running.
- Popping or rumbling noises as sediment boils at the bottom.
- Less hot water than before, or a heater that runs constantly.
- A tank that is old and has never been flushed.
A leak from the tank body cannot be repaired. If the leak is at a fitting or a valve, a repair may be worthwhile, and our water heater repair crews can tell the difference in a few minutes.
What drives the replacement price
We do not publish a total because every house is different. These are the five factors we price.
Fuel type
Gas units need venting, a gas line and combustion air. Electric units need a circuit sized for the elements.
Venting and gas line
Reusing a sound vent is simpler than rebuilding one. A gas line that is too small or corroded adds work.
Access and removal
A tank in an open basement is easier than one in a tight closet or attic. Stairs and distance matter.
Code upgrades
Expansion tanks, a drain pan, new shutoff valves and a proper discharge pipe may be required or advised.
Permit and timing
A permit may apply, and a weekday install costs less than an after-hours emergency swap.
Ask which of these your quote includes. A quote that leaves out the venting or the permit step can change after the work begins.
Gas or electric: a quick comparison
| Question | Gas 50 gallon | Electric 50 gallon |
|---|---|---|
| Needs venting | Yes, a flue to the outdoors | No vent needed |
| Needs a gas line | Yes | No |
| Electrical needs | A small outlet for controls on some models | A dedicated circuit for the heating elements |
| Common concern | Combustion air and flue condition | Element and thermostat life |
| Best for | Homes that already have a gas line and vent | Homes without gas or with limited space |
Switching fuel is possible but adds work. If you are weighing a tankless or a heat pump heater instead, our water heater installation page covers the options.
Is 50 gallons the right size?
Fifty gallons works for many households of three to five people, but the first-hour rating on the label matters more than the tank size. That rating tells you how much hot water the unit can deliver in the first hour of heavy use.
If your family runs two showers and a dishwasher at the same time, a higher recovery rate or a larger tank may fit better. If your house has fewer people than it used to, a smaller tank saves on standby loss. A plumber can match the size to the way you actually use hot water.
Maryland Heights local note: your water and your tank
Missouri American Water's 2021 water quality report for its St. Louis County system lists lime softening as part of its treatment and chloramine as the disinfectant. Total hardness at its Missouri River plants ranged from 76 to 170 ppm as calcium carbonate, which is about 4.4 to 9.9 grains per gallon, and its Meramec plant ranged from 66 to 148 ppm.
Moderately hard water leaves scale and sediment in a tank over time, so a periodic flush and a check of the anode rod matter. Hardness varies by street and season, so test your tap or ask your utility for its current annual report before you decide whether a softener is worth adding.
Source: Missouri American Water, 2021 water quality report for its St. Louis County system (water utility).
What happens during the swap
Shut off and drain
We shut off the fuel or power and the cold supply, then drain enough of the old tank to disconnect it safely.
Remove the old tank
The old unit is disconnected from the water lines, the vent or the circuit, and carried out.
Set and connect the new tank
We level the new tank, connect new flex lines and shutoff valves, and route the discharge pipe correctly.
Fire it up and test
We purge air, check every joint for drips, confirm the vent draws or the elements heat, and set the temperature.
A straightforward swap is often a half-day visit, but a vent rebuild or a new circuit can stretch it. Ask what your quote assumes.
Permits and scheduling
The City of Maryland Heights says permits can be pulled without plans for replacing water heaters up to 120 gallons, which includes a 50 gallon tank. Ask the building division at (314) 291-6550 how your job is handled, and we manage the permit step when it applies.
A planned swap is easier on your schedule and on your wallet than a failed tank in the middle of the night. If your heater is old and showing signs, booking a replacement before it leaks is a good plan, and the dispatcher can set a time that works. We cover Hazelwood and Chesterfield too, and our water heater replacement page explains how a visit works.
Standards behind a 50 gallon tank
Gas storage water heaters are built to ANSI Z21.10.1 and electric ones to UL 174, and both need a temperature and pressure relief valve under the manufacturer's installation standard. A 50 gallon tank is well under the 120 gallon limit the City of Maryland Heights lists for permits without plans.
50 gallon water heater questions
It depends on the water, the maintenance and the quality of the unit. A tank that leaks or rusts is finished regardless of age.
Yes, if there is a gas line and a vent path. The swap adds work for the gas line and flue, which affects the quote.
A periodic flush helps clear sediment, especially with moderately hard water. Follow the manufacturer's advice and have a plumber check the anode rod.
The first-hour rating matters more than the gallon number. A plumber can match it to your household's hot water use.
The city says permits can be pulled without plans for water heaters up to 120 gallons. Confirm the permit step with the building division at (314) 291-6550.