How much does it cost to replace a 30-gallon water heater?

Q: How much does it cost to replace a 30-gallon water heater?

Replacing a 30-gallon tank water heater costs $550 to $2,100 installed according to Fixr (January 2026), and $700 to $2,100 if it is a gas unit. A 30-gallon tank suits one or two people. The important number is the comparison: a 40-gallon tank costs $550 to $2,300, so going one size down saves almost nothing on the purchase and gives up a third of the capacity.

The published range

Source	30-gallon tank, installed	Date
Fixr, all fuel types	$550 to $2,100	January 2026
Fixr, gas units only	$700 to $2,100	January 2026

This Old House does not publish a 30-gallon figure. Its size table starts at 40 gallons, and its sizing guidance puts a household of one to two people at a 30- to 40-gallon tank. That gap is itself information: 30-gallon tanks are a thin part of the market, which is why fewer cost guides break them out.

The comparison that decides it

This is the one number worth taking away from this page.

Tank size	Installed, all fuels	Installed, gas	Household
30 gallons	$550 to $2,100	$700 to $2,100	1 to 2 people
40 gallons	$550 to $2,300	$700 to $2,300	1 to 4 people
50 gallons	$700 to $2,500	$900 to $2,500	3 to 5 people

All figures from Fixr, January 2026.

The low end is identical. The high end differs by $200 between 30 and 40 gallons. For that $200 you get ten more gallons of storage and a tank that still works if a second person moves in. Neither source publishes a case where a 30-gallon tank is meaningfully cheaper to buy.

Our assumption, stated as such: the reason the prices barely differ is that the tank shell, the burner or element, the controls, the anode rod and the labor hours are nearly the same for both sizes. Only the steel and the insulation scale with capacity, and those are a small share of the price. Neither source states this, so treat it as our reading rather than published fact.

When a 30-gallon tank is still the right call

It is what fits. The usual reason to buy 30 gallons is a closet, an alcove or an under-counter space that a 40-gallon tank does not fit. A 50-gallon tank runs 20 to 22 inches in diameter and 50 to 60 inches tall (Fixr, January 2026); a 30 is shorter and narrower. If the space is the constraint, the capacity question is already settled.

A single-occupant apartment or a guest suite. One person with one bathroom and no bathtub will not empty a 30-gallon tank in normal use.

A point-of-use second heater. A 30-gallon tank near a distant bathroom can be cheaper than re-plumbing hot water across the house.

Where the money goes

Line item	Range	Source
Labor, tank swap	$300 to $1,500 (18% to 50% of the total)	Fixr
Plumber hourly rate	$45 to $200	Fixr
Plumber hourly rate	$40 to $200, job takes 1 to 3 hours	This Old House
Permit and inspection	$50 to $200	This Old House
Permit, wider published range	$25 to $1,500	Fixr
Removal and disposal of old tank	$100 to $300	This Old House
Removal and disposal of old tank	$75 to $500	Fixr
Expansion tank, if code requires it	$40 to $150	This Old House
Power vent, gas units	$300 to $1,000	Fixr

The two permit ranges are not a contradiction. Fixr's $1,500 top end is explicitly for jobs that add a new gas line or make major plumbing changes. For a like-for-like swap, This Old House's $50 to $200 is the realistic figure.

How to read a quote for this job

Ask the contractor to quote the 40-gallon unit alongside the 30. If the difference is under $200 and the tank fits, the larger unit is the better buy on every published number. If the difference is larger than $200, ask what drives it, because neither published source supports a big gap at this size.

Sources

Price figures are national US ranges from the sources above as of the date shown. Your local price depends on labor rates, permits and site conditions. Read how we get our numbers.