Water Heater Replacement Cost: Tank vs Tankless

How Much Does Water Heater Replacement Cost?

Plan on about $800 to $1,500 for a standard tank and $1,200 to $3,500 for a tankless unit, installed, according to This Old House (updated June 12, 2026). These are national published estimates, not our quotes. Today's Homeowner's Washington, IL page lists water heater installation at $772 to $1,931, last updated February 25, 2025, and does not explain its method.

The gap between tank and tankless comes from the extra work around the unit, not only the unit itself.

Why Does Tankless Cost More Than a Tank?

Because a tankless heater is a different install. This Old House lists extras for gas models: gas line updates at $350 to $750, up to $800 more to upsize the gas pipe, and venting at $400 to $800. Electric models can need a new circuit at $200 to $600, or a panel upgrade at $1,000 to $2,000.

On top of that, the guide lists $100 to $500 to remove the old unit, $50 to $200 for permits, $74 to $150 for a safety inspection, and labor at $75 to $150 an hour over four to eight hours. A like-for-like tank swap usually reuses the existing gas line, flue and connections, which is why it costs less.

Operating cost narrows part of the gap. ENERGY STAR says a gas tankless unit saves about $95 a year over a gas storage tank for a family of four, and puts tankless life expectancy at 20 years. It rates the lifetime saving at about $1,800, which only pays back if the install premium is small and you stay in the house.

What Does Each Option Cost Over 20 Years?

Closer than the sticker price suggests, and the answer turns on which energy figure you trust. This table uses This Old House's 2026 numbers for gas units. It assumes two tanks at about 10 years each, inside the guide's 8 to 12 year range, and one tankless unit lasting the full 20.

On those numbers, tankless can win. There is a catch. This Old House's energy figures imply a saving of about $250 to $315 a year, roughly triple ENERGY STAR's $95. At ENERGY STAR's rate, the 20-year energy saving is near $1,900, and it no longer covers the higher install and the yearly cleaning. Treat the table as a way to test your own quotes, not a verdict. Our tankless vs tank guide covers the flow and comfort side.

Which Rebates Can Lower the Price?

Fewer than before. Federal credits are gone, and state programs have not opened. Here is the status, with a confirm-before-you-buy note on each:

• Ameren Illinois, gas. Our research brief lists a $50 rebate on a new ENERGY STAR gas storage or gas tankless water heater, one per household, bought by December 31 and applied for within 60 days. Confirm it on Ameren's site before you buy.
• Ameren Illinois, heat pump water heater. Energy Rebate Calculator, checked on July 31, 2026, lists an $800 retail rebate or a $1,150 contractor discount through a participating contractor, one per household per year. A heat pump unit is a different product with its own space and electrical needs.
• Federal 25C and 25D credits. The IRS says the energy efficient home improvement credit covers improvements made through December 31, 2025. It has expired.
• Illinois HOMES and HEAR. Energy Rebate Calculator reported that neither had launched as of July 31, 2026. Rebates are generally not paid for work done before a program opens, so recheck first.

The Illinois ENERGY STAR Appliance Rebate Program lists gas storage and gas tankless heaters, but Keep Warm Illinois gives no amount or launch date and says rebates will not be retroactive.

What We Look For Before Recommending Tank or Tankless

We start with the space and the gas line, not the brochure. A heater in a tight closet needs clearance for a tank and a flue, or room for a wall unit and a vent path. If you are in Peoria Heights, about 11 miles from our base, and your heater sits in a tight closet, the closet may decide the choice.

Then we ask how the household uses hot water: how many people, how many showers at once, and how long you plan to stay. We check the size of the gas pipe, the venting route and the water supply. Water hardness varies by supply and deep wells in this region usually run hard, so ask your utility's water quality report or test the water, because mineral scale hurts tankless heat exchangers.

The honest trade-off for most homes is simple. If the old tank has failed and the gas line and flue are sound, a like-for-like tank is the low-risk, low-cost choice. Tankless earns its premium when you plan to stay, when floor space matters, and when the descaling is something you will keep up with. A tankless unit that never gets flushed gives up the long life that justified the price.

You get a clear, upfront quote for the option that fits, and you can compare it with the other. Our water heater installation page explains the visit, and tankless water heaters covers the other side.

Is It Time to Replace or Repair?

Replace when the tank leaks from its shell. A leak at a fitting or valve is a repair. Our guide to a leaking water heater shows how to tell the difference, and the water heater repair page lists the common fixes. Repair costs run well below replacement, with Today's Homeowner listing $118 to $591 for repairs in Washington.

Timing also moves the price. Today's Homeowner's emergency guide lists evening work at time and a half and weekends at double time as a published industry pattern. A heater replaced on a weekday, after two quotes, usually costs less than one replaced because it failed on a Saturday night. The trade-off is giving up whatever life the old tank had left.

Does the 2029 Federal Rule Change the Math?

Only if you plan to buy after it starts. One manufacturer's summary says new federal standards apply to heaters produced on and after May 6, 2029. Electric tanks over 35 gallons would need heat pump technology, gas tanks of 20 to 55 gallons see a slight efficiency rise, and gas tankless units were left out of this rule for now. Do not replace a sound heater because of a 2029 date, but an owner of a large electric tank should keep it in mind.

Get a Price for the Heater You Actually Need

A published range tells you whether a quote is sane. Your gas line, flue, closet and hot water use decide the real number. Call (209) 563-1400, send a photo of the label if you can, and tell us how many people share the hot water. You get a clear, upfront quote before work starts, and if your heater has already failed, close the cold inlet and cut the power or gas first.