Water Heater Replacement Cost Guide: Tank vs. Tankless
What you'll pay to replace a 50-gallon tank, when tankless makes financial sense, and the venting upgrades that catch homeowners off guard.
Replacing a standard 50-gallon gas tank water heater runs $1,500–$3,000 nationally, while switching to a tankless unit roughly doubles that to $3,500–$6,800. The decision between them is less about the equipment and more about how much hot water your household actually uses.
When tank still wins
Tank units are simpler, faster to install (3–4 hours vs. 6–10 for tankless), and don't require venting or gas line upgrades. For households of 1–3 people in homes with adequate gas service, a high-efficiency tank usually has the best total cost of ownership over 10 years.
The biggest hidden cost on a tank swap is bringing the install up to current code — modern installs require a thermal expansion tank, an updated T&P drain line, and (in many jurisdictions) a drip pan with leak alarm.
When tankless pays off
Tankless wins for households of 4+, homes where the tank lives in finished space (no more 50-gallon flood risk), and in regions with high gas prices. They last 18–22 years vs. 10–12 for tanks, and the federal tax credit covers 30% of cost up to $600 on Energy Star units.
Watch for these upcharges: gas line upgrade from 1/2" to 3/4" ($400–$1,200), stainless venting kit ($300–$600), and a soft-water installation in hard-water markets to keep the heat exchanger from scaling up.
FAQs
How long does a water heater last?
Standard tanks: 8–12 years. High-efficiency tanks: 10–14. Tankless: 18–22 with annual descaling.