When to replace instead of repair
A conventional tank water heater lasts 8 to 12 years in the St. Louis area. Hard water shortens that lifespan by accelerating sediment buildup and anode rod depletion.
Rusty hot water, popping or rumbling from the tank, water pooling at the base, or a unit past ten years with a failed component are all replacement signals. A leaking tank is never repairable; the steel shell has corroded through.
Tank water heater pricing
A standard 40- or 50-gallon gas tank water heater installed in the St. Louis metro typically costs $1,400 to $2,600. Electric tanks generally run $1,200 to $2,200.
Price varies with venting requirements, expansion tank installation, drain pan and code upgrades, and whether the unit sits in a basement with easy access or a tight closet on an upper floor. Power-vent models add roughly $400 to $900.
Tankless pricing and tradeoffs
A gas tankless unit installed usually runs $3,500 to $6,500 in this market. The higher cost reflects the larger gas line often required, new stainless venting, and condensate handling.
Tankless makes sense for households that run out of hot water, want to reclaim floor space, or plan to stay in the home long enough to recover the cost through efficiency. It is less compelling for a small household replacing a working tank on a budget.
Local code and permit notes
Most St. Louis area municipalities require a permit and inspection for water heater replacement. Common code items include a thermal expansion tank where a pressure-reducing valve or backflow preventer is present, a properly sloped temperature and pressure relief discharge line, sediment trap on the gas line, and correct venting clearances.
Confirm that the contractor pulls the permit. Unpermitted work can complicate an insurance claim after a leak and often surfaces during a home inspection at resale.
Annual maintenance checklist
Flush two to three gallons from the drain valve every six months, or fully flush the tank annually, to remove sediment. Test the temperature and pressure relief valve once a year by lifting the lever briefly and confirming it reseats.
Inspect the anode rod every two to three years and replace it when heavily depleted; a $40 rod can add years to a tank. Set the thermostat to 120 degrees for a balance of safety, scald prevention, and efficiency, and check the area around the unit for moisture each season.
Frequently asked questions
How long does water heater installation take?
A straightforward tank swap usually takes two to four hours. A first-time tankless conversion often takes a full day due to gas line, venting, and condensate work.
What size water heater do I need?
A household of two to three people is generally served by a 40-gallon tank, four to five people by a 50-gallon tank. Tankless units are sized by flow rate and incoming water temperature instead.
Does hard water affect water heaters in St. Louis?
Yes. Local water hardness accelerates sediment accumulation, so annual flushing matters more here than in soft-water regions.
Sources and further reading
Price ranges in this guide come from quotes and invoices shared with STL Home Pros by St. Louis area homeowners and contractors. Technical and climate references are listed below.
About the author
Nick Cascani is a New York native who has called St. Louis home for the last few years. He believes getting professional home service should be simple and convenient, and he writes these guides to help local homeowners make confident decisions about their HVAC, plumbing, and foundation projects.
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