Chain of Rocks and Howard Bend
The City of St. Louis Water Division runs two treatment plants. Chain of Rocks, on the north riverfront, draws from the Mississippi just downstream of where the Missouri joins it. Howard Bend, which the city owns even though it sits out in Maryland Heights in St. Louis County, draws straight from the Missouri River. Both plants settle out the heavy load of silt these rivers carry, soften the water with lime, then filter and disinfect it before it flows through mains into city neighborhoods.
St. Louis has used lime softening for more than a century, and the result is water that is moderately hard rather than truly hard. Tanks still collect sediment, partly mineral scale and partly fine silt that sneaks through after a flood crest, but a Tower Grove South gas tank will usually build up more slowly than one on suburban well water. Electric tanks and tankless units benefit from a yearly check of the elements or heat exchanger all the same.
River temperature is the larger factor. When the Mississippi runs icy in January, water reaching a Carondelet basement can be close to 40°F. After a hot, dry August it can be in the 80s. That gap means the same heater delivers far more hot water in September than it does after New Year's Day.
Red brick, old basements
St. Louis is a brick city. Its clay deposits and nineteenth-century building rules left street after street of solid masonry homes: row houses in Soulard and Lafayette Square, flounder houses tucked behind them, two-family and four-family flats across Benton Park, Fox Park and Dutchtown, and bungalows in Bevo Mill, Princeton Heights and St. Louis Hills. The Central West End and the private places off Lindell and Forest Park hold grand brick mansions with deep cellars.
Nearly all of these homes have basements with limestone or brick foundation walls, and many have dirt or patched concrete floors in the corners. The water heater usually stands near the old coal chute or the floor drain. Moisture seeping through the walls during spring rains keeps these spaces damp, which speeds rust on burner assemblies and tank bottoms. Low ceilings, narrow stairs with a turn at the bottom, and brick arches between rooms make carrying a 50-gallon tank in or out a real job.
In two-family flats along Gravois or Cherokee Street, each unit typically has its own heater, side by side in a shared basement. Some four-families on the South Side still have one large heater serving everyone, which is a recipe for complaints in winter.
Problems St. Louis plumbers handle most
- Rusted burners and tank bottoms in damp limestone basements in Soulard, Benton Park and Dutchtown.
- Flooded heaters after flash floods overwhelm MSD sewers and push water up through basement drains.
- Cold winter showers in South Side flats where a small tank faces near-40°F river water.
- Draft trouble in tall brick chimneys after a furnace upgrade leaves the heater venting alone.
- Corroded galvanized and old copper connections at the heater in homes that were never fully repiped.
- Tight-stair swaps in Lafayette Square and Shaw cellars where a replacement tank barely fits.
What St. Louis homeowners typically pay
| Job | Typical St. Louis range | Notes |
|---|---|---|
| Thermocouple or pilot assembly | $150–$300 | |
| Gas control valve | $350–$625 | |
| Flush and sediment clean-out | $110–$250 | |
| Replace corroded supply connections | $150–$450 | Galvanized nipples are common culprits |
| Chimney liner or vent correction | $400–$1,600 | Tall three-story flues cost more |
| 40–50 gallon gas tank replaced | $1,400–$2,900 | Building Division permit included by most |
| Tankless gas installation | $3,300–$6,200 | Gas line and venting work can add more |
Rates in St. Louis are moderate for a large metro. Basements with turning stairs and brick arches, relining a three-story chimney, or a call on a holiday weekend after a storm all push costs toward the top of these ranges. A clean swap in a St. Louis Hills bungalow with straight stairs lands lower.
City permits and the County line
Missouri does not license plumbers statewide, so local governments handle it. Inside the City of St. Louis, plumbers hold city-issued licenses, and swapping a tank requires a permit from the Building Division. A city inspector then checks the gas connection, the flue, the temperature and pressure relief discharge and the overall installation.
One quirk confuses newcomers: the City of St. Louis and St. Louis County are completely separate governments, and have been since the city split off in 1876. Clayton, Kirkwood, Webster Groves and University City are in the County, not the City. Most of the County gets its water from Missouri American Water, not the city Water Division, and the County runs its own plumbing licensing and permits for unincorporated areas and many of its municipalities. Make sure your plumber is licensed for the jurisdiction where your house actually sits, and that the right permit is in the quote.
Flash floods and basement backups
Heavy summer storms are a real hazard for St. Louis heaters. In July 2022 the region saw record-setting rainfall that flooded basements across the city and county within hours. The Metropolitan St. Louis Sewer District, MSD, runs combined sewers in much of the older city, and when they surcharge, water can rise through floor drains right beside the heater.
If water has reached the burner or gas control, turn the gas off at the heater and do not relight it. A submerged control valve or burner is normally replaced, and often the whole heater along with it. Owners in flood-prone blocks can ask a plumber about raising the heater on a stand or adding a backwater valve. See our page on leaking water heaters for what to check after the water drains.
Venting, chimneys and Spire gas
Tall brick chimneys in South City flats and Central West End homes were built for coal furnaces. Once a modern furnace vents out the side wall through PVC, a lone water heater is stuck exhausting into a wide masonry stack that drafts poorly and lets moisture eat at the mortar. A sized liner, a power-vent tank or a direct-vent model solves it, and city inspectors will look at venting when a permit is pulled.
Spire delivers natural gas across St. Louis and responds to suspected leaks around the clock. Ameren Missouri supplies electricity. Ameren and Spire have both promoted efficient equipment at times, so review their present programs before settling on a condensing gas tank or a heat pump model.
Repair, replace or size up
Because the Water Division softens its supply, plenty of St. Louis gas heaters last a dozen years when the basement stays dry. Under about eight years, fixing the pilot, thermocouple or control is generally worth it. A rusted base, a tank that sat in floodwater, or a heater that never keeps up in January points toward replacement. Families in two-bath South Side homes usually do better with a 50-gallon gas tank than a 40.
Around St. Louis
Clayton, University City, Maplewood, Richmond Heights, Webster Groves and Kirkwood are separate municipalities in St. Louis County, most served by Missouri American Water, with permits coming through the County or the municipality depending on the city. Florissant and Ferguson to the north fall under County rules as well. Across the Mississippi, East St. Louis, Belleville and Granite City are in Illinois, where plumbers need an Illinois state license.
Water heater questions from St. Louis
Where does St. Louis city water come from?
The Water Division treats Mississippi water at Chain of Rocks and Missouri River water at Howard Bend, softening both with lime.
I live in Kirkwood. Do City of St. Louis rules apply to me?
No. Kirkwood is in St. Louis County, a separate jurisdiction. Water there typically comes from Missouri American Water, and permits run through the County or the municipality.
Who issues water heater permits inside the City of St. Louis?
The city's Building Division issues the plumbing permit, and a city inspector checks the finished installation.
My basement flooded and the heater got wet. Can I just relight it?
No. Keep the gas off and have a licensed plumber inspect it. Submerged burners and gas controls are normally replaced.
Why does my South City flat run out of hot water only in winter?
River water can arrive near 40°F in January, so the heater needs far more energy per gallon. A bigger or separate heater usually solves it.
Is my old galvanized pipe hurting the water heater?
Corroded galvanized nipples at the heater can leak and restrict flow. Plumbers often replace them with dielectric fittings during a repair.
There is a rotten-egg smell by the basement heater. What now?
Get everyone out of the house first, then phone Spire's around-the-clock leak line from a neighbor's porch. Once Spire clears it, a plumber can fix the heater.