Tank vs. Tankless Water Heaters for St. Louis Homes

The decision usually comes at a bad time

Most people shop for a water heater the morning theirs stops working or starts leaking. That's a stressful time to make a choice that lasts a decade or more. If your current heater is getting older, it's worth understanding the two main options now, so you know what you want before you're standing in a cold shower.

How a tank water heater works

A conventional tank heater stores a set amount of water — commonly 40 or 50 gallons in a typical home — and keeps it hot around the clock using a gas burner or electric elements. When you open a hot tap, hot water leaves the top of the tank and cold water refills the bottom to be heated.

How a tankless water heater works

A tankless (on-demand) heater has no storage tank. When you turn on a hot tap, water flows through a heat exchanger and a powerful burner or element heats it instantly. When you turn the tap off, the unit shuts down.

Factors that matter in St. Louis

A few local details shift the math:

• Cold incoming water in winter: groundwater temperatures drop in January and February, so a tankless unit has to raise water temperature further. Sizing for winter, not summer, is critical.
• Mineral content: water across much of the region carries minerals that build scale in both tanks and tankless heat exchangers. Flushing a tank and descaling a tankless unit on schedule protects either one; a water softener helps both.
• Basement installs: many St. Louis heaters sit in unfinished basements, which makes tanks easy to replace — and makes leak protection like a drain pan or shutoff sensor worth considering.
• Gas line size: older homes often have gas piping sized for a tank heater and furnace only. A tankless unit may need a larger line run from the meter.
• Venting: tankless units vent differently from tanks, and an old chimney flue usually can't be reused for them.

Which one fits your household?

Signs it's time to replace either type

Whatever you choose, these are signs your existing heater is near the end:

• Rust-colored hot water or rust around the base or fittings.
• Water pooling under the tank.
• Rumbling or popping sounds from sediment buildup.
• Hot water that runs out much faster than it used to.
• Frequent repairs on a unit that's already well into its expected life.

Get help sizing it right

A water heater that's too small leaves you cold; one that's oversized wastes money. We look at your household size, fixtures, gas or electric service and venting before recommending tank or tankless, and we'll give you upfront pricing for both if you want to compare. Call City & County Plumbing and Drain at (636) 243-8881.