Most Houston homes still have a tank water heater in the garage, a closet or the attic. It holds a tank full of water and keeps it hot all day and all night, whether anyone is using it or not. A tankless water heater works a different way. So is it worth switching? For a lot of homes, yes. For some, it takes careful sizing. Here is how I would think it through.
How a tankless water heater works
The U.S. Department of Energy explains it simply. A tankless heater makes hot water only when you need it. When you turn on a hot tap, cold water flows through the unit and a natural gas burner or an electric element heats it on the way through. When you turn the tap off, it stops.
Because there is no tank, there is no stored hot water slowly losing heat. The Department of Energy calls those "standby" losses and says skipping them can save money. It also says a tankless heater gives you a constant supply of hot water, so you are not waiting for a tank to heat back up after a long shower.
What the Department of Energy says about efficiency
Here are the Department of Energy's own figures. For homes that use 41 gallons of hot water a day or less, a tankless heater can be 24% to 34% more energy efficient than a regular tank heater. For homes that use a lot of hot water, around 86 gallons a day, it can be 8% to 14% more efficient.
So the savings are real, but they depend on how your family uses hot water. A smaller household tends to see the bigger percentage.
How long they last
The Department of Energy says most tankless heaters have a life expectancy of more than 20 years, and their parts can often be replaced to stretch that further. It puts tank heaters at 10 to 15 years. It is also straight about cost: a tankless heater costs more up front, but it usually lasts longer and costs less to run, which can make up for the higher price.
I do not publish prices, because the right unit and the install work depend on your house. I will give you an upfront price for yours.
Where tankless falls short
A tankless heater never runs out, but it can only heat so much water at once. The Department of Energy says most units deliver about 2 to 5 gallons of hot water a minute, and gas units deliver more than electric ones. It warns that running a shower and the dishwasher at the same time can stretch one to its limit.
That is a sizing question. A unit has to be matched to how many showers, sinks and appliances your home runs at the same time. Some homes use two units. The Department of Energy notes that extra units cost more and may not always be worth it, so this is a conversation to have before you buy, not after.
One more detail from the Department of Energy: a gas tankless heater with a standing pilot light can waste some of the energy it saves. It suggests looking for a model with an intermittent ignition device instead of a pilot that stays lit.
Why Houston's hard water matters
The U.S. Geological Survey says that when hard water is heated, scale can form inside the water heater. That scale can shorten the life of the equipment, raise the cost of heating water, and lower the efficiency of electric water heaters.
If you are on City of Houston water, that matters here. The City's Houston Water Quality Report 2025 lists average hardness at 135.5 mg/L, which falls in the USGS "hard" range. If you are on a MUD, check its yearly water quality report, because your number may be different. I explain how in my post on hard water in northwest Houston.
The Department of Energy says regular maintenance can add years to any water heater and keep it efficient, and to follow the owner's manual. With hard water, a water softener ahead of the heater is worth asking about too.
Choosing who installs it
The Department of Energy says a good install depends on fuel type, climate, local building codes and safety, especially with gas. It suggests getting estimates in writing, asking for references, and asking whether the company will get a local permit if one is needed. That is good advice for any installer you talk to, me included.
So, is it worth switching?
It is often worth a close look if your tank heater is getting old, if you want to stop paying to keep a tank hot all day, or if you want the space back. It takes more planning if your home runs a lot of hot water at once.
Want to know if a tankless water heater fits your home? Ask me for a free quote. Call me at (346) 649-1463 and I will talk it through with you.
Questions about your water? Call Mathew.
Free quote, honest upfront pricing, and a system that fits your house.
Sources
- U.S. Department of Energy, Energy Saver, "Tankless or Demand-Type Water Heaters" (archived copy, 30 Jun 2026). Read 22 Oct 2026.
- U.S. Geological Survey, Water Science School, "Hardness of Water". Read 22 Oct 2026.
- City of Houston, Houston Public Works, Houston Water Quality Report 2025, Main System (TX1010013). Read 20 Oct 2026, re-checked 22 Oct 2026.