Why Montana water heaters work harder, and how to make one last
A water heater in Montana has more work to do than one in a milder state, and hard water in some cities shortens its life further. What follows is why, how to maintain one, the signs it needs repair instead of replacement, safe temperature settings, whether tankless makes sense here, and what to do if it leaks.
- Last updated 2026-09-25
- Primary sources only
- 11 sources
Why Montana is harder on a water heater
Why a Montana water heater works harder
A storage or tankless water heater's whole job is to raise incoming water to a target temperature, and DOE's own sizing example assumes the incoming water is 50°F unless you know otherwise. Montana's winters push outdoor temperatures well below that: NOAA's state climate summary puts the average January low at 15 to 18°F in Missoula, Billings and Great Falls, and the state holds the record low for the lower 48, −70°F at Rogers Pass in 1954. Colder ground and surface water in weather like that means a bigger temperature rise to reach the same 120°F tap, and a bigger rise takes more energy, and more run time, no matter what fuel the water heater burns.
Hard water, sediment, and the anode rod
What hard water does to a water heater
MSU Extension's water-quality program names the mechanism directly: hardness minerals leave deposits in hot water heaters and scaling on sinks and fixtures, which leads to reduced water pressure and shorter hot water heater life. MSU classifies total hardness on a four-step scale: 0 to 60 mg/L is soft, 61 to 120 mg/L is moderately hard, 121 to 300 mg/L is hard, and anything over 300 mg/L is very hard. One grain per gallon equals 17.1 mg/L.
- MSU Extension Water Quality, "Hardness" (accessed 2026-09-25)
Missoula, Billings and Great Falls each publish their own water hardness. Bozeman's and Helena's water departments do not publish a usable figure, so they are left out here rather than guessed.
Missoula
163 mg/L average total hardness (9.45 grains per gallon)
Hard, on MSU Extension's scale
Missoula Water 2025 water quality report, 2024 sampling (2025)Great Falls
145 mg/L in finished water
Hard, on MSU Extension's scale
City of Great Falls consumer confidence report (2025)Billings
53.5 to 197 ppm, no annual average published
Moderately hard to hard, on MSU Extension's scale
City of Billings annual drinking water quality report (2025)Three routine jobs keep a storage water heater running efficiently and closer to its full lifespan.
Flush the tank
DOE's maintenance guidance for storage water heaters calls for flushing a quart of water from the tank every three months, the first of three routine jobs it lists for keeping one running efficiently.
- U.S. Department of Energy, Energy Saver, "Storage Water Heaters" (archived) (archived 2026-05-01)
Check the temperature and pressure relief valve
The same DOE list calls for checking the temperature and pressure relief valve every six months.
- U.S. Department of Energy, Energy Saver, "Storage Water Heaters" (archived) (archived 2026-05-01)
Inspect the anode rod
DOE's list also calls for inspecting the anode rod every three to four years, depending on the type and model of water heater.
- U.S. Department of Energy, Energy Saver, "Storage Water Heaters" (archived) (archived 2026-05-01)
How long a water heater lasts
How long does a tank water heater last?
Rheem's own guidance puts the typical lifespan of a traditional tank water heater at 8 to 12 years. DOE's figure for a storage water heater is close: 10 to 15 years.
- Rheem Manufacturing Company, "Water Heater Lifespan: When to Repair vs. Replace" (accessed 2026-09-25)
- U.S. Department of Energy, Energy Saver, "Tankless or Demand-Type Water Heaters" (archived) (archived 2026-05-01)
How long does a tankless water heater last?
DOE puts a tankless water heater's life expectancy at more than 20 years, and notes that its easily replaceable parts can extend that further. Rheem's figure is close: 15 to 20-plus years with proper care.
- U.S. Department of Energy, Energy Saver, "Tankless or Demand-Type Water Heaters" (archived) (archived 2026-05-01)
- Rheem Manufacturing Company, "Water Heater Lifespan: When to Repair vs. Replace" (accessed 2026-09-25)
Repair or replace?
Rheem's own signs
Water pooling around the tank itself
Rheem is direct about what this means: pooling water around the tank body itself often indicates internal corrosion that has eaten through the metal, and once a tank starts to deteriorate from the inside, replacement is the only safe and cost-effective option. A leak from a loose fitting, a failing temperature and pressure relief valve, or condensation is a different, and often repairable, problem.
Rusty, muddy, or foul-smelling hot water
Rheem lists rusty, muddy, or foul-smelling hot water as a warning sign that the water heater is in trouble.
Rumbling, popping, or cracking sounds
Rheem attributes rumbling, popping, or cracking sounds during operation to sediment buildup in the tank, the same buildup DOE's maintenance schedule addresses with a quarterly flush.
- Rheem Manufacturing Company, "5 Signs Your Water Heater Is Going Bad (And What to Do About It)" (accessed 2026-09-25)
- U.S. Department of Energy, Energy Saver, "Storage Water Heaters" (archived) (archived 2026-05-01)
Running out of hot water faster than it used to
Rheem names running out of hot water faster than usual as a sign of an underlying problem worth having a plumber look at.
It's old and the same problem keeps coming back
Rheem treats a water heater's age, 10 to 15-plus years, combined with a recurring issue as a strong signal on its own. A younger unit with a problem limited to one replaceable part, a thermostat, an element, or a pilot assembly, is the case where repair is the right call.
- Rheem Manufacturing Company, "Water Heater Lifespan: When to Repair vs. Replace" (accessed 2026-09-25)
Setting the temperature safely
120°F, per CPSC and DOE
What temperature should it be set to?
CPSC urges all users to lower their water heaters to 120 degrees Fahrenheit, both to prevent scalds and to conserve energy. DOE's own sizing guidance uses the same 120°F figure as the target for most household uses, and warns that 140°F, sometimes used for a dishwasher with no internal heater, increases the possibility of scalding.
How fast can hot water actually burn someone?
CPSC's own figures: most adults suffer third-degree burns after a two-second exposure to 150°F water, six seconds at 140°F, or thirty seconds at 130°F. Even at 120°F, CPSC says a five-minute exposure could still cause a third-degree burn, which is why hand-testing water before bathing a child, and never leaving one unsupervised near a tap, matters regardless of the thermostat setting.
Tankless in a cold climate
Does a tankless water heater work in a Montana winter?
Yes, but incoming water temperature changes how much hot water it can deliver at once. DOE sizes a tankless unit by the temperature rise it needs to produce, the incoming water temperature subtracted from the target output, and its own worked example assumes 50°F incoming water unless you know otherwise. DOE also notes that a faster flow rate or a cooler inlet temperature can each reduce the water temperature at the most distant faucet, which is the practical effect a cold Montana winter has: the same unit delivers less hot water, or at a lower temperature, than it would off a warmer supply.
- U.S. Department of Energy, Energy Saver, "Sizing a New Water Heater" (archived) (archived 2026-05-01)
How much hot water can a tankless unit actually deliver?
DOE puts a typical tankless flow rate at 2 to 5 gallons per minute, with gas-fired models producing higher flow rates than electric ones, and notes that even the largest gas-fired model can struggle to supply multiple simultaneous uses, a shower and a dishwasher at once, in a large household.
Is tankless more efficient here than a storage tank?
DOE's figures: for a household using 41 gallons of hot water or less a day, a demand water heater can be 24% to 34% more energy efficient than a conventional storage tank. For a household using around 86 gallons a day, the gain is smaller, 8% to 14%. Tankless units avoid the standby heat losses a storage tank has, though a gas-fired tankless model with a standing pilot light can waste some of that gain on the pilot.
If it's leaking
Shut off the water first
Not every leak means the tank has failed. Rheem's own guidance notes that some leaks come from a loose fitting, a failing temperature and pressure relief valve, or condensation, all of them repairable. A leak from the tank body itself is the one that means replacement. Either way, shut off the water first.
How to shut off the water in a Montana home
Shutting the main valve stops the damage while you wait. In most Montana houses the main shutoff is inside, where the water service comes through the foundation, because an outside valve would freeze.
- 01
Find the main shutoff
Look where the water line enters the house: the basement or crawl space wall on the street side, near the water heater, or in a utility room. Older Montana homes often have it in the crawl space rather than a basement.
- 02
Turn it off
A round handwheel turns clockwise until it stops. A lever-style ball valve turns a quarter turn so the handle sits across the pipe rather than along it.
- 03
If you cannot reach the main, use the local stop
A single leaking toilet, sink or water heater has its own shutoff on the supply line right at the fixture. Turning that one off isolates the fixture without cutting water to the rest of the house.
- 04
If there is no interior valve, use the curb stop
The curb stop sits in a small metal or plastic box at the property line, usually under a round lid marked water. It takes a long curb key rather than a hand, so this is normally the utility's job to operate.
- 05
Open a low faucet to drain the lines
With the supply off, open the lowest faucet in the house. That drops the pressure in the pipes and lets the standing water out at a controlled point instead of through the leak.
- 06
Cut power if water is near electrical
If water is running near outlets, a panel, or a light fixture, switch off the breaker for that circuit before going into the water.
When to call a plumber
- Water is pooling around the base of the tank itself.
- There's no hot water at all and the pilot won't stay lit.
- The temperature and pressure relief valve is dripping or won't stop discharging.
- The unit is 10 years or older and a problem keeps coming back.
Sources
- U.S. Department of Energy, Energy Saver, "Storage Water Heaters" (archived) (archived 2026-05-01)
- U.S. Department of Energy, Energy Saver, "Tankless or Demand-Type Water Heaters" (archived) (archived 2026-05-01)
- U.S. Department of Energy, Energy Saver, "Sizing a New Water Heater" (archived) (archived 2026-05-01)
- U.S. Consumer Product Safety Commission, Publication 5098, "Avoiding Tap Water Scalds" (2012)
- MSU Extension Water Quality, "Hardness" (accessed 2026-09-25)
- NOAA NCEI, Montana State Climate Summary 2022 (2022)
- Rheem Manufacturing Company, "5 Signs Your Water Heater Is Going Bad (And What to Do About It)" (accessed 2026-09-25)
- Rheem Manufacturing Company, "Water Heater Lifespan: When to Repair vs. Replace" (accessed 2026-09-25)
- Missoula Water 2025 water quality report, 2024 sampling (2025)
- City of Great Falls consumer confidence report (2025)
- City of Billings annual drinking water quality report (2025)
DOE's consumer water-heater pages went offline sometime between May and July 2026, so the three DOE sources above are linked to their last-known-good Wayback Machine snapshot rather than a dead energy.gov URL. Bozeman's water department blocks automated access to its own published report, and Helena's current report does not include a hardness figure, which is why neither city appears in the hardness section above.
Montana plumbing rules, with sourcesOne call instead of nine.
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