Heat Pump Water Heaters Cut Your Biggest Electric Bill

Every electric water heater that carries ENERGY STAR certification today is a heat pump model — and ENERGY STAR estimates that switching to one from a standard electric resistance tank cuts water-heating energy use by about 70%, saving a household of four roughly $550 a year and over $5,600 across the unit's lifetime.

What a heat pump water heater actually does

A standard electric water heater makes heat directly, by running electricity through a resistance element — the same principle as a toaster. A heat pump water heater instead moves existing heat out of the surrounding air into the tank, the same way a refrigerator moves heat out of its interior. Moving heat takes far less energy than generating it, which is where the 70% savings figure comes from.

That efficiency gap is large enough that, in WattCost's certified dataset, every single one of the 566 electric water heaters that has earned ENERGY STAR certification is a heat pump model. Standard electric resistance tanks simply don't meet the efficiency bar for certification — if you're shopping by the ENERGY STAR label, you're shopping among heat pump models by default.

The range within certified models: 643–1,741 kWh

Even limited to certified heat pump models, annual energy use spans a wide range — from 643 kWh a year for compact units like the Rheem PROPH40 T2 (36-gallon storage, a 3.45 Uniform Energy Factor) up to 1,741 kWh for the largest-capacity models. Tank size and first-hour rating (how much hot water is available before the tank runs out) are the biggest drivers of that spread — a bigger tank generally means more standby heat loss and more energy used per year, regardless of the heat pump technology itself.

At the US average electricity rate, the median certified water heater costs $203.74 a year to run — the highest median annual cost of any appliance category on this site, ahead of room air conditioners and clothes dryers. See the most efficient certified water heaters for the full ranked list.

Why this is usually the highest-leverage upgrade in a home

Because water heating runs year-round and represents the single biggest median cost category in WattCost's data, a heat-pump upgrade compounds every month rather than just during a cooling or heating season. A 70% cut applied to a $200+/year baseline is a meaningfully different number than the same percentage cut applied to a $30/year TV or a $9/year computer monitor.

What the certified figure assumes

The annual kWh figure comes from the DOE Uniform Energy Factor test, which simulates a typical household's daily hot-water draw pattern. Only electric models, including heat-pump units, are listed in this dataset — gas and propane water heaters are excluded because their running cost is mostly fuel, not electricity, and a kWh figure would understate or mislead.

FAQ

Are all ENERGY STAR certified electric water heaters heat pump models? Yes, based on the current certified dataset — none of the 566 certified electric water heater models use standard resistance-only heating.

How much less energy does a heat pump water heater use? About 70% less than a standard electric resistance tank, per ENERGY STAR, translating to roughly $550 a year in savings for a household of four.

Why do certified heat pump water heaters still range from 643 to 1,741 kWh a year? Mostly tank size and first-hour rating — larger tanks lose more standby heat and serve more draw, which increases annual energy use even among efficient heat-pump units.

Do gas water heaters show up in this data? No — gas and propane water heaters are excluded from WattCost's electric water heater figures because their running cost is mostly fuel, not electricity.

Where does the 70% savings figure come from? ENERGY STAR's own benefits and savings page for heat pump water heaters.