About HotWaterAtlas
HotWaterAtlas is a reference site for home water heating in the United States. It answers the questions people actually have when replacing a water heater: which units exist, how much hot water each really delivers for your household, what it costs to run, and what the installation requires.
The core of the site is a structured database of all 1084 ENERGY STAR certified water heaters — heat pump, gas tankless, and gas storage — across 61 brands, built from the U.S. EPA's public certification data. On top of that data we compute the things spec sheets leave out — annual running cost in dollars, real tankless flow at winter groundwater temperatures, household-size fit from first-hour ratings, and code-compliant breaker sizes.
What you'll find here
- Water heater directory — specifications for every certified model, each linked to its underlying EPA record.
- Best water heater by household — rankings sized from your peak hour, with first-hour rating and flow-rate math.
- Head-to-head comparisons between water heaters.
- Buying and installation guides — hand-written decision guides on sizing, fuel choice, efficiency, and installation.
- A plain-English glossary of water heating terms.
How the site is made
Specification pages are generated from the dataset by templates; guides, household sizing notes, and glossary entries are written and reviewed by people. The methodology page documents the data pipeline and every formula, and the editorial policy explains how content is produced and corrected.
HotWaterAtlas is independent: no manufacturer pays for placement, and rankings are computed from certification data alone. The site may earn affiliate commissions on some outbound links — see the affiliate disclosure.
Water heater certification data comes from the U.S. EPA ENERGY STAR program; HotWaterAtlas is not affiliated with or endorsed by the EPA. Found an error? Contact us.