Water heater sizing Last reviewed June 2026

What Size Water Heater for a 1-2 Person Household?

By the WhatSize editorial team 4 min read Standards-reviewed

TL;DR

A 1-2 person household needs a 30-40 gallon storage tank water heater. For tankless, a 4.3 GPM model like the EcoSmart ECO 18 is sufficient. Consider a 40-gallon if you take back-to-back showers.

Looking for a different size? See What Size Water Heater for a 3-4 Person Household? or browse all water heater sizing guides.

Sizing for Small Households

For 1-2 people, water heater sizing is straightforward. The DOE First Hour Rating (FHR) standard recommends 30-40 gallons for small households. A 30-gallon tank provides about 30-35 gallons of hot water in the first hour — enough for 1-2 showers plus hand washing. A 40-gallon tank gives you more headroom for back-to-back showers or occasional guests.

If you're considering tankless, a unit rated for 4.3 GPM (gallons per minute) like the EcoSmart ECO 18 can handle one shower and a sink simultaneously — more than enough for a couple.

Top picks for this size

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You can also consult a local contractor for product recommendations suited to your region and installation requirements. See our full Disclaimers.

Best Options for 1-2 Person Households

Storage tank: Rheem Performance 40 Gal (~$459) — best overall value, 6-year warranty
Tankless electric: EcoSmart ECO 18 (~$499) — compact, 4.3 GPM, self-modulating
Gas tankless: Rinnai RU160iN (~$1,299) — 7.5 GPM if you plan for future needs

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