40-Gallon Water Heaters

The 40-gallon water heater is the volume size for 2–3 person households — second only to 50-gallon in residential install volume. The 40G saves $30–$80 upfront vs the 50G and fits the same standard 22"-diameter footprint with slightly less height. For 1-bathroom homes and smaller households, 40G is often the right sizing.

Top 40-gallon picks by fuel

Gas 40-gallon

• Rheem Performance Platinum 40G Gas (XG40T12HE40U0) — 12-year warranty, EcoNet WiFi.
• Rheem Performance Plus 40G Gas — 9-year warranty.
• Rheem PROG40-38N-RH62 — contractor channel, 8-year.
• AO Smith Signature Premier 40G (GCV-40-300) — 9-year, Coregard anode.
• Rheem Performance Power Vent 40G (XG40T06PV40U0) — for closet installs without chimney.

Electric 40-gallon

• Rheem Performance 40G Electric (XE40M06ST45U1) — 6-year, volume entry.
• AO Smith Signature 100 40G Electric (EJC-40) — Lowe's primary.
• Rheem Marathon 40G (MR40245) — limited-lifetime polybutene.
• Bradford White 40G Electric (M-I-40L6DS) — plumber-channel.

Short-form 40-gallon (low-clearance installs)

• Rheem 40G Short Gas (XG40S06EC34U0) — 50" height instead of 60".
• Rheem 38G Short Gas — even tighter clearance, slight capacity sacrifice.

40G vs 50G — which to choose

• Choose 40G: 2–3 person households, single bathroom, low simultaneous demand, tighter clearance, $30–$80 budget saving
• Choose 50G: 3–4 person households, 2 bathrooms, morning shower stacking, the volume default

The marginal cost of stepping up from 40G to 50G is small enough that most buyers default to 50G as insurance against future demand growth. The 40G is the right pick when capacity needs are genuinely modest.

40G tankless equivalents

For 40G-replacement applications considering tankless:

• Gas tankless: 7–8 GPM models — Rinnai RU130iN, Navien NPE-180A2
• Electric tankless: 11–18 kW models — Rheem RTEX-11, EcoSmart ECO 27 for cold climates

Bottom line on 40-gallon water heaters

The 40-gallon water heater is the right pick for 2–3 person households where capacity needs are modest. For long-horizon owners, step up to 50G as cheap demand insurance. For all-electric service, evaluate heat pump at the same capacity for 3x lower operating cost. For sizing-up applications, see 50-gallon or 75-gallon categories.