What size water heater for a 4-bedroom house?
Size the house, not the current tenants: a 4-bedroom holds 5 people by the usual planning count (bedrooms plus one), and a full-house morning there runs about 106 gallons of hot water. That takes a 75 gal gas tank, and no single electric tank covers it. If you actually have four people and want that answer instead, open the family of 4 page. A calmer household can step down the table below.
From full house to quiet couple, in gallons
Rows run from every bed filled and everyone showering in the same hour down to one shower. Each row carries one shave and one round of hand dishes (6 gallons of sink use). The full-house row is what this house can demand of the tank; where you actually live on the table is a judgment call the next owner may not share.
| Showers in the hour | Peak demand | Gas tank | Electric tank | Demand, 2.0 GPM heads | Gas | Electric |
|---|---|---|---|---|---|---|
| 1 | 26 gal | 30 gal | 30 gal | 19 gal | 30 gal | 30 gal |
| 2 | 46 gal | 30 gal | 40 gal | 32 gal | 30 gal | 30 gal |
| 3 | 66 gal | 40 gal | 80 gal | 45 gal | 30 gal | 40 gal |
| 4 | 86 gal | 75 gal | none fits | 58 gal | 40 gal | 65 gal |
| 5 | 106 gal | 75 gal | none fits | 71 gal | 50 gal | 80 gal |
Past this size the electric column mostly reads "none fits," and that is real: 5 standard showers in an hour outruns any single residential electric tank. 4-bedroom houses with electric-only service end up at two tanks, an 80-gallon plus discipline, a heat pump unit sized up, or a tankless if the panel and gas line allow.
Four bedrooms usually means two floors, and two floors means pipe
A four-bedroom house is normally two stories, and the second story is what separates this size from the one below it. The heater is in a basement or a garage, the farthest bathroom is upstairs at the opposite corner, and sixty feet of run between them is ordinary. That pipe holds roughly a gallon and a half of cold water at three-quarter inch, so the shower nobody used yesterday runs cold for most of a minute before the 106-gallon question even comes up.
Which is the argument for a recirculation loop, and also the argument against one. A loop puts hot water at the fixture on demand. It also holds a long pipe hot around the clock, and on an electric tank that standing loss is coming out of the same element you were relying on for recovery. Fit one on a timer or an aquastat, never on a switch somebody has to remember.
The other structural answer at four bedrooms is two heaters instead of one bigger one. A 50-gallon unit near the upstairs baths and a 40 near the kitchen and laundry beats a single 75 in the basement on wait time, on pipe loss, and on what happens when one of the two dies on a Sunday. It costs more to install, and it is why plenty of large houses have two water heaters in them rather than one big one.
Questions people ask
What size water heater comes standard in a 4-bedroom house?
Builders typically install a 50-gallon tank in a 4-bedroom house because it is the cheap default, not because anyone ran the numbers. At full occupancy (5 people) that default is undersized for a full-house morning on either fuel.
Should I size for the bedrooms or for who lives here now?
Bedrooms, if the tank will outlive the current household. A tank runs 8 to 12 years; a 4-bedroom house can hold 5 or more for most of that. Sizing to a couple in a 4-bedroom house saves maybe $200 today and gets re-bought by the next full household.
Does a spare bathroom change the size?
Not for a tank. Tank sizing counts gallons in the busiest hour, and an extra bathroom does not shower anybody extra; it just lets two showers happen at once, which is a tankless-sizing (GPM) problem, not a gallons problem.
Is a 4-bedroom house the same as a family of 4?
No. This page plans a 4-bedroom house for five people (bedrooms plus one). A family of 4 is four people and a lighter peak hour, so the tank answer is usually one step smaller. If you know four people live here and will keep living here, use the family page. If you are buying for the house, stay here.