30 Gallon Water Heater: How Many People?
One person, or two who do not shower at the same time. Past that, the 40 gallon tank is the honest answer.
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A 30-gallon water heater serves one person comfortably and two at a push. One eight-minute shower uses about 10 gallons of hot water, so 30 gallons of storage covers two showers plus a little washing up before recovery has to catch up. The practical problem is that a 40-gallon tank usually occupies the same alcove and costs little more — a 40-gallon gas unit publishes a 65-gallon first-hour delivery against the 40-odd gallons a 30-gallon tank manages.
Thirty gallons is a real size with a real use case: a studio apartment, a one-bedroom, a mother-in-law unit, a garage shop sink, a cabin with one shower. It is also the size most often bought by accident, because it was what the old one was, and that is how a household of three ends up rationing showers for a decade.
How far 30 gallons actually goes
| Household | Peak-hour demand | Verdict |
|---|---|---|
| One person | About 20 gallons | Comfortable, with headroom for washing up |
| Two people, staggered showers | About 25 gallons | Works, because recovery gets a window |
| Two people, consecutive showers | About 30 gallons | Marginal — the second shower ends cool |
| Two people plus a dishwasher in the same hour | 35 – 40 gallons | Short by about a shower |
| Three people | 50 – 60 gallons | No — this is family-of-three territory |
| One bathroom plus a tub | 40+ gallons for the tub alone | No — a tub fill is the whole tank |
The column that matters is the middle one, and the figure it is built from is simple: an eight-minute shower at 1.8 GPM draws roughly 10 gallons of hot water, because what arrives at the head is blended rather than straight from the tank. Everything else on that table is arithmetic from there.
Why the 40 gallon tank is usually the better buy
- The footprint barely changes. A 40-gallon gas tank runs around 60 to 61 inches tall and 22 inches in diameter. In most alcoves built for a 30, a 40 fits.
- The first-hour rating changes a lot. A 40-gallon gas unit at 36,000 BTU/h publishes a 65-gallon first-hour delivery and 36.4 gallons per hour of recovery. That is not a 10-gallon improvement, it is a 25-gallon one.
- The household changes. A water heater lasts eight to twelve years. A partner, a lodger or a child inside that window turns a correctly sized 30 into an undersized one.
- Resale and rental. A 30-gallon tank in a two-bedroom unit generates complaints from every tenant who ever lives there.
What to look for at this size
- First-hour rating, not capacity. At small sizes the burner or element matters proportionally more, so two 30-gallon tanks can differ noticeably on delivery.
- Recovery rate. Gas at around 36 gallons per hour, electric resistance at around 21 gallons per hour at a 90°F rise. With only 30 gallons stored, recovery is doing more of the work than it does on a 50.
- Height and diameter against the actual alcove, measured, before you decide the 40 will not fit.
- Whether the real problem is a long pipe run. If the complaint is a wait rather than running out, a mini tank at the far fixture fixes it for far less than a new heater.
- An expansion tank. Required by code on a closed system regardless of how small the heater is. Water heater expansion tanks.
Quick picks
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| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Rheem Performance 40 gal gasThe honest small-house gas tank: 36,000 BTU/h, around a 65-gallon first-hour delivery, and a recovery rate of about 36 gallons per hour — which is why a 40-gallon gas tank serves a family that would need a 50-gallon electric. | Smaller gas households | Check price on Amazon No live price feed on this site, so we show none. #ad |
| 2 |  Rheem Performance Platinum 50 gal electricA plain, well-warranted 50-gallon electric tank: a 63 gallon-per-hour first-hour rating, 21 gallons per hour of recovery at a 90°F rise, and a 0.93 UEF. | Straight electric replacement | Check price on Amazon No live price feed on this site, so we show none. #ad |
| 3 |  Bosch Tronic 3000 T ES8 (7.1 gal)The larger mini tank: 7.1 gallons delivered per draw cycle on an ordinary 15 A outlet, which stretches the category from one faucet to a small bathroom. | A sink plus a small basin | Check price on Amazon No live price feed on this site, so we show none. #ad |
What we would buy instead of a 30
Pick 1 — Smaller gas households
Rheem Performance 40 gal gas
The honest small-house gas tank: 36,000 BTU/h, around a 65-gallon first-hour delivery, and a recovery rate of about 36 gallons per hour — which is why a 40-gallon gas tank serves a family that would need a 50-gallon electric.
| Capacity | 40 gallons |
|---|---|
| Input | 36,000 BTU/h |
| First-hour delivery | 65 gallons (Rheem PROG40-36N data); 68 gallons on the Performance retail model |
| Recovery | 36.4 gallons per hour |
| Energy factor | 0.62 (0.58 UEF on the retail Performance model) |
What is good
- Gas recovery means a 40-gallon tank behaves like a much larger electric one
- Cheapest route to a working hot water supply for one or two bathrooms
- Short and tall variants both exist, so it fits awkward spaces
- Parts on the shelf at every supply house in the country
What is not
- Published figures vary between the professional and retail versions of the same nominal unit — read the EnergyGuide label on the box you are buying
- 0.58 to 0.62 energy factor is the low end of current gas tanks
- 40 gallons is genuinely tight above three people
Skip it if: Skip it for a household of four or more with two bathrooms. The first-hour rating is adequate for one bathroom running at a time, and the complaint that follows a too-small tank is always the same: the last shower is cold.
No live price feed on this site, so we show none. #ad
Specifications above from Young Supply listing, Rheem PROG40-36N; Rheem Performance 40 gal retail listing. We have not tested this unit ourselves.
Pick 2 — Straight electric replacement
Rheem Performance Platinum 50 gal electric
A plain, well-warranted 50-gallon electric tank: a 63 gallon-per-hour first-hour rating, 21 gallons per hour of recovery at a 90°F rise, and a 0.93 UEF.
| Capacity | 50 gallons |
|---|---|
| First-hour rating | 63 gallons per hour |
| Recovery | 21 gallons per hour at a 90°F rise |
| Efficiency | 0.93 UEF |
| Voltage | 240 V |
What is good
- Publishes recovery at a stated temperature rise, which most retail listings do not
- 0.93 UEF is at the top of what a resistance tank can do
- Drop-in replacement dimensions for the previous generation
- Available in short and tall variants
What is not
- 21 gallons per hour of recovery is a third of what a gas tank does
- No leak detection on this model
- Resistance heating is the most expensive way to make hot water in most of the country
Skip it if: Skip it if you have 7 feet of headroom and an unconditioned space to put it in. A heat pump model in that spot uses roughly a third of the electricity for the same hot water, and the payback is measured in a few years, not decades.
No live price feed on this site, so we show none. #ad
Specifications above from Home Depot specification sheet, Rheem Performance Platinum electric (PDF). We have not tested this unit ourselves.
Pick 3 — A sink plus a small basin
Bosch Tronic 3000 T ES8 (7.1 gal)
The larger mini tank: 7.1 gallons delivered per draw cycle on an ordinary 15 A outlet, which stretches the category from one faucet to a small bathroom.
| Capacity | 7.1 gallons |
|---|---|
| Voltage | 120 V |
| Power | 1,440 W |
| Circuit | Standard 120 V 15 A outlet |
| Delivery | Up to 7.1 gallons per draw cycle before recovery |
| Tank | Glass-lined, foam insulated |
What is good
- Nearly double the ES4's storage on the same 15 A outlet
- 7.1 gallons covers washing up plus a basin without recovering
- No wiring work needed
- Same simple serviceable design as the smaller unit
What is not
- Takes more cabinet space than the 4-gallon version
- Same 1,440 W recovery, so it refills no faster — it just holds more
- Larger standby loss than the ES4
Skip it if: Skip it if the cabinet under the sink is shallow. The ES8 is noticeably bigger than the ES4, and a mini tank that does not fit the cabinet ends up on the floor beside it.
No live price feed on this site, so we show none. #ad
Specifications above from Rural Energy listing, Bosch Tronic 3000T ES8. We have not tested this unit ourselves.
The picks explained
We do not carry a 30-gallon model in our registry, and we are not going to invent one to fill the slot. What we carry are the three appliances a 30-gallon shopper should actually compare against: the 40-gallon gas tank that fits the same space and delivers 25 more gallons in the first hour, the 50-gallon electric tank that is the correct electric size for anything beyond one person, and the 7.1-gallon mini tank that solves the case where the real problem is one remote fixture rather than the whole house.
If your situation genuinely is a single occupant in a space that will not take a 40, buy the smallest tank from a brand whose parts you can get locally and fit an expansion tank and a pan with it. The appliance matters less at this size than the install does.
30 gallons on gas versus electric
| Gas | Electric resistance | |
|---|---|---|
| Recovery | About 36 gallons per hour at 36,000 BTU/h | About 21 gallons per hour at a 90°F rise |
| Effect on a small tank | Recovery partly compensates for low storage | Storage is almost all you get inside the peak |
| Practical ceiling | Two people, staggered | One person |
| Needs | Combustion air and a flue | A 240 V circuit |
| Running cost | Usually lower where gas is available | Higher, unless rates are unusual |
That table is the reason a 30-gallon electric tank is the single most commonly undersized water heater sold. With 21 gallons an hour of recovery and 30 gallons of storage, there is no mechanism to bail you out inside a peak. Gas vs electric water heaters covers the wider version of this decision.
What goes in with it
A water heater is a system, not a box. These are the parts that go in with it, and the ones people discover they need halfway through the job.
- Expansion tank
Required by code on a closed system, which is most homes with a pressure-reducing valve.
- Drain pan
Cheap insurance anywhere the tank sits above something you care about.
- Anode rod
The part that decides when the tank leaks. Replacing it is the highest-value hour of maintenance there is.