An 18 gallon plug-in tank with an eight-year warranty, for a small apartment, cabin or a washer far from the main heater. The best large pick.
Amazon $296.65
A 20 gallon, 120 V tank that fits under a counter, for a small apartment, cabin or in-law suite, with six years on parts and tank.
- 20 galTank
- 1,500 WElement
- 6 yearsTank warranty
Price checked November 9, 2026. As an Amazon Associate we earn from qualifying purchases.
- The most stored hot water here, enough for a short shower
- Six-year warranty on parts and tank
- Only 25.5 in tall, so it fits under a counter
- Floor-standing; no wall bracket
- Recovers about 7 gallons an hour at a 90 °F rise, so a drained tank takes hours to refill with hot water
The Ariston POU family
Every Ariston POU model we rank, smallest first. Ratings compare each against its own size.
| Model | Tank | Rating | Price |
|---|---|---|---|
| Ariston POU 6 Gallon | 6 gal | 2.8/5 | $283.87 |
| Ariston POU 12 Gallon | 12 gal | 2.9/5 | $313 |
| Ariston POU 20 Gallon (this one) | 20 gal | 3.7/5 | $351.50 |
How it scores
The rating comes from 5 measured or published factors, each scored 0-100 against fixed reference points for its size. How we rank explains each one.
Specifications
| Model number | ARI POU-20 120V 1500W |
|---|---|
| Heating | |
| Tank capacity | 20 gal |
| Element | 1,500 W |
| Voltage | 120 V |
| Current | 12.5 A |
| Recovery (maker figure) | 7 gal/hr at 90 °F rise |
| Thermostat range | 90 to 160 °F |
| Price per gallon | $17.57 |
| Installation | |
| Dimensions (H x W x D) | 25.5 x 18.2 x 18.2 in |
| Water connections | 3/4" NPT |
| Relief valve included | Yes |
| Wall bracket included | No |
| Warranty | |
| Tank | 6 years |
| Parts | 6 years |
Alternatives in this size
A cheap 18 gallon tank for a shop, barn or utility room. With no published warranty, the GE 18 gallon is the safer buy for a home.
Amazon $219.90A 12 gallon tank for a bathroom or kitchenette, with six years on parts and tank. Larger tanks cost little more.
Amazon $313Compare
Compare the Ariston POU 20 Gallon with any other mini tank water heater →
More from Ariston: every Ariston product ranked.