Ariston POU 20 Gallon
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.
Amazon $351.50$351.50
The Ariston POU 20 Gallon is the better mini tank water heater overall, rated 3.7 to 2.4. The Ariston POU 20 Gallon leads on value and tank size. The Ariston POU 20 Gallon costs $48.20 less ($351.50 vs $399.70).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
ThermoMate ES2000 18 Gallon
An 18 gallon hardwired tank for a shower or washer. The GE 18 gallon costs less, plugs in and carries an eight-year warranty.
Amazon $399.70$399.70
Which should you buy?
- Choose the Ariston POU 20 Gallon for value ($17.57 per gallon ($351.50, 20 gal) vs $22.21 per gallon ($399.70, 18 gal)) and tank size (20 gal tank vs 18 gal tank).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every 12 to 20 gallon mini tank water heater; a clear win is highlighted. How we rank explains each one.
| Factor weight | Ariston POU 20 Gallon | ThermoMate ES2000 18 Gallon |
|---|---|---|
| Overall rating | 3.7/5 | 2.4/5 |
| Value 30% | 58 $17.57 per gallon ($351.50, 20 gal) | 33 $22.21 per gallon ($399.70, 18 gal) |
| Warranty 30% | 83 6-year tank, 6-year parts | 0 warranty not published, scored as none |
| Heating power 15% | 29 1,500 W element | 29 1,500 W element |
| Features 15% | 35 relief valve included | 35 relief valve included |
| Tank size 10% | 100 20 gal tank | 75 18 gal tank |
Specifications
| Ariston POU 20 Gallon | ThermoMate ES2000 18 Gallon | |
|---|---|---|
| Heating | ||
| Tank capacity | 20 gal | 18 gal |
| Element | 1,500 W | 1,500 W |
| Voltage | 120 V | 120 V |
| Current | 12.5 A | - |
| Electrical connection | - | Hardwired |
| Recovery (maker figure) | 7 gal/hr at 90 °F rise | - |
| Thermostat range | 90 to 160 °F | 90 to 150 °F |
| Price per gallon | $17.57 | $22.21 |
| Installation | ||
| Dimensions (H x W x D) | 25.5 x 18.2 x 18.2 in | 25.8 x 19.2 x 19.2 in |
| Weight | - | 56 lb |
| Water connections | 3/4" NPT | 3/4" NPT |
| Relief valve included | Yes | Yes |
| Wall bracket included | No | - |
| Warranty | ||
| Tank | 6 years | - |
| Parts | 6 years | - |