A 2.5 or 4 gallon tank fits inside a sink cabinet and plugs into an outlet there. It covers hand washing and rinsing at one sink. A 4 gallon tank often costs little more than a 2.5 gallon one, so pick the smaller size only when the cabinet is tight. Check the tank’s width as well as its height: among the 2.5 gallon tanks here, one is under 11 in across and another over 14 in.
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.
Full ranking 10
- Ariston Andris RS 4 Gallon#1 of 10Full review
A 4 gallon plug-in tank at a 2.5 gallon price, with a six-year tank warranty. A strong pick for a kitchen sink.
Amazon $169.99$169.994 gal1,440 WPlug-in - EcoSmart ECO MINI 4#2 of 10Full review
An inexpensive 4 gallon plug-in tank for a kitchen or utility sink. Its warranty is a year shorter than the best small tanks.
Amazon $165.92$165.924 gal1,440 WPlug-in - Camplux ME40 4 Gallon#3 of 10Full review
A narrow 4 gallon plug-in tank that fits where wider tanks don’t. Its tank warranty is shorter than the major brands.
Amazon $209.99$209.994 gal1,440 WPlug-in - Stiebel Eltron SHC 4#4 of 10Full review
A 4 gallon plug-in tank for a kitchen sink or as a booster on a long pipe run, with a six-year tank warranty. Cheaper 4 gallon tanks match its warranty and heat faster.
Amazon $239$2394 gal1,300 WPlug-in - ThermoMate ES400 4 Gallon#5 of 10Full review
A 4 gallon plug-in tank for a kitchen sink. Ariston and EcoSmart sell 4 gallon tanks for less with longer warranties.
Amazon $220.99$220.994 gal1,440 WPlug-in - GE 2.5 Gallon Point of Use#6 of 10Full review
A 2.5 gallon plug-in tank with an eight-year tank and parts warranty, the best-covered small tank here. Good for a single sink where you want it to last.
Amazon $205.26$205.262.5 gal1,500 WPlug-in - Ariston Andris RS 2.5 Gallon#7 of 10Full review
A low-priced 2.5 gallon plug-in tank for a single sink, with a six-year tank warranty. It is the value pick among the small tanks.
Amazon $159.99$159.992.5 gal1,440 WPlug-in - Rheem Mini-Tank 2.5 Gallon#8 of 10Full review
A slim 2.5 gallon plug-in tank from Rheem for one sink. It matches the Ariston on warranty but costs more.
Amazon $218.99$218.992.5 gal1,440 WPlug-in - Stiebel Eltron SHC 2.5#9 of 10Full review
A German-made 2.5 gallon plug-in tank for one bathroom or kitchen sink. It costs more than the imports but carries a six-year tank warranty.
Amazon $212.91$212.912.5 gal1,300 WPlug-in - ThermoMate ES250 2.5 Gallon#10 of 10Full review
A compact 2.5 gallon plug-in tank with a freeze setting, suited to a cabin or garage sink. The warranty is short for the price.
Amazon $199.99$199.992.5 gal1,440 WPlug-in
