What is a countertop dishwasher?
A countertop dishwasher sits on your countertop rather than being built-in. Generally, these units are substantially smaller than "normal" dishwashers, both in exterior dimensions and interior capacity. They have a drain hose that can drain to your sink drain and a quick connect adapter to accept water from standard sink faucets.

Why should I get a countertop?
Countertops are great for situations where you need a dishwasher, but you cannot fit a built-in or portable dishwasher, and you have a little counter space to spare. Also, if you have a small family that has trouble filling a full-size dishwasher, a countertop may be just the ticket.

Does a countertop produce different results than a normal dishwasher?
Countertops usually clean just as well as full-size models. If you are interested in the best cleaning performance you can get, invest in a model with two spray arms, which will spray water at the dishes from the top and the bottom of the machine. This criss-crossing of water jets will clean better than models that only use a single spray arm.

As you might expect, countertops use less water and detergent than their full-sized rivals, and they often have significantly shorter cycle times. However, most models of countertop on the market lack a true dry cycle.

Can I install my countertop unit permanently?
Some models of countertop can be installed permanently, but no models are specifically designed for permanent installation. If a model can be installed permanently, you may have to alter the unit and do some custom installation. If you go this route please be aware that you may be voiding the dishwasher's warranty.

Can I put this unit under my sink, draining to my garbage disposal?
Most countertops can but put under a sink, to drain to the garbage disposal. However, make sure the unit you buy comes with an internal pump to expel the drainage water high enough to drain into the garbage disposal.

What factors should I consider when shopping for a countertop?

Dimensions
Make a careful note of the exact dimensions you can use to accommodate a countertop. Take special note of the distance between the top of your counter and the bottom of your cabinet.

Two spray arms or one
Two spray arms will clean better, but models with one spray arm are generally less expensive. Please note that models with one spray arm will clean well enough to remove all but the most stubborn, dried or caked-on debris.

Capacity
Most models of countertop will accept up to 4 place settings. Some models will accept up to 8 place settings. Do you need the extra capacity?

The interior composition
Countertops with stainless steel interiors will be more durable and should last longer than models with plastic interiors.

Dry cycle
If it is important to you to have a dry cycle, look for a model that includes this feature.

Pump
If the water draining out of the countertop needs to go above the level of the dishwasher (as it would if you placed the unit below the level of the drain) you need a model with a pump.

Water heater
Most countertops come with water heaters of varying power. Those countertops that have water heaters also usually have two or more settings to vary the power of the heater.

Cycle time
Countertops generally have shorter cycles than full size dishwashers, but the cycle times may vary between machines.

Number of different cycles
Different models of countertop vary in the number of cycles they offer.

Energy and water efficiency
Check the water and energy usage of the countertops to find one that meets your needs.

Ability to be built-in
If you need to build a countertop in, make sure to get a model that can be used in this manner.