The size and number of spray arm holes can be an indication of the cleaning effectiveness. Smaller holes can create a finer, more vigorous spray for greater scrubbing action. It is important the dishwasher keeps food particles from redepositing on clean dishes. The best way to do so is by filtering the water. A system that filters 100 percent of the water through a very fine mesh is very effective.
Some units have a secondary filter using an even finer mesh, for even better effectiveness.
Internal Food Disposer To improve performance and eliminate the need for prewashing, some dishwashers have a disposer to chop food into tiny particles, which are removed with the drain water. If for some reason the water being supplied to the dishwasher is less than 120 degrees F, select a dishwasher with a thermostat and heating capability to guarantee temperatures are hot enough to remove grease foods. Check to see if the heating function is selectable, so it is used only when needed. Some dispensers allow the amount of rinse aid to be adjusted to meet your water conditions. Dishwashers with a window in the rinse aid dispenser allow the user to easily see when it is time to refill the dispenser.