Almost all new washers have programmable controls that allow the cycle time and temperatures to be precisely controlled for wash quality. The programming usually is completed by the laundry chemical representative. Programming is where green savings begin. If a cycle uses a prewash, there will be 15-25% more water used. The only time a prewash is required is for heavy soils. Most programs do not require prewash. Bleach bath is another programming function that can determine water consumption. Many chemical companies program an extra hot water fill for bleaching.
This step could require 15% more water. Since it is usually hot water, it also will require more energy.
Washer programming is the biggest variable in controlling water consumption. It is also a contributor to determining energy consumption. The human interface with programming directly impacts water and energy savings.