Water Level Settings
A basic washing machine has three settings — low, medium and high — for water level. The user chooses the setting based on the size of the load being washed. More expensive models will have four or more settings, or even sensors that automatically the amount of water used to the optimal level. Most front-loaders have this option.
Using just enough water to cover the clothing is considered to be the most effective and efficient. If your wash loads are always the same size and you never need to adjust the setting, water level may not concern you.
Water Temperature Settings
Again, a basic washing machine will offer just three temperature choices: hot, warm and cold. But if you find yourself shrinking or fading clothing on a regular basis, it is worth looking for a model with a few more temperature settings or with automatic temperature control. The automatic adjustment feature not only will change the wash and rinse temperature to best clean your clothes, but ensure that in cold weather the cold water isn't actually freezing and the warm water isn't actually lukewarm.
To achieve the high water temperatures necessary for eliminating the worst germs, look for washers with a temperature boost or a sanitize cycle. For example, the Asthma and Allergy Foundation of America recommends washing bedding in water at least 130 degrees Fahrenheit to kill dust mites, a common source of allergies.