The Truth about Dish Washers

The Myth of Dishwashers

A lot of people think of dish washers as being a type of sterilizing system.  The heat, water and detergent will kill all bacteria and leave all surfaces surgically clean and are always better than hand washing.  Unfortunately heat sterilization - killing of bacteria by applying near boiling temperature or steam above boiling - is not part of the dish washing process.   The temperatures inside the dishwasher never achieve the high temperatures needed to achieve this.

Chemical sterilization also does not take place.  The soaps used in a dishwasher are no more caustic than your counter top dish soap.

Making Dishes Clean

There are two things that must be done to make a dish clean:

• Food substances to be completely removed.  This especially means any oils, greases or sugars.
• Surfaces must be dried and kept that way for storage.

If you leave food, or worse, food + moisture on an eating utensil it will be ripe for bacterial growth, no matter how good your dishwasher or detergent brand may be.

The Three Pillars of Dish Cleaning

Abrasion - Removal of food and other particles by physical means (a sponge, scouring pad or jets of water all count).  This process assists and is assisted by dilution.

Dilution - Removal of grease, oil and any remaining food particulates by dissolving them into the water/soap mix which is then flushed and rinsed away.  This is the main reason for using very hot water.  The detergent's main job is also here.  The soapy bubbles we associate with soaps also demonstrate emulsification, that is, trapping oils in bubbles so they stay dissolved into the water instead of being redeposited on the dishes.. 

Desiccation - Drying the dishes completely.  All life needs moisture.  Removing this moisture quickly after washing will prevent disease.   If a dish is not dry, it's not really clean.

At home, if you achieve all three of these steps routinely then you will have clean and safe dishes.

While institutions like hospitals and restaurants take things further they still have to build upon these three basic steps, as opposed to replace them with others.