The statement that pre-washing dishes before placing them in the dishwasher is a waste of water and money, and may not allow the appliance to clean the dishes properly, is generally supported by many dishwasher manufacturers and experts.
Here's the reasoning behind this perspective:
Water Waste: Dishwashers are designed to handle food particles and debris on dishes efficiently. Pre-washing dishes can lead to unnecessary water consumption, as the dishwasher will still go through its regular cycle, using additional water even if the dishes appear to be clean after pre-washing.
Energy Consumption: Running the dishwasher for a shorter duration without pre-washing can save energy, as modern dishwashers are designed to be more water and energy-efficient.
Detergent Efficiency: Pre-washing can remove some of the food particles that dishwasher detergents are meant to target. This can lead to less effective cleaning as dishwasher detergents are formulated to break down food residues.
Hydraulic Pressure: Dishwashers rely on the hydraulic pressure created by dirty dishes to effectively clean the entire load. Without some food particles, the dishwasher may not achieve optimal cleaning, especially for items on the upper rack.
Savings: Not pre-washing can save money on water bills and dishwasher detergent since you'll be using fewer resources overall.
However, there are exceptions to this rule. Extremely large or hardened food particles may clog the dishwasher's filters or spray arms, so it's a good idea to scrape off excess food before loading the dishwasher. Additionally, dishes with certain types of burnt-on or dried food may benefit from a light rinse or soak before being placed in the dishwasher.
In conclusion, pre-washing dishes before placing them in the dishwasher is generally considered unnecessary and can be a waste of water and money. It's more eco-friendly and cost-effective to let the dishwasher do its job and handle the cleaning efficiently. However, some basic scraping or soaking of heavily soiled dishes can still be useful in certain cases.