While some modern dishwashers are more advanced and can handle lightly soiled dishes, it's generally recommended to rinse dishes before placing them in the dishwasher for several reasons:
Food residue can become hardened: If you leave food particles on dishes for an extended period, they can dry and harden, making it more challenging for the dishwasher to remove them effectively. This could result in leftover food stuck to your dishes after the cycle.
Preventing bad odors: Leaving food scraps on dishes can lead to unpleasant odors in the dishwasher and even in your kitchen, especially if you don't run the dishwasher immediately after loading it.
Avoiding clogs and damage: Large food particles that are not rinsed off might get caught in the dishwasher's filters or spray arms, potentially leading to clogs and reducing the dishwasher's efficiency. In extreme cases, it could cause damage to the appliance.
Hygiene concerns: Pre-rinsing helps maintain a more hygienic environment in the dishwasher. If food debris remains on dishes for an extended period, it can create an environment where bacteria and germs can thrive.
Energy and water efficiency: Rinsing dishes with hot water before placing them in the dishwasher can use more energy and water than necessary, as the dishwasher will still need to run a full cycle. Pre-rinsing also defeats some of the water-saving benefits of using a dishwasher.
However, it's essential to strike a balance when pre-rinsing dishes. You don't need to scrub the dishes completely clean; a simple rinse to remove most of the visible food debris should be sufficient. Modern dishwashers with food sensors and powerful cleaning capabilities are designed to handle a certain level of food residue, but it's always best to give them a little help by rinsing off excess food.