Josephine Cochrane, an American socialite, was widowed and left with mounting debts in 1883. However, she had an idea that would turn her fortunes around. Years of hosting lavish dinner parties and watching her dishware get chipped during handwashing convinced her that the world needed a better way to clean dishes. So, she poured the little money she had left into building a prototype, eventually showcasing her dishwashing contraption at the Chicago World's Fair. This was the first step towards the modern dishwasher, whose basic design remains remarkably similar to Cochrane's.
When you press start on a dishwasher, it fills a small basin with water that's heated up to 60°C. Then the pre-wash cycle begins. A circulation pump sends high-pressure water up into spray arms, where it shoots out of angled nozzles, propelling the arms to spin. The water recollects in the basin, where, in most modern models, a turbidity sensor measures the water's dirtiness by seeing how much light passes through it. The dishwasher then adjusts the wash time and water temperature accordingly and transitions to the wash cycle.
The main ingredient in all three forms of detergent - liquid, powder, and pods - is the surfactant. These special dual-ended molecules remove food residues by latching onto them with one end and pulling towards the water with the other. You'll also find surfactants in regular dish soap, but detergents go further. They often contain enzymes that break down food into smaller pieces that surfactants can easily tug away, and bleach, which disinfects and removes stains.
So, which detergent form is best? Liquid detergent can only contain bleach or enzymes, since bleach breaks down enzymes in liquid form. Powder detergents solve this problem by coating powdered enzymes with a protective wax, allowing them to work alongside powdered bleach. But even more effective are dishwasher pods that separate components using a plastic film. Though, pods may have environmental impacts - some studies claim the plastic biodegrades in a couple of months, while others find it persists for much longer.
How you treat your dishwasher, and the dishes you put in, can also affect performance. A dirty dishwasher or filter can trick the turbidity sensor into thinking dishes are dirtier than they are, prompting an unnecessarily long wash cycle. And while it might seem counterintuitive, rinsing dishes beforehand can also cause problems. If dishes are well rinsed, the turbidity sensor will detect minimal grime and trigger a short wash cycle, which may not be enough to break down any stubborn stuck-on crust.
Further, the enzymes in detergent are designed to latch onto food residue, so the best practice is to simply scrape your dishes before loading. What's more, by letting the dishwasher do all the work, you'll also save water. Dishwashers recycle water during the wash cycle, so they only use 3 to 5 gallons. That's equivalent to running a kitchen sink for up to 2.5 minutes. So if you think handwashing your dishes might take longer than that, it might be worth just running a load.
Of course, there are reasons to not throw in the towel on handwashing altogether. Since dishwashers use very hot water, they can warp wooden items and certain plastics, damaging seals in travel mugs or storage containers. Sharp knives can also be dulled by detergents, or they can even damage the dishwasher itself. And there's also an energy consideration. On average, a standard dishwasher cycle uses about the same amount of energy as leaving your TV on for 12 hours. Clearly, there are situations when handwashing makes more sense. But if you're faced with a dinner party's worth of dishes, a dishwasher can be a welcome reprieve.
