Dishwasher Detergent Buying Guide

CR’s testers apply a baked-on food mixture to eight ceramic dinner plates and load them into a dishwasher, along with clean plates, bowls, and drinking glasses to fill the machine. After running a normal wash cycle, we use imaging analysis to determine precisely how clean each dish is and whether any water spots are present. Next, we run a set of glass dishware and aluminum tiles through a wash cycle with especially hard water to see how well the detergents can prevent residue. Then we use a spectrophotometer to assess whether any haze or discoloration has formed on the glass and metal.

To help your dishwasher and detergent perform their best, here are a few things to keep in mind.

Skip prerinsing. Most dishwashers have a sensor that checks how dirty the water is. The sensor determines the amount of water and time needed to get the dishes clean. But if you prerinse your dishes and the sensor detects little food, the dishwasher gives the dishes a lighter wash, which can leave bits of food on dishes and glasses. The enzymes in your dishwasher detergent also work best when they have buildup on the dishes to cling to. What you should do, though, is scrape any big chunks of food off dishes and pots before you load them into the dishwasher because those might fall into the tub and reduce your machine’s water flow.

Load correctly. Your owner’s manual will recommend a loading method that works best for your dishwasher. In general, load large items along the sides and back, so they don’t block the water and detergent. Face the dirtier side of dishes toward the center of the machine, and don’t let dishes or utensils nest together. Place items with baked-on food in the bottom rack, face down toward the sprays. Rest glasses upside down on prongs so that they don’t fill with water. Use the top rack for plastic and delicate items that are dishwasher-safe. 

Put the detergent in the right place. As a general rule, you should put your dishwasher detergent in the dispenser unless your dishwasher’s manual specifies otherwise. The dispenser ensures that your detergent is dispensed at the optimal time during the dishwasher’s cleaning cycle. Putting your detergent anywhere else—for instance, tossing it straight into the dishwasher base—can negatively affect your dishwasher’s performance.

Use a rinse aid. If the dishwasher detergent you use doesn’t include a rinse aid, consider using one separately. Rinse aids prevent spotting and improve drying by breaking the bond between the water molecules and dishes, causing water to form sheets and slide off. Many dishwashers have specific rinse-aid dispensers, but if yours doesn’t, you can buy a rinse-aid basket that hangs from the upper rack.

Keep the filter clean. If your dishwasher has a manual-clean filter, it’s important to clean it regularly—that means every couple of months, depending on how often you use your dishwasher. It’s the filter’s job to prevent food debris from redepositing on clean dishes, and bits of food that get stuck there can interfere with that function. Self-cleaning filters don’t require the same maintenance, though if you’re finding food bits on your dishes after a cycle, your filter may have a problem that requires repair.