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 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 the time needed to clean the dishes. 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 large chunks of food off dishes and pots before loading them into the dishwasher because they may 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. 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. While some detergents contain rinse aid as one of their additives, experts recommend using a separate rinse aid for maximum effect if you want your dishes to be drier and have fewer water spots.

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.

Do dishwasher detergents sanitize dishes? The answer is no. The primary function of dishwasher detergents is to remove food residue, grease, and stains, not sanitization, according to Aleksandra Kruszewska, senior manager of research and development for the dishwashing brand Finish.

The heat inside your dishwasher actually plays the most important role in sanitizing dishes. If you want your dishes sanitized, select the sanitization cycle on your dishwasher, which will raise the water temperature inside the dishwasher to at least 180° F, says Morgan Eberhand, principal scientist with Cascade.

What’s the difference between a detergent labeled as "3-in-1" and a "4-in-1"? These terms refer to the components within a detergent that offer different functions, such as removing stains or preventing discoloration and dullness on dishes, says Kruszewska.

However, there are no industry standards for the specific ingredients contained in a detergent when it’s labeled as "3-in-1" or "4-in-1," and the composition varies by brand. For clarity, it’s best to read the label of the detergent you’re considering buying to understand its components or the effects of the formula, says Tim Fowler, head of research and development at Seventh Generation.

How can I ensure that my dishwasher pods or tablets dissolve completely? If you find that your pod often ends up partially dissolved or not dissolved at all after a cycle, here’s what to do: First, make sure your hands and the detergent compartment inside the dishwasher are dry before you load the pod into the machine. Because the film on the dishwasher pod is designed to dissolve on contact with water, even exposure to a small amount of moisture can dissolve the film and cause the pod to stick to the compartment and not be dispensed properly, says Eberhand.

When loading the dishwasher, check that the detergent compartment isn’t blocked by any large dishes. If the detergent compartment door can’t open fully during the cycle or the detergent isn’t able to be released, the pod won’t dissolve.

If you’re using the short cycle on your dishwasher, be aware that different forms of single-dose units have different rates of dissolution. Hard-pressed powder tablets take longer and may not fully dissolve by the end of a shorter cycle, whereas dishwasher pods encased in highly soluble PVA film usually will dissolve completely, even in a short wash, Eberhand says.