Dishwashers, especially newer ones, are pretty great. Instead of standing in front of a sink scrubbing a mountain of dirty dishes for what feels like an eternity, we can just fill up the machine, then set it and forget it for an hour or two. They make our lives so much easier—assuming the dishes you unload are actually spotless. This isn’t always the case though, and sometimes we (unknowingly!) make a few mistakes that could be compromising the dishwasher’s performance, leading to pesky white spots or a lingering film.
To help us get to the bottom of what could be causing less-than-sparkly dinnerware, we turned to Morgan Eberhard, senior scientist at Cascade, and Brandon Pleshek, the cleaning expert and third-generation janitor (yep, you heard that right) behind the viral TikTok account, CleanThatUp. Now here’s how we could be doing a better job of helping the dishwasher do its job.
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Spotting vs. Cloudiness
- What causes spotting: It’s essentially calcium and magnesium left behind by your water, confirms Eberhard. If you know you have hard water, which is high in those minerals, a rinse aid will help significantly by lowering the surface tension of your water. “The ‘sheeting action’ of the rinse aid helps keep water from clinging to your dishes so the drops don’t hang around leaving residue,” Eberhard adds.
- What causes cloudiness: The white film left on dishes may be another sign of hard water, says Eberhard. To check, she recommends removing the film with vinegar or by hand-washing the glass with warm water and dish soap. If the film comes off, then you’re dealing with hard water problems, which are usually easy to fix with rinse aids. If not, then your glasses might be etched, which means they have lots of tiny little scratches.
A Clogged or Super Dirty Dishwasher Filter
This might be hindering your machine’s performance, resulting in splotchy glasses, Pleshek says. If the filter is not cleaned monthly with hot, soapy water and a bottle brush, your dishwasher will just re-circulate any dirt, grime, and mineral deposits, potentially spraying it all back onto your dishes. In fact, you really should be cleaning the entire dishwasher interior on a monthly basis by popping a dishwasher cleaning pac into the detergent compartment and running an empty cycle to help reduce build-up. Deeper cleanings can take place every few months.
You’re Not Positioning Your Glasses Correctly
This is where your dishwasher loading techniques might come under scrutiny. Eberhard suggests angling cups and glasses on the top rack to prevent water from collecting after the wash cycle is complete. She also recommends stacking cups between the top rack’s tines, not over them—otherwise wet contact points could result in spots when they dry.
The Water Temperature Is Too Low
Two things could be happening as a result of cool water. The first is that it takes much longer for water to evaporate when it’s not super hot, making it easy for soap or mineral deposits to form on dinnerware. The other thing that could be happening is that the water isn’t hot enough to fully dissolve the detergents, which could lead to speckling or gritty residues. Aim for a minimum of 120°F.
You’re Pre-Rinsing
It turns out this could actually result in dirtier-looking dishes. “When there is no food on the dishes to break down nor any hard water minerals present because of soft water, it can lead to the removal of metal ions in glassware, causing etching to occur,” Eberhard says. Lots of chemistry! So skip the rinse (and save water) by scraping off as much food as possible into a trash can or compost bin, she recommends. Those streaks of food soils on plates will give the detergent a job to do!
The Water Temperature Is Too High
Speckling might be caused by low temps, but a white cast might be due to super high ones. Etching can occur when the water temperature goes over 140 degrees so maybe refrain from hitting the sanitize cycle too often, which is at least 150 degrees. Basically, the sweet spot is between 120 degrees and 140 degrees!
You’re Not Using the Right Amount of Detergent
According to Pleshek, too much could lead to build-up that isn’t getting rinsed off, especially if you’re not running full loads. (You don’t need the same amount of gel for a half load of dishes as you would a full load!) This can be fixed by hand-washing with dish soap or using vinegar to cut through the residue. But the haziness resulting from too much detergent can’t always be undone—if you have soft water and are in the habit of over-pouring, then you have the recipe for permanent etching.
“This milky film-like surface cannot be removed because metal ions have been removed from the surface of the glass by silica compounds,” according to GE Appliances. (Conversely, if you have hard water, you might actually need a tiny bit more detergent!) Soft water folks can rest assured that their dishes will still get clean though: A dishwasher study in 2011 found that softened water using almost 30% less detergent cleans as well as water with greater hardness levels.
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