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10 common dishwasher mistakes: Are you making them?

Our expert reveals the easy errors to avoid, from pre-rinsing and poor detergents to neglecting filters and more.

full dishwasher grimace emoji
Last updated: 04 February 2021

Using a dishwasher is pretty easy, right? You load it up, lob in a tablet, hit start and hey presto, the dishes are done. 

Or so I thought before I started working with CHOICE's dishwasher wiz, Ashley Iredale. Spend time with him in our testing labs and you quickly learn there's a big gap between beginner and boss level when it comes to getting the best clean from your machine. Turns out I've been a novice for decades.

In contrast, Ash and our lab team have been testing and reviewing dishwashers for years. Along the way, they've regularly uncovered the best models, exposed serious shockers and even cooked dinner in a dishwasher (honey soy salmon!).

Ash Dishwasher two up

Ashley has been testing whitegoods for years.

So you can learn from my mistakes, Ash outlines the everyday errors to avoid and shares his invaluable advice for saving time, money and water.

1. Pre-rinsing dirty dishes

We're all guilty of giving our dishwasher a helping hand with a generous pre-rinse under the tap first. But get ready for a revelation - Ash says it's unnecessary and might even result in dirtier dishes at the end of the wash. Mind blown.

"Not only does pre-rinsing push your water consumption way up, it can actually trick your dishwasher into thinking your plates are cleaner than they are," explains Ash.

Pre-rinsing can actually trick your dishwasher into thinking your plates are cleaner than they are

Ashley Iredale, CHOICE dishwasher expert

"Dishwashers use what's called a turbidity sensor to measure the level of soil in the first rinse cycle, so it'll use less power and things might actually come out dirtier. You're better off scraping solids into the bin and letting your machine do the rest."

dirty dishes in dishwasher

Remove solids from dishes but don't pre-rinse - let the machine do the work.

2. Using poor detergents

All products clean the same, right? Wrong! If there's one thing I learnt early from Ash and his dishwashing dons is that there's a great divide between good detergents and bad ones. And it's hardly as simple as pricey ones wash well and cheaper ones don't.

In our lab tests of 29 popular products, cleaning scores ranged from 78% all the way down to 43%. Interestingly, the test's two top cleaners - Finish Powerball and Earth Choice tablets - cost $1 and 39 cents a wash respectively, which makes a huge difference over time. 

Ash says there's also other downsides to using bad detergents. "Not only do you run the risk of your plates coming out dirty, some cheap and nasty detergents contain harsh abrasive agents that can actually dull or wear away your delicate glassware fairly rapidly," he explains.

"Other detergents may not contain rinse aid, meaning they won't wash or dry as well, so choose wisely. Luckily, our tests have shown you don't need to pay top dollar to get a great wash, although we generally find tablets do perform better than their cheaper powder counterparts."

Check out our full review to compare the best detergents and your current one.

3. Not cleaning the filters

To be honest, I know I should do this – I just don't because filters are festy. Who wants to stick their hand into a slimy hellmouth of gunk, meat muck and soggy beans? Same goes for trying to pull debris out of the spray arms' tiny holes – it's both disgusting and difficult. 

Who wants to stick their hand into a slimy hellmouth of gunk, meat muck and soggy beans?

Despite the ick factor, Ash says it's vital to take the plunge at least once a month to keep your machine clean and unclogged.

"It's a dirty job that no one likes, but it's important to keep your dishwasher running smoothly and reduce the likelihood of food particles being redeposited on plates," he advises. 

"A dirty filter left for too long can also cause bad blockages. Cleaning it may be unpleasant, but it's nowhere near as stomach-turning as having to reach into a black pool of fetid wash water in the bottom of your unit to clear a blockage. Experience that once and I guarantee you'll make filter cleaning a very regular chore indeed."

Okay, I'm convinced. Prep the biohazard suit, I'm going in.

4. Stacking your cutlery the wrong way

It's the domestic dispute that's raged since the dawn of the dishwasher – should your cutlery point up or down in the basket? Some argue it's up, up and away for a better wash, while their opponents play it safe and go down all the time. 

There are pros and cons for each side, but Ash says down is the only way to go. Check out his convincing argument and send it to your partner or housemates if they're doing it wrong. Then the arguments will be over for good, right?

Choice tester Ash Iredale holding knife and fork

Ash recommends stacking cutlery down in your dishwasher.

5. Handwashing instead of using your dishwater 

Brace yourself for this truth bomb: handwashing in a sink typically uses more water than a dishwasher. I know, I know, I was shocked too. Still am. Of course, once you read Ash's water usage article, it makes sense but it's still a doozie. 

Saving time, money and water are huge wins, but Ash also points out other reasons to use your dishwasher regularly. 

Handwashing in a sink typically uses more water than a dishwasher

"Why would you waste the time, energy, water and purchase price of your dishwasher by doing its job for it," he argues. "Plus, dishwashers like to be run. If you leave them for too long, their seals can dry out and harden, and you may even get an insect infestation that can cause your unit to break down. Cockroaches love electrical circuits for some reason."

6. Not filling it to full capacity

Of course, for the last point to be true, you need to load up your machine fully to get your money's worth. 

Ash explains: "Dishwashers are very water efficient compared to hand washing, but to get maximum efficiency you really need to wait til it's completely full."

"Running it half-empty is leaving money on the table as far as your energy and water use is concerned. Also, a full dishwasher will have better drying performance due to the greater thermal mass of its contents."

7. Washing non-dishwasher safe items

We've all been there. You're in a rush so you pop that wooden chopping board or those posh wine glasses into the dishwasher. You know it should be hand-washed but life's too short and there's too much to do. 

You may save some time then and there but the bad news is you'll probably need a new board and glasses down the track. Wood can fade and split in hot water, and delicate stemware can scratch or break against other items inside. That's the price for living life on the edge. 

"Your dishwasher's a pretty harsh environment with lots of water, heat, and high alkalinity, and it can do a lot of damage to non-dishwasher safe items," says Ash. To help you sort the safe items from the not-so-safe, check out our extensive dishwasher master list

woman champagne glass dishwasher

Delicate glassware can scratch or break against other items in the wash.

8. Overloading the unit

I know this one's naughty, but who doesn't like playing the dishwasher Tetris challenge where you cram in as much as possible? You could win, you could lose, but you'll never know if you don't play the game.

Or not. Ash – who obviously isn't as wild or lazy as me – says it's more efficient to stack things sensibly to get a deeper, more dependable wash every time. Ensure water can reach every surface and don't just pile items on top of each other and pray. 

"Badly stacked items will definitely block the jets and detergent from cleaning them," he explains. "Sure you can always squeeze more in, but any time you save will be spent later sorting clean and still-dirty dishes, or picking crusty bits off your cutlery."

9. Not using rinse aid

Turns out rinse aid isn't just a second soap that comes in a smaller, more expensive bottle. Who knew?! Well, Ash apparently, and he explains it's key for cleaner, drier dishes.

"Rinse aid is a surfactant that contributes to cleaning, but also reduces the surface tension of water, so water will more readily sheet off your plates rather than forming water drops. This aids drying performance and also avoids spotting on your glassware."

Luckily for us, many detergents already contain rinse aid, but if yours doesn't, try topping up the rinse aid reservoir next wash.

10. Shutting the door when not in use 

I never knew this was a sin, but it makes sense once you know. Ash advises leaving your dishwasher door slightly ajar between washes for a number of reasons. 

"Like your washing machine, your dishwasher is a wet environment and its rubber door seals are a little delicate," says Ash. 

"If you shut the door tightly, your seals won't get a chance to dry out, promoting mould growth and leaving you with foul odours. Plus, your seals could become crushed over time and not seal as well. Leaving your unit ajar helps them retain the shape."

We care about accuracy. See something that's not quite right in this article? Let us know or read more about fact-checking at CHOICE