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The dishwasher mistakes you probably don't even know you're making

Our expert reveals what to avoid – from pre-rinsing to neglecting filters, and more. Plus, should you load cutlery up or down?

half empty dishwasher
Last updated: 03 November 2023

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

But spend some time with CHOICE's dishwasher whiz Ashley Iredale in our testing labs and you'll 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 you might be a novice and you just don't know it.

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

So that you can learn from others' mistakes, Ashley 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 by doing a generous pre-rinse under the tap first. But get ready for a revelation: Ashley says it's unnecessary and might even result in dirtier dishes at the end of the wash.

"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 Ashley.

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 if you pre-rinse your dishes, 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! There's actually 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 40 popular products, cleaning scores ranged from 79% all the way down to 12%. 

Ash Dishwasher two up

Ashley has been testing whitegoods for years.

Interestingly, the test's top cleaner – Aldi Logix Platinum 18 in 1 Dishwashing Tablets – costs just 19 cents a wash, while the second-top scorers (two Finish Powerball Ultimate products) cost up to $1.87 per wash. That's nearly 10 times the price of the Aldi product!

It just shows that choosing wisely makes a huge difference to how much you're splashing out on your dishes over time. 

Choosing wisely makes a huge difference to how much you're splashing out on your dishes over time

Ashley says there are 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."

"Other detergents may not contain rinse aid, meaning they won't wash or dry as well.

"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 expert dishwasher detergent review to see how the product you're currently buying compares with the best. 

3. Not cleaning the filters

You probably know you should do this. But, really, 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.

It's a dirty job that no one likes, but it's important to keep your dishwasher running smoothly

Ashley Iredale, CHOICE dishwasher expert

Despite the ick factor, Ashley 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 says. 

"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 foetid 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."

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 Ashley says down is the only way to go. 

Check out his convincing argument for pointing your cutlery down and send it to your partner or housemates if they're doing it wrong. Then the arguments will be over for good. Probably.

Choice tester Ash Iredale holding knife and fork

Ashley recommends stacking cutlery pointing downwards in your dishwasher.

5. Washing by hand instead of using your dishwasher 

Brace yourself for this truth bomb: washing your dishes by hand in a sink typically uses more water than a dishwasher. Yep, we were shocked too.

Of course, once you've seen the water usage figures for dishwasher vs washing by hand, it all makes sense. 

Saving time, money and water are huge wins, but Ashley 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 asks. 

"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 capacity

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

"Dishwashers are very water-efficient compared with washing by hand in the sink, but to get maximum efficiency you really need to wait till your dishwasher is completely full.

"Running it half-empty is leaving money on the table as far as your energy and water use are 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 get scratched or broken against other items inside. 

"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 Ashley. 

To help you sort the safe items from the not-so-safe, check out our extensive list of what you can and can't put it the dishwasher

woman champagne glass dishwasher

Delicate glassware can get scratched or broken against other items in the wash.

8. Overloading the unit

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. Ashley – who obviously isn't as wild or lazy as some of us – says it's more efficient to stack things sensibly to get a deeper, more dependable wash every time. Make sure water can reach every surface and don't just pile items on top of each other and hope for the best. 

"Badly stacked items will definitely block the jets and detergent from cleaning them," says Ashley. 

"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? Ashley, 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," he says. 

"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, top up the rinse aid reservoir next wash.

10. Shutting the door when it's not in use 

You may not have known this is a no-no, but it makes sense. Ashley advises leaving your dishwasher door slightly ajar between washes for a number of reasons. 

If you shut the door the seals won't dry out, promoting mould growth and foul odours

Ashley Iredale, CHOICE dishwasher expert

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

"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.

Stock images: Getty, unless otherwise stated.