Why doesn’t my dishwasher wash my dishes?

July 3rd, 2015

Appliance Hack Appliance Talk Dishwashers

Is there anything more frustrating than an appliance that doesn’t do its job properly?

“Scrub faster, troops!” (source: Jim Bauer on Flickr)

There are a number of possible reasons for your dishwasher to do a shoddy job, and fortunately, there are also a number of solutions to these problems.  And most of these solutions don’t require too much time, effort or expense, either…

Change your detergent

The reason there are so many different types of dishwasher detergent available isn’t (just) marketing – it’s also because not all dishwasher detergents do the same job.  Some have been made to better clean delicate glassware, others to tackle heavily-soiled pots and pans, and others to manage a lot of grease.  Make sure you’re using the right kind of detergent to suit your load.

source: Elke Wetzig on Wikimedia Commons

Take care when it comes to your dishwasher’s detergent dosage – using too much detergent or too little can result in a less than satisfactory clean.  We recommend sticking to dishwasher tablets (even if they can be a bit more expensive) so you’ll always get a reliably-measured dosage.

The same principles apply when using rinse-aid.  Using no rinse aid or not enough can leave you with water spots or a film over your dishes, while using too much can leave streaky residue behind.  Always check your dosage.

Also, while it might be more economical to buy a gigantic box of detergent and stretch out its use over time, detergent does have a shelf life and will eventually expire as the enzymes start to die off.  This is a Bad Thing, as it’s the enzymes that do the heavy lifting when it comes to cleaning your dishes.  Buy a big bulk pack of detergent if you plan to do a lot of dishwasher loads, not to stretch out time between shopping trips.

Loading the dishwasher – Avoid shadowing

Remember how in school photos the tall kids would always stand at the back and the short kids at the front, so the shorties wouldn’t get eclipsed by their taller comrades?

The same principle applies when stacking dishes in the dishwasher – keep the tall dishes further away from the spray sources and small dishes closer.  A tall dish positioned close to the spray arm will likely block the water from reaching smaller dishes hidden in its “shadow”, resulting in an uneven clean across your load.

These bowls are packed so closely together, the dishwasher’s sprayers can’t reach every surface (Image source: Tammy’s Recipes)

The same also goes for cutlery – whether your knives, forks and spoons are standing in a basket or lying down in the top rack, make sure they’re nicely spaced so that one large piece doesn’t hog all the water from the other pieces.

Don’t let dishes touch

No, this isn’t an old-fashioned moralistic code.  We’re not chaparones, we’re doing the dishes.

Contact points between dishes can become the perfect spots for detergent or dirt to catch, collect and generally build up, so try to keep your dishes nicely separated.

Completely fill your dishwasher

Dishwashers are designed to do their best work when full, not just loaded with just a couple of items.  There’s no way to really guarantee the performance of a dishwasher that’s been filled unevenly.  Plus, running a cycle when the dishwasher’s not fully loaded uses more water and energy than you really need.

source: Piotrus on Wikimedia Commons

If you’ve only got a small load of dishes to deal with, check if your dishwasher has a Half Load cycle option – this concentrates its performance on one area only (usually the top shelf), so it cleans well while using less resources.

Use the right setting

Alas, there is no One Dishwasher Setting To Rule Them All (unless you can convince a throng of fantasy Dwarves to clean up after you).

The control panel of a Bosch Under Bench Dishwasher SMU50E75AU

Different dishwasher settings suit different loads of dishes, and mismatching these can often lead to problems.

Heavily soiled items like pots and pans with caked-on grots will need a very hot and strong setting to get a thorough clean, however giving your delicate glassware too powerful a blast in the dishwasher could actually damage them.

Check your dishwasher manual and use your best judgement to  determine which settings best suit your load with each wash.

Mind the spray arms

When you load your dishwasher, be sure that nothing blocks the spray arms from moving, including tall plates for an upper set or dangling cutlery for a lower set.

See the upper spray arms just below the top rack?  Make sure nothing stops them spinning, or your dishes on the top rack won’t get clean.

A spray arm requires its full range of motion to deliver its spray to all of the dishes throughout your machine, so you could end up with an uneven clean if its movement is restricted.

Don’t pre-rinse

It’s wasteful and ultimately self-defeating to pre-rinse your dishes before they go in the machine – without a bit of grot to stick to, the detergent may just wash off without doing its job, or a particularly intense detergent may start attacking your plates themselves, damaging them!

This approximate level of cleanliness/dirtiness is just fine for dishwashing (image source: Becoming Peculiar)

Of course, this doesn’t mean you should put dishes in the machine with whole chicken wings still stuck to them – give them a bit of a scrape down first to remove the excess, and if some food residue looks like it’s going to be tough for the dishwasher to shift, leave it to soak for a bit to soften everything up.

Clean the dishwasher

Before an appliance can clean something, it needs to be clean itself.  Think about it – if a washing machine gets filled with lint, your clothes will likely come out dirtier than they went in.  The same principle applies to dishwashers – don’t let your dishwasher become a device just for evenly distributing food particles across your dishes!

Image source: One Little Project

Cleaning a dishwasher is something that we’ve touched on before, but let’s summarise the basics for reference:

• Start by removing the racks.  If you find any food grots clinging to these, give it a scrub off.
• Next, check the innards and the sprayer arms for grots and scrub this away if found.  A toothbrush is usually about the right size here.
• Remove and clean the filter.  Yes, your dishwasher has a filter.  Not cleaning it is a problem.
• Put everything back into place and run a wash cycle while the machine is empty.  You might want to use lemon juice or vinegar in place of detergent, to help disinfect everything.
• Don’t forget the door seals!  But don’t clean them with anything too corrosive, or they could be damaged.

Check your water

Water pressure, water hardness, water temperature… lots of stuff can affect how your dishwasher cleans.  Be sure to check the dishwasher’s connections.

If your home’s water heater takes a long time to build up to a decent temperature when you turn on a tap, the same problem occurs in your dishwasher.  This can sometimes make it tougher for your dishwasher to cut through tough grease, as it tries to run a hot water cycle using lukewarm water.  In cases such as this, it’s often a better option to use a dishwasher with a cold-water connection, as these machines heat up the water to the required temperature themselves.

Clean the filter, and check the pumps so they’re not blocked.  Check that the drainage hose is clear and untangled, with no kinks.

Still having trouble?  Ask the experts:

If you suspect that your dishwasher may have something seriously wrong with it, your best bet is to contact the manufacturer – if it’s still under warranty, they should be able to organise a repair or replacement.

If you need a new dishwasher that will better suit your kitchen’s needs, then check out the selection at Appliances Online.  If you need any help deciding which one is best for you, contact our expert team on 1300 000 500 – we’re around 24/7, so we’re always ready to help!