Dishwasher cleans dirty dishes better than rinsed dishes

I keep reading even on CHOICE site that you should not rinse dishes before putting them in the dishwasher. I would like the experts to explain how does the dishwasher adjust it’s cleaning within a normal or quick cycle (no pre rinse cycle) for two plates for example placed right next to each other - one rinsed and one not rinsed? 2nd question - surely not rinsing items would mean more muck in the filters, so more filter cleaning required?


As he can be reliably relied on to do, I trust @airedale will reply.


My mini dishwasher isn’t very efficient at cleaning dirty dishes so I have reduced my usage to whenever I feel like its time to give them a super clean as opposed to my normal half baked in the sink efforts. They do come out “bright and white” but only if they get rinsed first.


Hi @DJR , yes, we recommend not pre-rinsing your plates, just scrape solids into the bin or compost and go. The reason is, modern auto-sensing dishwashers check how dirty your plates are by measuring the level of soil in the initial rinse using a turbidity sensor - they then adjust their program accordingly. If you pre-rinse then you might trick your dishwasher into thinking your plates are cleaner than they actually are, so it may use a less intensive wash, which can actually leave your plates dirtier at the end of the cycle.
How do we know these auto sensors work? By washing clean plates (when we test drying performance) and measuring the energy and water used. If these figures are different to when we wash dirty plates, we know the sensor’s working.
As for what happens when rinsed and non-rinsed plates are racked together, the dishwasher will take an average - it’ll think it’s full of moderately soiled plates, not a mix of heavily and lightly soiled ones.
What happens for a quick cycle with no pre-rinsing is a good question. We don’t know for sure, but looking a the numbers, short cycle programs tend to be quite energy intensive, which would suggest a lot of heat to get the job done in a shorter timeframe - it would be the opposite of a ‘low power’ mode, and may use more energy and water than a regular normal or auto cycle. Of course, if your crockery comes out dirty then either use a longer cycle or if you don’t want to change the cycle then yes, pre-rinse everything (but don’t tell anyone I said so).
There’s a couple of other reasons not to pre-rinse - firstly, it’s going to drive your water consumption way up - dishwashers are an incredibly water efficient way to get your crockery clean, but if you pre-rinse then you’ll be negating this efficiency. Secondly, you pay a lot of money for your dishwasher, and pre-rinsing is showing a complete lack of faith in its ability to do the one thing you bought it for.
Yes, skipping the pre-rinse does mean you may need to clean your filters more often, but chances are you need to clean your filters more often then you currently do anyway - I know I do.


My experience, if dishes are washed right after every meal, not required to prewash. If dishes are left from breakfast to dinner to wash, of course some dry stain dishes are hard to remove completely by machine. It needs human intervention :))



Our Dishwasher probably doesn’t have that sensor feature, so I’ll stick with soaking some items, like frying pans with stuck on stuff, in one of the twin sinks before we put them in.

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Mine definitely doesnt. Its a cheap “mini” dishwasher from Midea, and I tried going the no-rinse route and had to wash everything again, what a pest! It does a nice job but these days I only use it from time to time. Must be time to sell it and get a different benchtop model which should be plumbed in (its a bit of a nuisance having to fill it with a jug every time)

Welcome to the community @Hongmai.

We have a Miele, which is now nearly 6 years old and live off roof - tank water. It’s a limited supply.

To save water we only run once a day when then DW is full. Usually in the middle of the day when the solar PV is at it’s best. It has an auto sensor cycle which we use all the time. Any really dirty dishes we first wipe over with a paper towel or the used napkins - from last nights tea time.

We wash the fry pan, cooking pots etc once a day by hand. They are also wiped semi clean while warm after use. They simply take up too much room in the DW. They also benefit from a pot scrub cycle which is hotter and longer than standard. Which is more than the other items need.