It is one of the most common reported problems with a dishwasher besides obvious mechanical failure, dishes come out dirty at the end of a wash. Repeatedly we are asked why there are little specks, or grit on dishes and why plastics don't clean. In this article I will outline the most common of these and how to, hopefully, avoid many of the faults.
First off I'll start by pointing out that a modern dishwasher is better than the old kitchen sink for washing up the dishes. It is because the dishes are subjected to higher temperatures than your hands can stand (well most people at least) and therefore it kills more bugs, it's that simple. Further, when a dishwasher goes onto a drying cycle it is done by heat and steam, which your hands most certainly could not stand, and they actually almost sterilise the dishes and cutlery.
Then, on top of that, because you are not drying the dishes with a tea towel as most people will do, there's no transfer of germs from the towel to the plates and cutlery, it simply isn't required as you just put the dishes away once it's done.
Studies by various manufacturers also show that, on average, less water is consumed (or wasted) by using a dishwasher and less energy is used as you are not heating up water you don't need.
So, used correctly, the dishwasher is a fantastic machine and not just because it saves you time and hassle, but also it saves water, energy and is better for your well being. No mean feat for a simple kitchen appliance.
But if the dishwasher isn't used correctly, or simple user maintenance carried out, then they can become problematic and, you have to bear in mind, that whilst dishwashers are very, very good they are not perfect and can't wash everything.
Number one rule of a dishwasher: it is NOT a waste disposal unit!
Treating a dishwasher as a waste unit will get you in all sorts of trouble with it. Leftovers get into all sorts of places and, inevitably, cause problems. These problems can range from the simple almost burnt on residues, for which Weetabix is famed, to the little specks of grit left, to actually blocking something up and causing the machine real grief.
The short of it is don't put plates in that have masses of food left on them, plates need scraped off or even rinsed into a waste unit before you put them in the dishwasher. Failure to do so will cause you problems.
In almost every single instruction booklet there are instructions on how to load the machine and I know it's a chore to read these things, but you would be well served to make yourself familiar with how the basket layout has been thought out. They are not all the same, there are subtle differences, so even if you've had a dishwasher in the past it's well worth paying attention to this section.
The reason for mentioning this is that we often see poor loading. This leads to the spray not getting to the correct dishes in the correct places and it leads to poor cleaning.
For example, there are very, very few manufacturers that will recommend placing pots in the top basket as they don't get cleaned properly there because the spray pattern from the jets is not designed to cope with that intensive task there.
Another good example is the Fisher & Paykel Dishdrawer as, if you place mugs or similar in the top flip-down trays that are too tall it will stop the lid from closing correctly. This causes a leak, the machine faults to an F1 error and you need an engineer. You may even require new lid motors.
The simple moral is, have a read through the instructions, it may save you a lot of time, effort, grief and money.
It would be perfectly normal to think that the spray arms should never need touched but that's incorrect, the do from time to time, require to be cleaned. What happens is that grease builds up, little bits of rice or noodles and suchlike gets into them, forced down to the jet nozzle and stops the spray from working correctly. This will obviously impair how well the dishwasher cleans.
So they need cleaned on a fairly regular basis.
Most these days seem to clip off pretty easily for cleaning although some have a little screw, or nut, holding them in place but it's generally an easy enough task to clean them out. If there is a screw holding them on watch as normally it's "reverse thread" and turns in the opposite direction to loosen or tighten it.
This is, or at least should be, the most obvious cause of concern. At the bottom of any dishwasher is a large filter plate designed to collect all the bits of food that drop off the plates, it isn't perfect though and this is why spray arms get clogged up and it does require regular cleaning.
Obviously the more dirt on the dishes, the more often that the filters need cleaned. Thankfully this is, in most cases, a very easy task and merely involves a turn to unclip the centre "basket" type filter and then you lift the whole lot out.
My advice here is to wash in very hot water, run hot water through the filters to clean them including the "micro filter" this is the fine mesh one as that clogs up with grease and tiny particles of food.
This is very important user maintenance as, not only will it help massively to avoid poor results, it may actually help to avoid issues like blocked internal fill chambers. In other words, many of the problems we see reported in the forums are probably avoidable if only people actually followed the instructions and cleaned the machine regularly.
I know that this is very confusing due to certain manufacturers with detergent that claims to be all-in-one, 3-in-1, 4-in-1, 5-in-1 and whatever else they've managed to dream up but here's the low-down on rinse aid and why, if stuff comes out "streaky" from the dishwasher that it matters.
Rinse aid is often described as, "making water wetter". What that means in reality is that it breaks down the surface tension of the water allowing it to run off more freely which leads to a streak free drying process. Without it, or if you dishwasher isn't suited to using the various whatever-in-1 tablets, then you will get streaky dishes out.
Simple cure for that, buy and use some rinse aid.
Short of this is that we, engineers in general, don't really like tablets.
They cause problems, don't dissolve correctly, don't release the rinse aid component correctly, cause over foaming issues... need I go on? Speak to almost any engineer and they'll recommend powder, rinse aid and salt as we know it works.
Fairy Active Bursts are okay though as they are, essentially, powder in a bad, so we like those. It should be noted though that you may still need rinse aid and/or salt as well as these.
I essence if you look after your dishwasher, clean it regularly and load it properly you will very rarely encounter a problem and, in this article there's loads to check before you call an engineer out to look for a problem that might not even exist. It could save you a lot of money just doing some basic maintenance.
That's not to say that the faults and poor results cannot be caused by a failure, they can be, but it's best to eliminate all other possibilities before spending your money to find out you could have solved the problem yourself. Asides from which, even under warranty or insurance, many manufacturers will charge for these things as, to them, these are "customer misuse" faults and not a mechanical failure.