Every day, your dishwasher cleans cutlery, pots, plates, and glasses from food residues – cleaned, and dried so that you can look forward to sparkling dishes without any problems. However, if you notice that the dishwasher is increasingly leaving dishes dirty, you could have a problem.
Depending on the age of the machine, the last time it was cleaned and the wrong dosage of detergent, problems can quickly arise in the dishwasher that severely impairs the cleaning performance. If nothing is done about these problems, you usually have to scrub the dishes or dry them by hand, which defeats the purpose of you getting a dishwasher in the first place.
Don’t panic, it’s very unlikely that you’ll need a new dishwasher or anything serious is at fault, so let’s get to the bottom of this dishwasher leaving dishes dirty.
Common Causes of Poor Dishwasher Cleaning
Since the dishwasher is used every day to clean dirty dishes, dirt, food waste and limescale build-up in the machine over time. But it is not always just a clogged filter to blame for this poor cleaning performance, there are a number of possible causes, including:
- Not regularly cleaning filters
- No or too little dishwasher salt
- Dishwasher loaded incorrectly
- Incorrect cleaning cycle for load
- Not pre-scraping and rinsing dishes by hand
- Glasses washed with other dishes
- The dishwasher tab compartment failed to open
- Jammed spray arms
- Kinked waste water or inlet hose
- Defective internal components
Dishwashers often only suffer from one of these causes, so it is not a problem to systematically check them. In this way, you can determine within a few moments what the cause of the problem is and act, for example in the case of a strainer clogged with food residues.
Therefore, when checking the individual elements of the dishwasher, you should make sure to look at them carefully so that you do not forget anything. This is the only way to prevent further problems with washing up.
1. Cleaning Dishwasher
Due to its function, the dishwasher should be cleaned regularly so that grease, food residues and small parts do not get stuck in the drain and hard to reach places. This is especially important if you have washed a large number of dishes over a long period of time but have neglected to clean the dishwasher filters and drain.
It is important that the interior of the machine remains clean, especially the following components, as these parts if left unclean will lower the dishwashers cleaning performance.
- Drain filters
- Cutlery basket
- Rubber seals door seals
Dirt and food chunks can collect and build up around these areas of the appliance internals and could be a reason for dishes showing up with dirt after a wash run. You should remove coarse food residues before you put the dishes into the dishwasher. Bits of pasta, noodles, rice, mincemeat, onion, and crumbs on plates and bowls will eventually cause a drain blockage, so always scrape off plates and run them under water before each cycle.
You should be checking the drain filter weekly, run a dishwasher cleaner, from Bosch or Finish, into the empty dishwasher every two months or so and run on a program with at least 60 ° C to help with internal cleaning.
A tell-tail sign that your dishwasher is very dirty is an unpleasant smell when you open the door. Since a lot of organic substances are deposited inside, they can start to decay and then smell bad, which you can prevent by regularly cleaning and emptying the machine.
2. Salts and Tabs
In order for the dishwasher to work effectively, it needs the correct dosage of different detergents. Depending on your model and if you live in a hard/soft water area, your machine will have washing aid requirements for optimal cleaning.
- Rinse aid
- Dishwasher salt
- Premium Dishwasher Tabs or Powder
It is typical for consumers who use powder instead of tables to automatically add rinse aid and dishwasher salt to their dishwasher. These products are also necessary when using tabs, as the amount of rinse aid and salt is never enough to really work effectively.
While the tabs and the powder work as a strong cleaning aid that breaks down oils and dirt, the salt regulates the hardness of the water and the descale works against possible limescale stains that mainly appear on dishes and glasses. Make sure you’re using all of the correct cleaning aids and salt for your appliance to maximize efficiency.
Related: Dishwasher Salt Indicator Constantly Flashes
3. Incorrect Loading
Loading dishes incorrectly often leads to poor washing results. Things like dishes piled on top of each other or too close together, or placed the wrong way round means the water jets cannot reach the dirty surface.
Here are some of the worst offenders:
- pots, pans, bows, cups, and glasses should be upside down
- Chopping boards and frying pans should not cover the face of plates
- Cutlery heads should face up
Since the dishwasher does not have any brushes, it is necessary that the individual plates, cups, casserole dishes, pots and cutlery are arranged in a way that allows the water jets to spray across them completely, and allow dirty water to drain away freely. In addition, never stack dishes in a pile on top of each other, expose all the dirty surfaces for cleaning.
Making sure you wash sensitive glasses alone is the correct cycle mode. Due to their bulbous shape, these could be made dirty by leftover foods.
4. Wash Modes and Temperature
Heat is one of the most powerful cleaning elements of a dishwasher and is set in the device by the respective cleaning program.
Many people want to save electricity and mostly use the dishwasher’s eco function, which washes at a temperature of 40 ° C. This is sufficient for washing light soiling, but it only has a moderate effect on grease and stubborn dirt. It’s not hot enough to break down bakes on grease or encrusted plates. For this reason, you should always wash tougher loads with at least 60 ° C and your dishes will come out cleaner.
Here’s a guide on dishwasher temperatures to maximise cleaning:
- High program (60 ° C): best for cleaning heavily soiling cookware
- general program (50 ° C): best for everyday use on moderately soiled loads
- Short program (45 ° C): best for light / medium dirty dishes
- Eco program (below 40 ° C): suitable only for dishes requiring light washing
You should also make sure that you always pre-wash by hand or choose a rinse cycle that has a pre-wash level. This helps to soak stubborn stains and grease for easier cleaning. As already mentioned above, you should always remove coarse food debris before putting it into the dishwasher.
The auto program is highly recommended if your appliance has one, as it adapts the current wash cycle to the number of dishes inside. In this way, it sets the heat for optimized cleaning.
5. Glasses
As mentioned above, glasses suffer greatly from too many dishes, coarse dirt and not enough salt. You can easily prepare glasses for a wash cycle by pre-cleaning them and then placing them in an empty dishwasher.
Large gin and wine glasses belong in this category, as they often suffer from cloudy streaks. Nevertheless, glasses should never be washed too hot, otherwise, they could easily break and thus they do not belong in the same load as the baking pan after the macaroni bake.
Glasses can lose their shine and become matte if you don’t use the correct wash setting and cleaning aids. Always wash glasses in a separate cycle from things like steel pots and ceramic dishes, as they require lighter cleaning. If you only have a couple of glasses to clean then wash by had to keep them looking streak-free.
6. Dishwasher Tab Compartment
If you find a half-used tablet or powder in the machine, or if the dishwasher only smells of water and dirty dishes, it is likely that the door of the dishwasher tab compartment has not opened properly during the cycle.
check to make sure there are no cooking utensils or anything out of place that could be obstructing the tab compartment flat from opening. If the powder runs out, it is washed away in the pre-wash cycle. Avoid doing this as it will wastewater. If the compartment blocks, detergent cannot be added to the water.
Make sure that you close all other compartments securely so that no detergent or tab spills out. This can also lead to stains from the detergents on the dishes and cutlery. If you suspect that the release mechanism is faulty, call in the professionals.
7. Spray arms
The spray arms are essential for the dishwasher to do its job – clean dishes thoroughtly. They spin and spray your dishes, blasting away dirt at high pressure, but only if they’re able to spin freely.
Without spinning splay arms and nozzles, your dishes will leave the dishwasher still dirty. If only one side of your dishes is clean, this is often an indication of problems with the spray arms, as they only clean part of the dishes. Although all of the dishes in the machine get steam, the cleaning effect of steam alone is not sufficient.
Often the spray arms jam due to being overloaded with dishes that are pressing against the arm. Also, big spoons or knives parading from a rack will block the arms from spinning. I always spin both arms and visually check there are no obstructions before starting the machine.
8. Kinked Hoses
The wastewater hose is an essential part of the dishwasher as it directs all of the dirty water and tiny food particles from the machine down the drain. If it kinks, water and particles collect in the hose and dirt can be returned to the machine. Theoretically, the water is whirled up again and after the wash cycle, a layer of fat droplets often remains on the dishes.
Another sign of this is unclean smells, even with a clean machine. It is best to store the hose in an elevated position so that it does not kink. Go ahead, give all those hoses a check over!
9. Broken Internal Components
Another reason for your dishwasher’s poor cleaning could be that internal components like piles, pumps, heating elements are wearing out or broken completely, which will limit the cleaning performance. This can have many causes that can be found by a professional or by giving your appliance service.
- Damaged heating elements
- Damaged sensors
- Damaged door mechanism
- Computer fault
- Spray arms no longer spin or blocked
These symptoms are often difficult to diagnose without the help of an appliance engineer, but defective heating elements can be recognized by the fact that no steam is generated after the wash cycle and the dishes are cold and wet.
As soon as the dishwasher cannot generate enough heat, thorough washing is impossible and you should contact a professional. For example, if the dishwasher’s control unit is damaged, the water may not be pumped out or even fed into the machine.
If you find a dirty puddle of water and dirty residue over dishes, then you may have a faulty drain pump. There are lots to think about and check over here, but you’ll find that a dishwasher that is not cleaning properly will have one or more of the faults mentioned in this article.
