how to clean a clogged dishwasher

How to Clean & Unclog Your Dishwasher

There are some out there who find washing dishes by hand to be a pleasant, even therapeutic exercise - and with a window looking out on a nice view, it's not inconceivable. But for most of us? Dishwashing machines are an indispensable part of life, right up there with our smartphones. They may not be an absolute necessity, but can you really imagine life without?

How to clean and unclog your dishwasher

To keep a dishwasher running smoothly and effectively, regular cleaning and a bit of maintenance is required. Here, you'll find our tips for keeping your machine happy, as well as advice on dealing with poor drainage and clogs.

Cleaning

With hot, soapy water running through it all the time, you might think you can get away without having to actually clean your dishwasher. If only. In addition to the random bits of food that can find their way anywhere, you also have mold, mildew and limescale to contend with.

Dirty Filters: The most important thing to deal with is the dishwasher's filter, which catches all the bits and pieces of food that get left on your dishes after they're scraped (pre-rinsing is usually a waste of water; most modern dishwashers and detergents are more than capable of dealing with a moderate level of filth). Filters are usually located at the bottom of the machine below the bottom rack, which must usually be pulled out for access - refer to your manufacturer's instructions for specific instructions on getting to the filter.

Once the filter is accessible, remove the screen, canister or basket from the machine and thoroughly clean it with hot running water and dish soap. For stubborn debris, use a soft brush to gently scrub it out.
How often you need to clean the filter depends on how often you use the dishwasher, whether you scrape before loading, and the hardness of your water. Heavy users may do well to clean the filter every week, while infrequent users might get away with only an biannual cleaning. We recommend that you check your filter regularly, and clean as needed.

Gunky Doors: The dishwasher door is another spot to clean regularly - food and debris can find its way around the edges of the door (including the bottom) and around the door gasket. Use a damp cloth for light cleaning of the entire area; use a little dish soap and/or vinegar if that isn't working. Use a toothbrush or other soft brush to remove stubborn bits.
Deep Cleaning: For a combination de-liming/deep cleaning, fill a container with 1-2 cups of white vinegar and place the container upright on the rack of an empty dishwasher (depending on the design of your machine, you may want to put it on the top or bottom rack for superior cleaning - if your manual doesn't specify, try each rack out). Run a full cycle at the highest temperature to thoroughly clean and disinfect the machine interior. The action of the dishwasher will disperse the vinegar throughout the interior. Do this at least every few months, or whenever the dishwasher starts to smell.

Clearing Blockages

If your dishwasher is underperforming or not fully draining, there's probably a blockage somewhere. You should be able to tell where the blockage is by the symptoms: slow or no draining indicates an issue in the dishwasher drain or drain hose, while lackluster cleaning points to clogged spray nozzles.

Safety first! Always disconnect the power supply (or cut off power to the breaker) to the dishwasher before attempting to deal with clogs.

Clogged Spray Arm: The nozzles of the dishwasher's spray arms can be easily blocked by food debris, and even mineral deposits from hard water. If you notice a decrease in cleaning power, or actually see something blocking the holes, you'll want to check your owner's manual for instructions on how to remove the arms. Once removed, soak them in a solution of vinegar and water for at least 20 minutes, then carefully clean out the holes with a pipe cleaner or paperclip (don't use toothpicks, which can break off inside the arm).
Clogged Drain Hose: If your dishwasher is draining slowly or not at all, the problem is likely a blockage in the drain hose. These kinds of clogs are more common the less scraping is done before loading dishes, and when the dishwasher is drained through a garbage disposal (which can contribute its own debris to the drain line). To clear it, you'll need to temporarily disconnect the hose from the machine.
Pro Tip: If your dishwasher drains via a garbage disposal, make sure to briefly run it with some water before starting a load - if the disposal is full or waste is still in the drain line, it can disrupt dishwasher draining.

Consult your owner's manual if you're unsure where the hose connects to the dishwasher drain (usually at the back of the unit). There may be an access panel below the sink, and if you're lucky, your model allows for easy access to the hose by simply removing the kickplate/bottom panel, but you'll probably have to pull the dishwasher out.
In order to pull the machine out, remove the kickplate or bottom access panel of the unit - these are usually secured by way of a couple of screws or bolts. Unless you're absolutely certain that the installer (or yourself) left enough slack in the power supply line to pull the machine all the way out from under the counter, your next move will be to disconnect the power supply by removing the twist-on wire connectors ("wire nuts") found in the electrical junction box. This box is usually at the bottom front of the machine, accessible once the kickplate has been removed. Simply remove the cover of the junction box and twist the connectors to release the electrical wires. The water supply to the dishwasher should also be disconnected, unless you're certain there's enough slack to pull out the machine. Use channellock pliers or a crescent wrench to turn the nut on the supply line.
Place a drip pan, casserole dish or similarly flat basin below the hose connection to catch any water that may spill out once the hose is removed. Do the same for the connection to the garbage disposal or sink drain tailpiece.
Helpful hint: If your dishwasher does not slide out with a minimum of effort, it may be mounted to the counter - don't force it! A confident DIYer can temporarily unmount the machine by removing the screws on the brackets, but if you're at all unsure it's best to call a professional.
Dishwasher drain hoses are almost always connected using either a worm clamp (aka hose clamp) whose screw can be turned to loosen it, or a spring clip that needs to be squeezed to release its grip. Disconnect the hose from the dishwasher as well as under the sink. Slide the clamps or clips off the hose, and place them in a secure place so they aren't lost.
Examine the hose for any kinks, cracking or brittleness and replace it immediately should any be found. Otherwise, gently bend the hose back and forth to help locate and dislodge any stubborn blockages. Use a garden hose (which should have greater flow and pressure than, say, a kitchen spray nozzle) to blast water through the drain hose to flush out most clogs.
For tougher clogs, create a simple cleaning tool by straightening out a wire clothes hanger - do not leave any bent ends! Gently but firmly use this to break apart blockages, taking care not to push too hard against the walls of the drain hose (which can be punctured). Do this outside, over a sink or tub, or over a drip pan/casserole dish to keep the mess to a minimum.

Clogged Drain Sump: If the hose looks to be clear, the blockage could lie in the dishwasher drain itself - or more specifically, the small sump at the bottom of the machine. This is the hole through which all the wastewater exits, and it can get clogged despite having a cover over/around it. Remove the cover (it may pull straight out, or you may need to pinch and pull) and pull out any debris (your straightened clothes hanger might help here, too).
Clogged Air Gap: Air gaps aren't part of every dishwasher installation (many areas accept the "high loop" drain hose arrangement as sufficient backflow protection), but if you have one, it's another spot to check for blockages. Clogs involving the air gap (or the line between it and the sink/garbage disposal) will usually make themselves known: water from the dishwasher that usually drops through the gap with some slight leakage will start spilling out at a much greater rate.

Remove the air gap cover and take a look inside. If you see any gunk inside, try cleaning it out with a bottle or pipe brush, or flushing with hot water (a funnel may be helpful given the size and design of the air gap).
Blockages can also make their way to the hose between the air gap and sink drain/garbage disposal. Like the dishwasher hose, these are usually secured with a worm clamp or spring clip. If you suspect a blockage here, completely disconnect the hose and flush it out.
You can learn more about air gaps and how to deal with a leaking one here.

Pro Tip: If you've tried everything above and are still experiencing drainage problems, the issue may lie in the kitchen drain line itself. If this is the case, you should also observe slow draining of the sink. Try using a drain auger (aka "snake") down the sink drain to get things moving again.

Maintenance

In addition to regular cleaning, there are a few maintenance tasks you should try to keep up on to ensure your dishwasher continues to run effectively and without incident. Remember to cut off power to the dishwasher if you'll be moving it, or whenever you're dealing with interior components.

Regularly check that the dishwasher door closes tightly. If it's at all loose or there's a jiggle, it'll need to be tightened to prevent water from escaping, and to keep the machine from turning itself off mid-cycle when it detects an open door. You'll need to check the manufacturer literature for specific instructions on how to tighten your door; some must have a spring mechanism at the bottom adjusted, others will have an adjustable latch plate on the top frame of the machine.
While you're checking out the door, also inspect the gasket around it. Should it be damaged, dried out or otherwise compromised, you should be able to easily find a replacement locally or online. If you're still within your warranty period, check to see if the gasket might be covered first.
If water is on the floor but the door and gasket look to be fine, the problem could be an unlevel machine that tilts to the front or side, allowing water within to pool and leak out. A proper installation will avoid such an issue, but it does happen. If the bubble in your torpedo level isn't centered when you check the front edge and interior floor of the dishwasher, you'll need to check your owner's manual for specific instructions on adjusting the dishwasher feet. Typically, you'll only need to remove the kickplate to access the front feet, which are often adjusted via crescent wrench. If the back feet need to be adjusted, the unit will need to be pulled out. If the dishwasher is mounted to the counter, it'll need to be unmounted first. If the feet are damaged or you simply can't get the level right, wooden shims under the machine are an easy, inexpensive solution.
It's a good idea to inspect and clean out the float assembly (or "float switch") every few months (or more frequently if your dishwasher is in constant operation). A small cylinder found on the floor of the machine, the float controls the water level inside the dishwasher. One that's jammed with debris can lead to flooding and other water level problems. Most float assemblies have a cover over them that can be pulled off; some may require a screw or two be removed first. Carefully clean around the mechanism with a sponge or bottle or pipe brush - if the cover cannot be removed, do your best to clean under and around it. The float should be able to slide up and down with ease once clean.
Always keep a close eye on the dishwasher's racks: any chipping or wear of the coating needs to be dealt with immediately to prevent further damage and rusting of the underlying metal (which can send metal flakes into the dishwasher pump, and onto your dishes). You should be able to find replacement tine tips at your local home improvement store, which simply slide onto damaged ends. For more serious repairs, look for dishwasher rack paint.