Can A Dishwasher Have Its Own P-Trap? (Answered!)

P-Traps are one of the most common and tried-and-true solutions to the problem of sewage odors coming from the primary […]

Share This Post

P-Traps are one of the most common and tried-and-true solutions to the problem of sewage odors coming from the primary drainage in our homes. The use of a P-Trap makes it possible to prevent not only unpleasant odors from sewers but also the back-flow of water and the buildup of debris. It’s crucial that every part of the house where contaminated water flows are equipped with its very own P-Trap.

Dishwashers and P-Traps have been the subject of a much-heated discussion over the past few years. One of the main concerns of most people who are not that familiar with plumbing is if it’s possible for a dishwasher to have its own P-Trap.

In this post, we will answer the most common question that people have about P-Traps and dishwashers: can a dishwasher have its own P-Trap?

Yes, it’s ideal to have a separate P-Trap for your dishwasher if at all possible. Having a unique P-Trap installed in your dishwasher enables it to be free of the intolerable stink as well as the poisonous gases that are often connected with your sewage.

Let’s take a closer look at the relevance of having a P-Trap for your dishwasher and have a deeper understanding of how the P-Trap works with the dishwasher.

What is a Dishwasher Back-Flow Preventer?

The primary role of the plumbing component known as a dishwasher back-flow preventer is to stop sewage gases from entering the dishwasher. It’s a one-way gate that lets polluted water and gas flow into your sewage system, but it stops the water and gas from flowing back into your sink or dishwasher whenever it tries to go the other way.

A pipe that has been bent into the shape of a letter “p” is known as a P-Trap. In plumbing, a back-flow preventer is often a P-Trap that’s positioned to create a U-shaped barrier. In most situations, P-Traps are placed together with sinks, dishwashers, commodes, and showers.

P-Traps catch water underneath. It serves as a seal to stop the contamination of gases and water. Because the water is so clogged, any odor from the sewage can’t make its way through and into the dishwasher.

When the dishwasher is installed separately from the sink, you’ll find the P-Trap at the bottom of the pipe coming out of the air gap. It’s easy to find a P-Trap because it looks like the letter P. If you can’t find anything like it, then look for something like the S-Trap.

4 Reasons Why Dishwashers Need a P-Trap

In addition to the sanitary benefits it offers, having a P-Trap offers a variety of other numerous advantages too. Here are some of them:

  • P-Traps Keep Foul Odor Away

The primary objective of installing a P-Trap in your dishwasher is to eliminate any odors that come from the sewage. The P-trap is shaped in a way that allows it to collect water along its curves. When you switch on the inlet of your dishwasher, the P-Trap, if your dishwasher has one, is triggered into action and activated. The contaminated water that’s being flushed out of your dishwasher is gathered in the P-Trap prior to being drained out and transported to your major drainage system. This water is then replenished with new, clean water that comes in from your inlet. The water in the trap prevents this stench from entering the dishwasher.

  • P-Trap Protects You from Poisonous Gases

The foul odor coming from your sewer is the least of your worries when you’re exposed to the polluted gas coming from your sewer for a long period of time. Prolonged exposure to toxic gases that contain sulfur dioxide, ammonia, hydrogen sulfide, and methane like sewer gases may cause serious health issues like lightheadedness, sinusitis, pneumonia, bronchitis, exhaustion, and irritability.

  • P-Trap Prevents Clogging

A trap needs to be put in place on the dishwasher’s waste outlet to avoid clogging.  P-Traps contain debris and blockages that would otherwise result in clogging and, eventually, environmental contamination from overflow. As a result, this debris is contained within the U-shaped structure, which also features an outlet that’s been carefully designed to easily open whenever you need to drain the debris contained inside.

  • P-Trap is an Added Protection Against Accidental Loss of Property

Even though it seldom occurs with dishwashers, if a valuable object like jewelry were to mistakenly fall into the drainage, the p-trap would stop it from going into the sewer.

  • P-Trap Allows You to Follow the US Plumbing Code

Installation of P-Traps has been made obligatory by the government in the plumbing regulations in order to ensure the construction of sanitary sewage systems.

Do Dishwashers Have a Built-In Trap?

Most dishwashers don’t come with their own built-in P-Trap. P-Trap needs to be bought separately and installed at the same time as you are installing your dishwasher.

Most professional plumbers connect the drain line from the sink to the dishwasher. This is because there’s usually a P-Trap underneath the sink. While you can have a P-Trap for the sink and the dishwasher separately, it’s not necessary as one P-Trap is sufficient for both the sink and dishwasher.

How Do You Hook Up a P-Trap on a Dishwasher?

It’s necessary to install a trap within the drainage system of the dishwasher in order to stop the gases from entering the appliance. If you’re fortunate enough to be putting in a brand-new drainage system, the P-Trap will already be included in the package that you purchase. They’re also manufactured separately though, so you can still purchase them for replacement.

Step 1: Get the Correct P-Trap

P-Traps are made of different materials, either PVC, black ABS plastic, or chromed metal, and come in different sizes from 11/4-inch 11/2-inch to 2 inches. When purchasing a P-Trap to use, check the drain fitting of your dishwasher first.

Step 2: Test-Fit the Trap

Even if you’re certain that you have purchased the correct trap, you still need to test it before actually installing it. Keep your hands on the u-part while you adjust its position relative to the other pipes. When you’re aligning the trap, you need to make sure that it’s aligned properly with the wall pipe and the tailpiece that connects to the dishwasher.

If the new arm’s length is going to be too long to connect to all of the pipes, feel free to use a pipe cutter to shorten it before you try to attach it. Make sure not to damage the ends of the pipes.

Step 3: Position the Nuts

Move the nut thread onto the existent pipes, and then position the nut so that it’s pointing downward. Connect the P-Trap to both apertures and make sure they’re in line with the nuts before tightening them. The nuts must be sufficiently tight to stop leaks.

Step 4: Connect the Dishwasher Drain Pipe

The tailpiece of the majority of kitchen drainage systems is situated just above the P-Trap. A tailpiece is a little protruding pipe where the dishwasher’s hosepipe connects to the water drain.

Threads and nuts should be slid in. After that, attach the dishwasher’s hosepipe to the tailpiece and tighten the bolts.

Double-check the nuts and make sure that everything is set up correctly. If the system is connected to a sink, you may check it by turning on the dishwasher or opening the sink.

Examine the areas beneath the joints to make sure there aren’t any leaks. If there is seepage, simply tighten the nuts.

Can a Dishwasher Drain After the P-Trap?

The dishwasher drain pipe will be useless if it’s added after the P-Trap. If there are no obstacles, the dishwasher will be completely filled with the odor of sewage.

Here is how the sequence goes:

sewage > dishwasher > drain pipe > air gap > garbage disposal > P-Trap

Therefore, the drainpipe will go from the dishwasher all the way to the air gap. The pipes are going to connect to the garbage disposal. The pipe that’s flowing out of the disposal unit will then go into the P-Trap, and after that, it will flow into the sewage system. Additionally, it will be equipped with a vent linked to it.

There’s no way to change the sequence above. That rules out the possibility of installing a drain line after the P-Trap in the plumbing system. This will result in the P-Trap being ineffective and the toxic gas entering the dishwasher. A P-Trap, however, cannot be installed before the disposal device.

Particles of food will find their way into the P-Trap located in the dishwasher. It’s important to assemble your drainage system following the procedure above to make sure the P-Trap will work correctly.

Why Do Dishwashers Not Drain?

There are several reasons why a dishwasher won’t drain. Here are the top 3 reasons:

  • Clogged Filter

Checking the filter should be the first thing you do if you find that your dishwasher won’t drain. A dishwasher’s filters are an essential component that must be properly maintained in order to ensure the appliance’s optimal performance. Cleaning the filters in your dishwasher should be done at least once every two weeks if you want to keep your dishes clean and maintain the life of your equipment. Filters collect soft food particles and prevent excess food and oil from being redeposited within the dishwasher by removing them before they can settle back down.

What to do: The first thing you need to do is find your filters and take them out of their housings. You’ll find them at the very bottom of the dishwasher, just below the spray arm that’s located in the bottom rack. To remove the filter from the dishwasher, start by turning the cylindrical filter in a clockwise direction or follow the arrow that’s usually printed in the body of the filter.

After the cylindrical filter has been taken out of the way, the metal mesh filter plate needs to be lifted up and out of the way. Check the sump, which is the bottom pit situated beneath both filters, to see whether any large food deposits have fallen into that area and are causing the clog.

In order to properly clean the filters, you’ll need to rinse it under running water in order to remove any food residue or built-up grease. You might want to try using hot soapy water with a sponge or even an old toothbrush to remove extra-tough dirt off the surface.

  • Blocked Drain Hose

Because it directs dirty water away from the appliance, the drain hose is an essential component of every dishwasher. Typically, it’s linked to the same drain pipe as the sink in the kitchen. Even though it’s unlikely, the drain line might be clogged with built-up filth and food waste.

What to do: Take the drain hose out of the dishwasher and sink drain in order to clean it. If you don’t have a lot of experience resolving problems with plumbing, it’s preferable to get assistance from a professional.

  • Damaged Drain Pump

A drain pump, like the filters in a dishwasher, is susceptible to being clogged with leftover food particles and grease that’s built up over time. This will stop the water from draining once a cycle of washing has been completed. The area next to the pump’s impeller is typically the best place to look for any debris that may have made its way inside the pump. It’s easy for foreign things like broken glass to find their way into the drain pump, which can then hinder the pump from functioning properly. This can easily be detected by simply paying attention.

What to do: The dishwasher’s bottom must be opened in order to inspect the drain pump. Because of this, you’ll need to take off the base plate and disconnect the hose that leads to the inlet. In addition to this, you’ll need to use a multimeter to obtain a measurement of the pump’s resistance to confirm that it’s operating well. Call a certified plumbing specialist to fix your dishwasher for you if you don’t feel comfortable executing any of these steps or if you don’t want to risk voiding the warranty on your equipment.

Share This Post

Scroll to Top