Dishwasher Drain Hose Too Long? (We Have a Few Fixes)

Dishwasher Drain Hose Too Long

An improperly installed drain hose is one of the most common occurrences when it comes to dishwasher installations. In fact, if you’ve found yourself wondering if your dishwasher drain hose is too long, it was most likely installed incorrectly in the first place.

If your drain hose is currently positioned lower than the connection to the disposal, resting on the bottom of your cabinet, or on the floor, you need to either implement a high loop or install an air gap. One of these two solutions should correct the issue of your drain hose being “too long.” They will also prevent your dishwasher from becoming flooded with wastewater and all of the unpleasant smells that come along with it.

Don't want to do it yourself?
Get free, zero-commitment quotes from pro contractors near you.


Dishwasher Drain Hose Too Long?

If you believe that your dishwasher drain hose is longer than it should be, it was probably installed wrong. Since you can’t necessarily cut a drain hose and you likely want to avoid running out to purchase a smaller one, consider your other options first. If you think your drain hose is too long, try one of the following methods:

  1. Install a dishwasher air gap
  2. Loop the drain line higher than the connection to the disposal, or the “high loop” method

What Is a Dishwasher Air Gap?

A dishwasher air gap is a fitting affixed roughly two inches above your kitchen sink. Its primary purpose is to prevent contaminated wastewater from entering into the dishwasher from the drain through backflow. Installing an air gap is a simple solution to ensure that wastewater and potential contaminants do no re-enter your clean water supply.

When you are running your dishwasher through a cycle, the last thing you want is for your dishes to come out covered in grime from your clogged garbage disposal. The air gap will completely separate the hose depositing dirty water from the hose that is running to the drain. With this, the two pathways will never connect, and there is no risk of wastewater seeping back into your appliance.

If you suspect that your dishwasher drain hose may be too long, it will likely benefit from installing an air gap.

How Does Backflow Work?

Put simply, backflow is the unsolicited backward flow of water, leading polluted water and contaminants back into the clean water supply. Dishwasher air gaps are one form of backflow prevention. When it comes to plumbing, the point where wastewater could contaminate potable water is known as a ‘cross-connection.’

Cross-connections can result in backflow when there is a shift in pressure. For instance, if your kitchen sink drain becomes clogged, the hose that leads to the drain will start to distribute the dirty water back into your appliances. Without a dishwasher air gap, or another type of backflow prevention, your dishwasher will flood with wastewater.

How Does an Air Gap Work?

When you install an air gap on your dishwasher it physically separates two branches of hose with air to guarantee that cross-contamination between the drain and dishwasher does not occur. One branch of this air gap fitting is attached from the dishwasher to the air gap, while the other goes from the air gap down to the garbage disposal attachment.

The dishwasher drain hose comes out of the dishwasher and curves upward. At its highest point, the branch ends and water exits the open end of the tube, goes through the air gap, and escapes into the second branch. The second branch is what carries the wastewater to the designated drainage location. These two branches are installed beneath your countertop or sink and the fittings extend above the counter.

Do I Need an Air Gap?

Air gaps are the most effective way to prevent your drain from cross-contaminating your dishwasher with wastewater. If you want to safeguard your dishwasher against flooding with polluted water, you need some form of backflow prevention. Although air gaps are not the only option, they may be required by plumbing code in some areas.

Also, while other backflow prevention methods can dissuade cross-contamination, an air gap is the only technique that guarantees protection against wastewater escaping into your appliances. In fact, most plumbing codes across the United States require commercial food and beverage prep sinks to possess an air gap. Whereas, states such as Minnesota, California, Hawaii, and Washington require dishwasher air gaps residentially.

Consider installing an air gap to both ensure that your home is up to code and correct any issues with your dishwasher drain hose being “too long.”

How to Install an Air Gap

Installing a dishwasher air gap is a relatively easy project that most homeowners can easily achieve without the need for a certified plumber. Follow these steps to install an air gap on your dishwasher:

  1. Look under your counter for the air gap hole. Most counters will have a hole precut for this exact purpose. If the opening does not already contain an air gap, it may be covered by a flat disc-like concealment. If you don’t have an air gap hole, you will have to drill one before proceeding.
  2. If you already have an air gap hole, move to the next step. If not, use an electric drill and hole saw to cut a 1-3/8” hole in your countertop. Make sure that the hole is close enough to the edge of the sink so that the air gap will have enough room to drain should the tubes overflow. Before you begin drilling, protect your countertop from scratches by taping off the area around the hole.
  3. Once you’ve located your air gap hole, connect the air gap to the dishwasher drain hose. The drain hose will connect to the small side of the air gap. Affix the 5/8” tube to the 5/8” end of the air gap. Then, tightly fasten the tube using stainless steel hose clamps.
  4. Connect the air gap to the garbage disposal or drain hose. Next, you’ll want to measure and cut a piece of 7/8” tubing to attach the air gap to either your garbage disposal or intended drain. If you want to run the air gap to the drain, affix the tube to the Y-branch tailpiece that connects the drain to the sink and fasten with a hose clamp. Alternatively, if you are attaching the air gap to your garbage disposal, locate the tube coming out from the side of your garbage disposal. You may need to remove the metal plug inside if an air gap has never been previously installed. Ensure that there are no bends in the tubing and then attach the 7/8” tube to the disposal and fasten with a hose clamp.
  5. Press the air gap out of the hole on the counter. First, take off the vanity covering on the heading of the air gap and place it into your counter hole from below. Tightly secure the air gap against the counter by threading a nut alongside the air gap’s threads. When you’ve threaded the nut manually and stabilized the air gap, use a wrench to ensure that the air gap is fastened securely to the counter. Finish up by replacing the vanity cover on the air gap.
  6. Test your dishwasher. To test your install, run a full cycle on your dishwasher. While it’s running, lookout for any signs of leaking in the air gap or tubing connections. There should be no water escaping from either the garbage disposal or the air gap.

What Is a High Loop?

Your other option if you suspect that your dishwasher drain hose is too long is to loop the drain line higher than the connection to the disposal, or designated drainage site. Otherwise known as the high loop method, this backflow prevention technique involves running the drain line from the dishwasher to the highest point underneath the sink. The loop is fastened beneath the counter using a bracket and drains down into the garbage disposal or sink drain.

The physics behind the high loop is that the drained water from the dishwasher is forced to travel up before it can escape out the drain. For best results, high loops should be at least 32” above the floor of your kitchen. If you do not have a clearance of at least 32” between the peak of the high loop and the ground, you will need to install an air gap instead.

With a high loop, the tubing is installed at such a drastic slope. As a result, the wastewater is very unlikely to backflow when the high loop is properly installed. Although the high loop method is classic and effective to prevent backflow, it is not as foolproof as an air gap. However, it will certainly do the trick if you are concerned about the length of your dishwasher drain hose.

Don't want to do it yourself?
Get free, zero-commitment quotes from pro contractors near you.


Wrapping It Up

If you believe that your dishwasher drain hose may be too long, it’s very likely that it wasn’t installed correctly initially. High loops are common, inexpensive to install, and have proven to be successful at backflow prevention. It will get your dishwasher drain hose off of the floor and mediate your worries about it being too long. On the other hand, if you don’t have enough clearance under your counter, you can opt for the more reliable air gap solution.

Related Guides

Jessica Stone

Jessica considers herself a home improvement and design enthusiast. She grew up surrounded by constant home improvement projects and owes most of what she knows to helping her dad renovate her childhood home. Being a Los Angeles resident, Jessica spends a lot of her time looking for her next DIY project and sharing her love for home design.

Recently Published