If you’ve just bought a new dishwasher you might have noticed the drain hose is very long. Maybe too long? Don’t worry, there is a good reason dishwasher drain hoses are long. The extra length makes sure you have enough hose to meet state installation rules to stop dirty water from flowing back into your dishwasher.
If your dishwasher drain hose seems to be too long it is probably because you need to install an air gap and a high loop system. By using these two simple techniques you can ensure your dishwasher does not have dirty water flowing back into it.
Dishwasher Drain Hose: Why It Is Important
The drain hose is what connects the dishwasher to the sink. The dishwasher drain hose is usually long (6 feet is standard) so that it can be properly positioned with the appropriate backflow prevention techniques. Although 6 feet is standard, some drain hoses can reach up to 10 feet once they have attachments on. Of course, it is possible the hose is simply too long because your sink and dishwasher are in close proximity to one another. However, we recommend checking if you have a high loop and an air gap installed.
The high loop takes the hose from a low position to a position that is higher than both the sink drain and the dishwasher’s water level and then back down to a low position again. This is important to stop dirty water from flowing back into the dishwasher.
If the dishwasher drain hose is incorrectly installed it can lead to a range of issues. Usually, a properly installed drain hose will not appear to be too long. With this in mind, it is always worth checking the installation method if you notice there is lots of drain hose left over.
Dishwasher Backflow: How Does it Work?
If the dishwasher is not plumbed properly you may experience backflow. This is when the dirty water is able to flow backwards and contaminate the supply of clean water. If there is a point where wastewater and clean water could meet it is a cross-connection. In the event of a change in pressure the cross-connection could experience backflow. For example, a blocked kitchen sink can cause dirty water to end up in your dishwasher because of the cross-connection.
Installing the dishwasher drain hose with an air gap is one way to prevent backflow. The air gap separates the hose to remove the cross connection point. This means the clean water and dirty water never meet. With the two separate pathways the hose that runs clean water remains separate from the hose that deposits dirty water. This means there is no way of the wastewater getting back into the dishwasher.
Guidelines and State Requirements on Drain Hose That is Too Long
Each state has its own requirements related to the installation and connections of dishwashers. Many states require the dishwasher to have an air gap installed but some states require both an air gap and a high loop.
You can find out what your state requirements are by simply checking residential codes online. As an example, South Carolina requires a dishwasher is protected against backflow by an air gap.
If your dishwasher drain hose is too long, the chances are it isn’t installed properly. Although it may seem like the hose should simply connect from A to B there are two key techniques that help prevent backflow. Including these techniques in your installation will likely use up the “extra” drain hose. With that said, sometimes there could be too much hose because the manufacturer needs to ensure you have enough hose to adhere to state rules. They also don’t know how far your dishwasher is from the sink so you could have extra drain hose because of this too.
What is a Dishwasher Air Gap and Do You Need It?
A dishwasher air gap prevents wastewater from flowing into the dishwasher via backflow. It’s a simple solution that makes sure wastewater doesn’t re-enter a clean water supply. The last thing you want is to put your dishwasher on to clean the dishes for dirty water to flow in meaning the dishes come out dirtier than when they went in.
A dishwasher air gap is recommended as it is an effective way to stop wastewater from contaminating your dishwasher. It is the only way to guarantee wastewater won’t end up in your appliances. Plumbing code sometimes requires dishwashers to have an air gap. So not only is it recommended anyway, it might be required. For example, California, Minnesota, Washington and Hawaii all require residential dishwashers to have air gaps.
How to Install a Dishwasher Air Gap (5 Easy Steps)
Step 1. Locate the Air Gap Hole
Firstly you need to find the air gap hole in the worktop. The majority of counters have a pre-cut hole already. A flat vanity disc may be covering the hole. If you cannot find the air gap hole, you will need to drill a hole in the countertop measuring 1-3/8”. The hole needs to be close to the sink edge.
Step 2. Connect the Dishwasher Drain Hose to the Air Gap
Take the drain hose and connect it to the small side of the air gap. Once you connect the hose and the end of the air gap you can use stainless steel hose clamps to fasten the tube.
Step 3. Connect the air gap to the drain hose
To connect the air gap to the drain you will need a Y-brand tailpiece. The tailpiece connects the drain to the sink. A 7/8″ piece of tubing will then attach from the air gap to the tailpiece. Fasten the tube in place with a hose clamp.
You can also connect the air gap to the garbage disposal if preferred. For this, you need to find the tube coming out of the garbage disposal. Attach the air gap to this with the tubing, fastening it with a hose clamp. Make sure the tube is free from bends.
Step 4. Place the Air Gap In the Counter
Now you need to place the air gap through the counter hole from below. Thread a nut to secure the air gap to the counter. Once the air gap is secure, use a wrench to fasten it tightly. Finally, replace the vanity cover onto the countertop hole.
Step 5. Run a Dishwasher Cycle
With the air gap now installed, turn on the dishwasher. Look for leaks in the tube connections and air gap. There should not be any water coming through the air gap, drain or garbage disposal.
What is High Loop and How Does It Help?
A high loop is another method that prevents backflow from running into the dishwasher. This is a simple technique that requires the drainage line to run up to a high point and then back down. The high loop should be a minimum of 32” above the kitchen floor to be effective.
The high loop is a proven technique that helps to stop backflow. However, it is not as effective as an air gap. This is particularly true if there is not enough clearance between your kitchen floor and under the counter to create the drastic slope required in a high loop set up. If your dishwasher drain hose is too long this is a really simple way to deal with it while also improving the set up of the dishwasher.
Drain Connection Using High Loop to Garbage Disposal
Step 1. Pull the Drain Hose Under the Sink
Firstly, you want to gather the drain hose under the sink so you can use it to create the high loop system.
Step 2. Put the Hose in a High Loop
You need the drain hose to go from a low position up to the highest position it can go. Use a pipe clamp to secure the pipe under the sink in the highest position possible.
Step 3. Connect the Drain to the Garbage Disposal
Finally, you need to use a hose clamp to connect the drain hose to the garbage disposal. That’s it! The drain and garbage disposal now connect with a high loop system.
High Loop vs Air gap: Which one is the better option?
An air gap is the best option as it guarantees wastewater won’t flow back into your appliances. A high loop is an effective prevention method but the air gap is foolproof.
Can you shorten dishwasher hose?
The best way to shorten a dishwasher hose is by installing a high loop or an air gap. Dishwasher hoses are longer for a reason so never cut it down.
As you can see, it is normal for dishwasher drain hoses to be long. They may seem too long at first but this is simply to make sure you have enough material to include an air gap and still reach the pipe from the dishwasher to the sink. We recommend including both an air gap and a high loop to keep your dishwasher free from dirty water.