Size of Dishwasher Drain Hose  


If you’ve ever owned a dishwasher, you’ve almost certainly also owned a dishwasher drain hose. This is a part you probably haven’t paid too much attention to when it’s working properly, yet it’s essential for a dishwasher to operate. The drain hose is exactly what it sounds like – it’s the conduit through which dirty water flows out of your dishwasher.

So, what’s the size of the average dishwasher drain hose? The average dishwasher drain hose size is about five-eighths of an inch in diameter and the average length is somewhere between ten and twelve feet long.

This isn’t the only line in your dishwasher, though. The other line – the one that brings clean water into your dishwasher – is your water supply line. It is about half an inch wide and about ten feet long.

Drain Hose Specifics

If you’re interested in more than just the size of dishwasher drain hose set-ups, it might be a good idea to look at how and why these drains are so important. After all, they’re an important system that needs to function well if the entire dishwasher is actually going to accomplish its purpose.

Purpose of the Drain Hose

If you’ve ever set up a dishwasher, you know it has to be hooked into your clean water supply in order to work. What you might not remember, though, is that all of that water has to go somewhere. It cannot merely flow back into the water line because this would contaminate your water supply – that’s why it has to go through a drain hose. The dishwasher has to be set up in a very specific way to ensure that the used water goes where it’s meant to go, though.

The Two Main Drain Hose Set-ups

While there are a few different options out there, most dishwashers either make use of a high-loop set-up or an air gap. Each of these setups impacts how the drain hose works and how it’s positioned, but they both help to ensure the safety of your water supply. Choosing between the two requires knowing a bit about how they both work and a bit about how to set up each system.

Note that depending on the state or province that you are located within will dictate which type of drain system you will have to use.

What is a Dishwasher High Loop?

A high loop set-up makes use of basic principles of gravity to ensure that water doesn’t get stuck in your drain hose. A high loop is basically what it sounds like – a set-up that lifts the drain hose up so that water is forced to flow down naturally instead of settling. This keeps the water from getting stuck and flowing back into your dishwasher and ultimately back into your clean water supply.

High Loop Installation Check List

The good news about a high loop is that you really just need 3 simple parts:

  1. The drain hose
  2. Stainless steel clamps (two of them)
  3. something to secure the hose to the bottom of the counter top

There are drain hoses that you can purchase that are specifically designed to be used a a high loop.

Your goal is to place the drain hose as high up as you can. The hose “loop” which is really the elbow needs to be higher then the P-trap. It’s vital that you install it in the right place because a failure to do so is going to negate the usefulness of this type of set-up.

High Loop Installation Steps:

  1. Connect the proper sized drain hose drain hose to the dishwasher (the should be a circular fitting coming out from the sump pump)
  2. Secure the hose with a stainless steel hose clamp around the end that is connected to the dishwasher
  3. find the right place under the counter to secure the drain hose (you can use tape, a hook etc., to secure the hose)
  4. Now connect the drain hose either directly into the garbage disposal or into the drain line above the p-trap
  5. Use another stainless steel hose to clamp the other end of the drain hose to the drain/garbage disposal

What is a Dishwasher Air Gap?

The air gap is a mechanism that makes sure that no dirty water will flow back into the dishwasher after it drains. It is very commonly seen as a small, cylindrical fixture that sits parallel to a faucet.

It should be noted that the air gap set-up is one that tends to be universally allowed by building codes. In certain states like California it is actually required by code. Virtually every part of the United States allows this kind of set-up, as do most other countries. If you’re looking to install a dishwasher you must check to see if this is a requirement.

Air Gap Installation Check List

Much like the high loop method the air gap drainage method does not require a lot of parts. The air gap requires the following parts:

  1. Drain hose (ensure that the hoses will fit on the nozzles of the air gap)
  2. Stainless steel hose clamps (four of them)
  3. Air gap

Air Gap Installation Steps:

  1. Locate the area on the sink to place the air gap
  2. Measure from the dishwasher (where the drain hose connects) to the air gap
  3. Cut the hose to the appropriate length and secure the hose to the dishwasher sump pump
  4. Use one of the clamps on the hose that is connecting to the dishwasher
  5. Measure the distance from the air gap to where you will connect the hose to the drain or garbage disposal
  6. Cut the hose and connect it to the air gap and use another hose clamp

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