Dishwasher Supply Line Size (Water Line, Drain Hose, and Waste Pipe Sizes)

Are you installing a dishwasher and wondering about the right supply line sizes?

Look no further! The critical problems are determining the appropriate water line, drain hose, and waste pipe sizes for a dishwasher installation.

The answer is that a dishwasher’s standard supply line size is typically 3/8 inches. Other critical measurements like water line, drain hose, and waste pipe sizes also can be found herewith.

If you’re curious about the details and want to ensure a smooth installation process, read for a comprehensive guide on dishwasher supply line sizes and why they matter.

Gradually, a dishwasher is becoming one of the standard household equipment. Actually, from the U.S energy information administration report, approximately 80 million households have a dishwasher.

In other words, it is a tool that simplifies our lives and helps us save more time as possible, especially with our increasingly busy schedules. Thus, you will have more time to relax or care for other things.

Dishwashers are made of several conjoined parts and usually have different models. Thus, during the installation process or replacement, you can’t pick any item in the market and use it.

There are several things to consider when buying components of a dishwasher machine if you need the item to function efficiently and free from leakages. One of these factors is size compatibility.

What Size is the Dishwasher Supply Line?

The supply line is the metallic pipe, likely made of steel, that supplies water to the dishwasher. One is connected directly to the tap, while the other connects to the inlet.

Thus, it would help if you were careful not to confuse the water supply line and the inlet. Considering that the dishwasher uses principles of pressure in its operations, you must ensure that the supply line is of the recommended length and diameter. 

However, your supply line’s correct size depends on the main pipeline to your home. For instance, if the main pipeline is ¾ or 1 inch in diameter, its supply line size should be ¾ inch, while the other pipes should have a diameter of approximately ½ inch.

In some cases, supply lines of higher diameter tend to cost more. However, that should not make you compromise on the correct size. Otherwise, you will have yourself to blame because of the low pressures experienced by the machine, which will result in poor performance.

What Size is Dishwasher Drain Hose?

The dishwasher drain hose is connected directly to the waste disposal line. Although some people prefer connecting to the gutter, it is not recommended to do so because it is likely to block regularly due to the food remaining.

The standard size for a dishwasher drain hose is ½ inches. It has different-sized rubber boots on one end to allow several connections. As a result, most dishwasher drain hoses can connect ½-inch, ¾-inch, and 1-inch connections.

Since a highly long drain hose is prone to twisting, preventing the correct water flow, installing an extremely long pipe is not advisable. If the pipe is too long, you will have to cut it.

The standard drain hose length in most homes is 7/8 feet. To determine if the length is okay, attach the pipe on both ends using a hose clamp. Afterwards, check for any twists, untwist them, and cut the excess length to prevent blockage.

Nonetheless, drain hoses are prone to clogging even though you got the proper sizing. However, it is not something to cause an alarm because unclogging is relatively easy without twists.

To unclog it, first, remove the utensils from the ranks. Next, switch off the electricity and eliminate the water using a towel. 

What Size is Dishwasher Water Line?

It is important to check the size of the inlet hose if you don’t want the leaking water to fill your room in no time. Besides, having the correct sizing of the inlet hose helps maintain the needed water pressure to keep the machine’s efficiency.

The water inlet sizes usually depend on the model of the dishwasher. However, most manufacturers design their machines to use a ¾ inch water inlet line.

What Size is Dishwasher Waste Pipe?

The waste pipe is connected to the drain pipe. As its name suggests, it carries the waste to the draining area. Thus, besides its size, you must ensure it is robust, especially to rust. Also, you can think about using a plastic waste pipe.

On its size, the most recommendable diameter is ¾ inches. However, you should highly consider the pipe you are connecting with. 

Additionally, you should also check the length of the waste pipe. Ideally, it should be long enough to reach the septic tank or the drainage area.

Do Dishwashers Require a Water Hammer arrestor?

The dishwasher water line has valves that prevent the backward flow of water. However, when the water flowing in the system suddenly stops, it is likely to cause the valves to close unexpectedly, resulting in shock.

As you might be aware, shock is not suitable for the dishwasher. In search of the solution, that introduces us to a water hammer arrestor.

A hammer arrestor is a device that absorbs sudden pressure that results from the sudden closing of water due to a stop in water flow. As a result, this device prevents potential damage.

Consequently, a water hammer arrestor is quite crucial in a dishwasher machine. It will absorb the valve shocks only, but it will also help prolong the device’s lifespan.

However, some dishwasher models do not have the hammer arrestor installed. Besides, even if your device has it, it may need a replacement after three years. Thus, you must learn how to install a water hammer arrestor.

How to Install Hammer Arrestors in a Dishwasher?

The Harmer arrestor absorbs the pressure and shocks caused by plumbing fixtures.

It can be installed vertically or horizontally. Strictly, it should be installed 6 feet next to the valve causing the noise.

• Step 1: Shut off the Water Supply – Disconnect the water hammer arrestor when installing the waterline. Thus, to avoid causing messes, it would be wise to shut off the main water supply in the house.
• Step 2: Drain the Pipes – Before you shut off the main water supply, some water was already flowing into the pipes. Thus, drain this water to prevent it from spilling onto the ground. Turn on the sink tap and wait until all the water has drained.
• Step 3: Disconnect the Supply Line from the Valve – Next, you need to disconnect the supply line of the valve that is causing the noise. Note that the harmer arrestor should be installed at a proximity of 600 feet to absorb the shocks caused by the valve efficiently.
• Step 4: Reconnect the Supply Line to the Harmer Arrestor – Install the water hammer arrestor at the point where you disconnected the supply line. You are free to install the water harmer arrestor depending on the orientation of the supply line. 
• Step 5: Use a Wrench to Tighten – Afterward, use a wrench to tighten the harmer arrestor at 45 degrees. Rotate the harmer arrestor until it is tight to prevent leakages. Do the same with the other opening of the arrestor.
• Step 6: Turn on the Water Supply – Before using the dishwasher, check if you have tightly reconnected the water system. Hence, turn on the main water supply and the tap connected to the dishwasher supply line. 

If you had made the connection correctly, you shouldn’t be leakages. In case of any, you can use the wrench to tighten the pipe connections. 

Also, you can check out this video for a demo of installing the water hammer arrestor. 

How Do I Stop the Water Hammer in My Dishwasher?

Water hammer is usually characterized by the clanging of the water pipes, which causes a shaking-like effect. This effect is caused by sudden water pressure, which causes the valves to close instantly. 

There are several causes of water hammering. They include;

• Loose pipes are likely to cause loud bangs if they are not tight. Thus, you should check for loose joints, bolts, and straps. So, you can check and tighten the strips or, if needed, replace them.
• Clogged air chambers- if the water hammering has started from nowhere, the air chambers are probably clogged. Fortunately, they are easy to unclog. To do this, you need to create new air chambers.
• Fast-acting valves are the apparent cause of water hammers when the water stops instantly, causing the valve to shut off abruptly.
• Worn-out valves- just like other dishwashing machine components, the valves depreciate as the days go. Worn-out valves cannot sufficiently hold the pressure causing the clanging sound. Therefore, you can stop the water hammers by taking action to replace essential ones.

Final Words

The dishwasher machine contains different types of pipes, which should have specific sizes to ensure efficient and mess-free water flow.

These pipes usually range from ¾ inches to 1 inch in diameter. Further, it is essential to check their lengths also. For instance, the drainpipe should not be too long to prevent twisting, hindering efficient water flow.

Additionally, you may need to install water hammer arrestors to prevent the clanging of the pipe.

Fortunately, we have discussed how to do the installations and the sizes required by the dishwasher supply line, drain hose, and waste pipe, among others.

James Miller

James is an organic fertilizer professional who owns a successful organic fertilizer company in new jersey. He is an expert in waste management in both houses and community cases. In his free time, he loves to write about his experiences in the field.