Can A Washing Machine Drain Upwards? Here’s When It Works


Buying and taking delivery of a new washing machine can be as simple as paying, receiving, and delivering the unit. There are, however, some circumstances where this is not as simple as it seems, for example, when you don’t have suitable plumbing and you need to employ a plumber to install it.

A washing machine can drain upwards; manufacturers state a minimum and maximum height into which the appliance’s outlet pipes can drain. If the piping is installed too low down, siphoning will occur. Too high up, and the washing machine discharge pump will not have enough power to empty.

Sometimes circumstances dictate the need to have non-standard appliance installations in your home. An example would be if you convert your basement into a laundry and need to find a way of discharging the water from the washing machine.

A Washing Machine Can Drain Upwards

It is possible to drain the washing machine water upwards subject to a few conditions. Two heights are referenced in washing machine handbooks, namely:

  1. The minimum height of the washing machine discharge pipe
  2. The maximum height of the washing machine discharge pipe

The Minimum Height Of The Washing Machine Discharge Pipe

The handbook will list the minimum height of the discharge pipe. The reason it does this is to prevent siphoning from occurring.

When liquid is sucked up a pipe and over the hump, the force of gravity and atmospheric pressure continues to pull the fluid through the tube. This process is called siphoning and means the washing machine will fill and drain simultaneously.

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Siphoning occurs when the drain height is too low or the drain hose is pushed too far down into the drainpipe.

The Maximum Height Of The Washing Machine Discharge Pipe

Check your washing machine manual to determine the maximum height to which the washing machine can drain. Different devices have varying strength drain pumps, and the actual height will vary between manufacturers and between model ranges within a manufacturer.

In the referenced General Electric document, you will see that:

  1. Top load washer outlet pipes must be no less than 30 inches from the floor and no more than 8 feet in height
  2. The outlet drain for the Front Load washer must be at least 24 inches high but less than 8 feet high in total
  3. General Electric and Hotpoint washing machines have powerful drain pumps that pump water as high as 8 feet above the floor
  4. Space maker or Space-Saving compact washers can pump only pump up to 5 feet

If a change to the optimum layout is made, there is always a consequence. Installing the pipe to higher results in a reduced flow rate.

Generally, for every 1 foot the washing machine needs to drain upwards, the flow will reduce by approximately 1 gallon per minute.

Ensure The Outlet Pipes Are Designed To Prevent Backflow

The washing machine forces the water into the outlet and along the drainpipe.

The higher the distance for the washing machine to drain upwards, the more pressure the washing machine pump needs to create.

If you push water vertically up a 1.5-inch pipe for a distance of 8 feet, the weight of the water will weigh almost 0.5 pounds.

It doesn’t sound like a lot, but the washing machine pump must create an additional 40Psi of pressure more, than it would be required for a horizontal connection.

It also means that when the washing machine stops pumping, dirty water will flow back into it!

The other issue is that a continuous 40 Psi is exerted on the washing machine plumbing. Without proper preventative measures, dirty water will flow back into the appliance when it stops pumping.

You need to fit a non-return valve as close to the washing machine as possible to overcome this.

You can find a suitable device on Amazon (like this one for exampleOpens in a new tab.).

It is also helpful if two machines (e.g. washing machine and dishwasher) connect outlet pipes. Without an adequate non-return valve, when one of the machines discharges its water, it will go straight into the other.

When installing, the non-return valve may need to replace the entire washing machine outlet pipe with something sturdier.

At the same time,  you may find the typical washing machine rubber ‘bent’ hose clamps are not strong enough, and you need to replace these with more robust stainless steel crimp pinch clamps.

You May Need To Install A Vent And Trap

If the water drains up to the maximum height of 8 feet and discharges directly into your home’s plumbing network, installing a vent and trap into the outlet system may be worthwhile.

Do Traps Help A Washing Machine Drain Upwards?

Yes, your plumbing system will need traps under every drain. These are P-shaped pipes; they retain some outflow water that blocks any odor entering your home.

Do Vents Help A Washing Machine Drain Upwards?

Yes, vents prevent a vacuum from being created in the outlet pipes, which would empty your traps, making them completely ineffective.

When wastewater is discharged into your home’s drains, gravity carries it into your sewer pipes. If your system has downward sloping pipes, your drains will work because the room’s atmosphere moves the discharge as a vent pipe does.

The problem is that air can travel up your drainpipes, and eventually, the musty washing machine smells may begin to be noticeable. Vent pipes prevent this from happening.

Although most washing machine drainage systems, including vents and traps in the washing machine piping, may be overkill and unnecessary. However, if your going to drain upwards, then these may be necessary.

If you discharge the waste washing machine water in the sink or other pre-existing outlets, these will already have their vents and traps.

If your installation requires a very high outlet pipe for the washing machine to drain upwards, it may be appropriate to install vents and traps as a preventative measure.

Conclusion

Most makes of washing machines can drain the wastewater upward. As long you observe the minimum and maximum heights for the outlet pipe, the device will operate precisely in the way the box says.

If you have a non-standard installation, the manufacturers have built in a small amount of leeway to enable you to adapt the installation according to your needs.

John

I love fixing up my own home and I set up this blog to help others do the same.

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