Does A Washing Machine Need a Backflow Preventer? (Explained!)

Imagine your washing machine’s wastewater going back into your main household supply! It must be disgusting, right? Well, that’s why backflow preventers are essential. But does a washing machine need a backflow preventer?

Ordinarily, washing machines have built-in anti-backflow mechanisms and join the sewer through standpipes, eliminating the need to fit backflow preventers. But since none of these options guarantee 100% protection against backflow, there’s a need for backflow preventers.

A proper backflow preventer will keep the polluted laundry water away from the household water, which means protection against possible harmful chemicals, among other threats.

This post will help you understand what backflow preventers are, how they work, their benefits, and their types. But before that, let’s talk about the problem, backflow.

What’s backflow exactly, and what causes it? Let’s answer that next.

Does a washing machine need a backflow preventer

What’s Backflow?

Backflow is a common plumbing term that refers to the contamination of clean water by wastewater that moves reverse direction.

In the case of the washing machine, it’s when the washer’s wastewater goes back to your household storage and contaminates it. The water you’ll drink, cook with, and wash will have contaminants from the wastewater in the long run.

What Causes Washing Machine Backflow?

The two primary causes of backflow are:

  • Back Pressure

Backpressure refers to when the wastewater pressure exceeds that of the freshwater (incoming) water supply.

That’s likely to happen in a high-pressurized system like a pump, boiler, or elevated tank. And in the case of washing machines, power washers can suffer backpressure.

  • Back Siphonage

Back siphonage refers to a sudden drop in pressure that causes wastewater to move in the reverse direction, contaminating clean water. That usually happens when there is a significant breakage in your main water supply.

What Is a Backflow Preventer?

A backflow preventer refers to a device that encourages one-direction flow. As the name suggests, this device does not allow the movement of wastewater backward, which means your household water is lower.

Today, backflow preventers come in different types, but here are the most typical kinds:

  • Atmospheric vacuum breakers (AVB)
  • Check Valves (non-return valves)
  • Air gaps

Let’s discuss the three options below.

How Does a Washing Machine Backflow Preventer Work?

While a backflow preventer’s job is to discourage the reversal flow of wastewater and protect your domestic water supply from contamination, their mechanisms of action differ among the various types, as shared below:

Atmospheric Vacuum Breakers (AVB)

AVB backflow preventers are common on faucets and hoses, and they have a valve that opens up when the pressure drops. When the valve’s air vent opens, it interrupts the vacuum and seals off the main water supply utterly.

As a result, there’s no back-siphonage when the pressure drops in your supply line. It’s essential, however, to install a PVB backflow preventer at least 6 inches off the ground surface to effectively stop backflow.

The only downside is that these devices are not effective against consistent water pressure.

One example of an ABV that you can install to prevent laundry wastewater backflow is the TS Brass B-0968-RK01.

This brass AVB meets all the basic industrial standards to promise protection against backflow. Since its brass construction, it promises to serve you longer by resisting rusting.

washing machine backflow preventer

Check Valves (Non-Return Valves)

Check valves, which some manufacturers call non-return valves, are small anti-backflow devices that promote the one-direction flow of water in response to pressure changes.

When the pressure increases during water discharge, check valves open, and when it reduces, they close to prevent backflow.

Unlike AVBs, check valves are ideal for continuous water pressure, and you can fit them on an individual outlet or service center.

Furthermore, you can install them vertically or horizontally. The Camco 233031/2¨ Backflow Preventer is one bestseller check valve for your consideration. This lead-free brass check valve promises durability and water safety, making it one of the most reliable.

Air Gap Backflow Preventer

An air gap backflow preventer creates an air gap seal, as the name suggests, to prevent backflow. These backflow preventers are widespread among dishwashers instead of laundry washing machines.

They are pretty inexpensive and come in a variety of finishes. These devices work by separating the clean water hose from the wastewater hose.

One perfect example which is best for dishwashers is the Moen 105895BL Air Gap.

can water backflow into washing machine

Other backflow preventers that are popular in industrial and pharmaceuticals settings include:

  • Reduced Pressure Zone (RPZ) Devices
  • Hydrostatic Loops
  • Flood Gate Valves

Does A Washing Machine Need a Backflow Preventer?

Now that you know what a backflow preventer is, the obvious question is, do you need the anti-backflow device?

There are two reasons why a backflow device may be unnecessary for washing machines. First, washing machines have built-in anti-backflow mechanisms that prevent the reverse flow of discharged water.

Secondly, washing machines usually drain into the sewer line through a standpipe, a drainage option that prevents backflows if well-fitted and of the correct size.

The question, however, is, how effective are the two options?

Let’s start with the built-in anti-backflow device. The problem with this device is that it does not guarantee 100% backflow prevention. Issues like backpressure and siphonage, which I mentioned earlier, could cause a backflow.

In the second case, when you miscalculate the standpipe’s length or go for the wrong diameter, there’s always the risk of backflow.

So, installing a backflow preventer is advisable to reduce all these risks and assure one-way wastewater discharge.

washing machine drain backflow preventer

Let’s now discuss the benefits of fitting this anti-backflow device.

Here are the benefits of washing machine drain hose backflow prevention using backflow preventers:

1. Water Safety

Backflow is a health hazard. The wastewater that finds its way back to your domestic water supply during a backflow carries toxic chemicals and pathogenic microbes, which are a health risk.

But with a backflow preventer, that doesn’t happen, which means your water is safer.

2. Clean Pure Water

You don’t just enjoy the safe water but also one that is free from discoloration and bad smell. A backflow preventer stops contaminants that could discolor or make your water smelly.

So, whether you choose to drink or wash with our water supply, you don’t have to fear unpleasant smells or colors.

3. Legal Compliance

Having backflow preventers is a legal requirement in a majority of states. That includes South Carolina and Louisiana.

In these states, you need to install a backflow preventer to protect the state’s public water supplies from contamination.

Failure to comply with the regulation could see you face prosecution. So, to be a law-abiding citizen, it’s wise to install this feature.

4. Avoid Expensive Repairs

Backflow doesn’t just pose a health risk, but it can also damage your plumbing work. You are likely to suffer recurrent repairs when the backflows are recurrent.

But once you stop them by installing a backflow preventer, you cut down on the repair costs.

What Are the Downsides of Backflow Preventers?

One major downside of backflow preventers is that their installation is a messy job. You should be ready to roll those sleeves and do the dirty job.

The other thing is that installation is not easy. You may need to hire an expert, which negates the first concern. But now, you’ve to get into your pocket to pay for the expert and buy the device.

But as you can tell from my recommendations above, these anti-backflow devices are inexpensive. You won’t spend more than $30 on one.

People Also Ask

1. How Do I Stop the Backflow On My Washing Machine?

You can stop a backflow on your washing machine by connecting its drain hose with a taller standpipe, at least 36 inches, by getting rid of knots and kinks from the drain hose and unclogging the drain.

But still, you can have an easy time installing a backflow preventer that promises better backflow prevention. This anti-backflow device, which you can buy online or at most hardware stores, promotes only one-direction wastewater flow, preventing reversals.

2. Can Water Backflow into Washing Machine?

If there’s back pressure or a back siphonage, water backflow may end up in your main water supply, where your washing machine will pick it, given that your main household supply feeds it.

For that reason, it’s advisable to connect your washer’s drain properly to the standpipe and, if possible, fit a backflow preventer.

3. Do Washing Machines Have Backflow Preventers?

Washing machines usually have built-in anti-backflow devices that protect them from backflow. However, they don’t guarantee 100% backflow protection.

You may have to install a commercial backflow preventer to promote better backflow protection.

4. Do Washing Machines Have a Non-Return Valve?

Since washing machines have built-in anti-backflow features, they don’t require a non-return valve. That, however, doesn’t stop you from fitting one. After all, a non-return valve promotes one-direction wastewater flow, preventing backflow.  

5. What Is a Backflow On a Washing Machine?

Backflow refers to the reversal of discharged water back into your main water supply. A backflow contaminates your main water supply, making it unsafe, discolored, and smelly.

6. Do You Need to Install a Backflow Prevention Device?

If you want the assurance of 100% backflow prevention, then you need to install a backflow prevention device.

However, domestic washers have built-in anti-backflow features that discourage backflow. Sadly, not all are 100% effective in isolating discharged water from portable water.

In Summary – Does A Washing Machine Need a Backflow Preventer?

Given the importance of a backflow preventer in promoting one-way wastewater discharge and protecting your household’s main water supply from contamination, there is no denying you need it for your washing machine. You need it to supplement your washer’s built-in anti-backflow device and standpipe.

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