How Many Loads Of Laundry Can I Do With A Septic Tank?

Ossiana Tepfenhart
by Ossiana Tepfenhart
Doing the laundry isn’t fun, but it is necessary and how many loads you can do varies based on your septic tanks. Factors such as the size of your septic tank, the size of the loads, and how much water you use with other fixtures determine how many loads of laundry you can do. The average homeowner’s septic tank can handle 5 full loads, but let’s take a look at how to determine how many loads of laundry you can safely do.

Ah, a fresh batch of laundry. Is there anything better, more satisfying than getting clean clothing after a messy project like priming fiberglass or building a fence? We think not. And while laundry is a must-have for DIYers, there are certain moments where your supplies are going to limit how much laundry you’re able to do. This is especially true with using a septic tank.

The amount of laundry that you can do depends on septic tank size. If you have a 600 square-foot septic tank, the most you can do is a maximum of five full loads of laundry. This doesn’t account for other water-based needs, like using the bathroom or washing dishes.

Doing laundry with a septic tank means that you’re going to have to be delicate with your loading. If you aren’t careful, excess washing machine loads can cause severe backups, flooding, and clogs. If you are new to owning a septic tank, you are going to need to know what to expect. This guide will help.

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How Many Loads Of Laundry Can I Do With A Septic Tank?

As we said before, size is the biggest factor that will play into how many loads you can do. To understand what your septic tank is capable of, it’s best to do the math. Here’s what to expect:

  • On average, a home septic tank covers 600 to 900 square feet of space.
  • Septic tanks can only usually “flush out” 1/3 of the square footage of water in the tank per day. This enough space for 200 gallons per day.
  • A typical laundry load will require 40 gallons of water.
  • This leads to five full loads of laundry without the risk of flooding, not including any other water use in your home.

If you take a look at the conservative side of things, you probably shouldn’t do more than one load on a single day. If you are more liberal, you might be able to get away with three. However, this is a seriously risky idea.

Why Do You Need To Wait Between Each Load?

Septic tanks are meant to separate solid waste from liquid waste. If they don’t have adequate time to let the solids separate, your septic tank may send out solid waste into the drainage area. Or, in some cases, it can cause a flood. This is why most septic tanks need at least a day between laundry loads.

Is There Anything You Can Do To Avoid Septic Tank Flooding?

If you have a septic tank and want to do a lot of laundry, we strongly advise against it. The truth is that it’s better for your tank and your wallet to just hit the local laundromat. With that said, there are things you can do to max out the amount of laundry you can wash. These tips below are known to help:

  • Fill your washing machine to the brim. The best way to reduce the amount of water that’s being used is to make sure you add full clothing loads to your washer. This reduces the amount of water you need to use, and also ensures you get the most of your laundry time.
  • Select the appropriate cycle for the laundry load. For instance, don’t use a cycle intended for a large load if you’re only washing a few items.
  • Don’t run your washers during peak usage times. If you can, try to avoid loading up your washer during times where people usually want to use a shower or bath. This can stress out your septic system and plumbing system, which in turn, puts you at risk for flooding.
  • Consider staggering loads. If you have to do a lot of laundry, consider staggering it over a couple of days. This will allow the tank to properly drain and greatly reduce the risk of your septic tank becoming flooded. While it may be very convenient to get all your laundry done in a single day, this places serious strain on your entire septic system, as the average load of laundry uses a staggering 47 gallons of water.
  • Keep your septic tank properly maintained. Draining your septic tank every three to five years is a must if you want to get the most out of your tank’s efficiency.
  • Switch to a high-efficiency washing machine. If you want to max out the number of loads that you can do, get a high-efficiency washing machine. Some of these models can function on as little as 15 gallons per load. This can effectively double the loads you can do.
  • Avoid flushing non-flushable items down your drain. Disposable wipes, napkins, paper towels, and other similar stuff won’t do much aside from clog plumbing and make it harder for your septic tank to do its job. These materials can also delay your tank’s ability to do its job.

How Can You Tell If Your Septic Tank Is Overloaded?

You’ll usually notice because your plumbing will be laggy. You might notice that your toilet flushes slowly, or that your kitchen sink isn’t quite draining as well as it used to. Outside, you might notice a flooded plain, an odd sewer smell, or pools of water pooling on your lawn. If it gets really out of hand, you might even experience a flood in your basement.

When Should You Just Hit The Laundromat?

If you aren’t sure whether your septic tank will be overloaded, these guidelines will help you figure out what is best for you:

  • You have to do five loads or more over the span of three days. You might be able to squeak in two loads on some days, but this is not advisable. It’s better to give your washing machine and tank a break.
  • You’ve been noticing your toilet flushing slowly. If you are already witnessing signs of septic tank trouble, you should call a maintenance crew and limit your laundry to one load per week.
  • The laundry that you have to do requires multiple heat settings or color divisions. This can mean that you need to choose between your clothing quality and septic tank health. Not a good look.
  • There has already been flooding due to septic tank issues. At this point, it’s no longer a matter of trouble in your septic tank. It’s a clear sign that your tank is practically screaming for help.

When Should You Get Septic Tank Help?

Generally speaking, you should try to call a professional any time you notice your septic tank draining slowly or when you notice flooding in your yard. Along with calling a pro every time you see an issue arise, you should also make a point of scheduling regular septic tank drainage sessions once every three years.

If you’ve been having a particularly hard time with your tank, check the age of the equipment. There is a chance that you may need to get it replaced if it’s over 10 to 15 years old.

Consider Detergent

When you have a septic tank, another important thing to keep in mind as you’re doing laundry is the detergent you use. Your septic tank operates with the bacteria inside. The purpose of this bacteria is to remove harmful contaminants from the wastewater, so it can safely penetrate into the drainage field.

Some cleaners such antibacterial detergents, nonbiodegradable soaps, and bleach can kill these crucial bacteria in the system. While it may be difficult to entirely eliminate the use of household cleaners and similar toxic materials, try to limit the amount that enters your system. Make sure that you are using a detergent that is safe for use with a septic system. In addition to the type of detergent, pay attention to how much you use.

Using an excessive amount of detergent can clog soil pores, leading to poor drainage. To prevent this, avoid using powdered laundry detergent, as they use clay as a “carrier.” The clay in the detergent can speed up solid buildup in the septic tank and possible lead to the disposal area becoming plugged. Always opt for liquid detergent if you have a septic system.

Do You Need a Septic Tank Cleaning or Pumping Service?

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Our Final Take

When you’re trying to set a good laundry schedule, the most important thing you can do is think about your septic tank. Septic tanks need to have their water usage minimized to help them function. This means that most people should avoid doing more than one to two loads of laundry using a traditional washing machine per day.

Of course, there are ways to mitigate the risk of multiple loads per day. Using a water-efficient washing machine is usually the smartest thing you can do. Avoiding flushing unflushable items, regularly maintaining your septic tank, and also avoiding peak hours can help. If you aren’t sure if you’re stressing your washer, just err on the side of caution and hit up a laundromat.

Most people would be a bit bummed to find out that they might need to go to the laundromat, but trust us when we say it’s the lesser of two evils. It costs way less to do a batch of laundry than it does to clean up a flood!

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Ossiana Tepfenhart
Ossiana Tepfenhart

Ossiana Tepfenhart is an expert writer, focusing on interior design and general home tips. Writing is her life, and it's what she does best. Her interests include art and real estate investments.

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