Is Homemade Laundry Detergent Safe for Septic Systems?

Two pump bottles and a jar of homemade laundry products sitting in a basket beside a stack of folded towels.

In a world inundated with synthetic, harmful chemicals, more and more people are choosing to avoid the potential hazards of commercial products by making their own, more natural cleansers for personal care and household cleaning. 

While this is indeed a healthier alternative, often, little thought is given as to where these products end up as they flow down the drain. For those with septic systems, this is well worth considering. 

Is homemade laundry detergent safe for septic systems? Homemade laundry detergents generally consist of all-natural, biodegradable ingredients, which are safe to use with a home septic system. Commonly used ingredients such as natural soap, borax, washing soda, and vinegar will not harm a septic system.

Preventing issues with your septic systems is obviously better than dealing with smelly backups and expensive repairs. 

Knowing what products are safe to use and which ones should be avoided is critical for the health and longevity of your septic system.

What Is Safe to Use With a Septic System?

Sure, there are commercially produced laundry detergents specifically labeled safe for use with septic systems, but they’re often expensive and contain questionable ingredients that many of us do not want coming into contact with our skin or clothing. 

These are two major reasons so many people are now opting to make their own laundry detergent.

The vast majority of homemade laundry detergent recipes use all-natural, biodegradable ingredients which are fine to use with a home septic system. 

In fact, septic tank owners are routinely encouraged to use as many natural cleaning products as possible to ensure that their system continues to function as it should for as long as possible.

Why All Natural?

Septic systems depend on bacteria to function properly. Anaerobic bacteria break down wastes in the septic tank itself, and aerobic bacteria are responsible for the further breakdown of waste in the drainfield. 

If too many bacteria are destroyed, major problems such as clogs, backups, and odors will arise, and no one relishes the thought of dealing with septic issues.

All-natural cleaning agents gently clean laundry without the use of harsh or toxic products that would destroy the very bacteria your septic system needs.

On the other hand, a quick scan of ingredients on many commercial laundry detergents reveals a long list of synthetic chemicals and controversial ingredients.

These chemicals in small doses may be okay to use with septic systems, but they don’t exactly support a healthy environment in which the much-needed bacteria can thrive.

Consider this. Benzene is a hidden ingredient frequently lurking behind the term “anionic surfactants” in many store-bought detergents.

According to the Center for Disease Control, “Benzene dissolves only slightly in water and will float on top of water.”

That doesn’t sound like it would be beneficial for the natural breakdown process of a septic system, does it?

To make matters worse, we are often left in the dark concerning what commercial laundry detergents actually contain. 

For example, I have a bottle of an off-brand detergent that I picked up on sale on a whim to use in my carpet cleaner.

Look at the ingredients: “non-ionic and anionic surfactants, foam suppressor, fragrance, whitener, preservative, and dye.” 

What does this tell me? Well, really nothing useful other than that the manufacturers don’t want me (or you) to know what’s really in it. Pretty eye opening, huh?

Is a Homemade Laundry Detergent Better For Septic Systems?

A septic system is designed to efficiently break down bodily waste and greywater from sinks, bathtubs, dishwashers, and washing machines, not process dozens of chemicals on a daily basis.

With a homemade laundry detergent, you control exactly what is added and therefore, what is emptied into your septic tank.

In this regard, yes, homemade laundry products may be a better option for those with a septic tank. 

Most homemade laundry detergents are made with three basic ingredients: either a liquid or bar soap, borax, and washing soda.

A recipe containing any of these three or a combination of them should pose no problems to your septic system. 

A lot of people like to add Oxiclean to a heavily soiled load or to remove set-in stains.

Since Oxiclean consists of sodium carbonate (washing soda), sodium carbonate peroxide (washing soda and hydrogen peroxide), and detergent, it will break down easily and is safe for use with a septic system.

Adding vinegar to the final rinse cycle is a favorite trick of many of those who like to make their own detergent. Vinegar helps to: 

  • Dissolve product residues.
  • Remove odors.
  • Keep colors bright and whites white.
  • Soften laundry items.
  • Lower the high pH of freshly washed laundry so that it more closely matches the pH of your skin.

Using vinegar in your normal laundry routine should in no way negatively affect your septic system. It can also help with hard water issues, which I discuss here.

You’ll also be glad to know that adding a few drops of essential oil to your homemade batch shouldn’t have a negative impact on your system either.

Of course, dumping oils and grease down your drain is a no-no when you have a septic system, but a few drops of plant-derived oils will be just fine.

What to Avoid With Septic Systems

While most homemade laundry detergent recipes are fine to use with a septic system, there are a couple of products and habits that you will want to avoid.

Bleach

Using chlorine bleach on occasion to brighten a load of whites will generally not harm the actions of septic system bacteria.

You want to use it in moderation though, as too much will cause a mass die off of bacteria and decrease the productivity of your system.

Antibacterial Soaps

Although most of those who make their own detergent tend to use all-natural or homemade soap in their creations, the temptation exists to use antibacterial soap as part of their recipe to further ensure that the laundry comes out of the washer fresh and clean.

Resist the temptation! Antibacterial soaps are designed to kill bacteria.

Unless you enjoy your septic system backing up into all drains inside your house (I’ve been there, done that – definitely not fun!), including your sinks and showers, use an all-natural soap in your recipe (I use castile).

Multiple Loads in a Short Span of Time

Older washing machines can use up to 45 gallons of water per load. While the more modern HE machines only use about half that amount, that’s still a lot of water being dumped into your tank at once. 

Excessive water is one of the leading causes of system failure.

Why? A tank full of water doesn’t allow sludge and scum time to separate and sink down to the bottom of the tank before being drained out through the outlet pipe and into the drainfield.

This often results in clogs and backups.

Whenever possible, spread out your laundry loads over the course of the week instead of doing multiple loads on the same day.

Powdered Versions

Liquid detergents are usually recommended instead of powders for use with septic tanks due to the tendency of powder to not dissolve well in cold water.

This could lead to detergent residue on clothing, but more importantly, the powder may form hard clumps that could clog not only your washing machine, but your pipes and septic system as well.

Salt

Although salt does have stain-removing properties, cleansing power, helps to soften hard water (read more here), and is called for in several DIY laundry detergent recipes, you want to avoid adding an excessive amount of salt to your septic system.

Too much salt in a septic system can cause the sludge in the bottom of the tank to rise and be forced out of the outlet pipe. This leads to clogging and drainfield failure.

Additionally, high salt concentrations in your tank can inhibit the growth and performance of bacteria. Only use sparingly.

Related Question:

Is Homemade Laundry Detergent Safe for HE Washing Machines?

Homemade laundry detergents don’t produce an abundance of bubbles and suds, so they are indeed considered safe for high-efficiency washing machines.

For most loads, you’ll only need about half the amount of detergent that is recommended for regular machines.