Clothes washing machines vs. the septic system:

Can we use a clothes washer or "washing machine" when a home is connected to a private septic system? What steps should be taken to protect the septic system from excessive water use or clothes lint or detergents? How to extend the life of a septic system.

Washing Machine Draining into Septic System

Article Contents

• WASHING MACHINE IMPACT on SOAKBED or LEACH FIELD
• BEST LAUNDRY DETERGENTS for SEPTIC SYSTEMS
• MINIMIZE EFFECTS of LAUNDRY SOAPS on SEPTIC
• MINIMIZE EFFECTS of LAUNDRY WATER VOLUME on SEPTIC
• EFFECTS of LAUNDRY BLEACH on SEPTIC

[Click to enlarge any image]

Does a washing machine overload and harm the septic system?

The volume of water from home washing machine use should not be a problem with a normal septic system in good working order.

As we discussed at Dishwashers, in some conditions you should avoid emptying washing machine discharge into the septic system:

• Drainfield capacity limits:
  
   If the absorption system (leach field, drainfield) has limited capacity to absorb effluent
• Drainfields near failure: 
  
  If the absorption system is showing evidence of failure, such as effluent coming to the surface of the property or backing up into the building (nonetheless you need septic field investigation and repair)

Below we discuss steps you can take to minimize the possible effects of extra wastewater loads caused by washing machines, and then we discuss the effects of detergents and soaps when operating a clothes washer connected to a septic system or drywell.

Does Washing Machine Detergent Harm the Septic Tank or Septic System Drainfield?

The volume of detergent from a residential clothes washer entering the septic system is so low as to be very dilute when it enters the septic tank, dilute enough that it is not going to harm the septic tank bacteria at normal levels of residential dishwasher use.

Clothes washing machine detergents do not make a high level of suds inside the machine.They rely on surfactants, high water temperature, and time spent agitating the contents of the clothes washing machine to clean them.

However many if not most washing machine (and dishwasher) detergents contain phosphates or nonylphenol ethoxylate surfactants. Surfactants are what make detergents effective in lifting soil particles off of a surface (a dish in the dishwasher or a shirt in the washing machine). These chemicals may be serious contaminants of ground water and surface water in the environment.

What laundry detergents or soaps should we use in a Clothes Washing Machine connected to a septic tank or to a Graywater System?

Sometimes we find that dry powder clothes washer soap appears as clots and clogs in the system - usually because the homeowner is pouring in too much detergent and is not following the manufacturer's instructions.

Passing solid clumps of detergent into the septic tank speed clogging of the system and in severe cases can even block a building drain.

Recommended dishwasher & laundry detergents: are discussed in detail separately

at DETERGENTS in our article

at DISHWASHERS vs SEPTICS where we discuss recommended detergents and also the effects of phosphates & detergents on the environment.

How to minimize the possible clogging or other effects of laundry soaps on the septic system

A private septic system tank and drainfield can be protected from clogging due to excessive use of detergents.

And even if a building's wastewater is carried to a public sewer there may be concerns with detergent clogging in the drain system. In the laundry room serving a residential apartment building such as shown in our photo (left, Bronx, NY), asking residents to follow these suggestions can help prevent sewer drain clogging.

• Avoid using more than the necessary amount 
  
  of powdered laundry or dishwasher detergent. Excessive amounts of powdered laundry detergent often fail to dissolve in the washing machine.
• Liquid laundry detergent:
  
   Safer if you are not the one operating the clothes washing machine, use liquid laundry detergent.
• "Budget" powdered laundry detergents
  
   contain extra amounts of fillers (in some cases montmorillonite clay) which increase the risk of system drainage or drainfield clogging.
• High phosphate laundry detergents 
  
  may be a factor in reducing drainfield life [more data is needed on this point.]
• Liquid detergents recommended:
  
  We prefer to use liquid detergents in the recommended amounts or less in clothes washers connected to or draining into any onsite disposal system, septic tank, cesspool, or drywell.

The following measures may relieve the water volume load on septic fields from the washing machine:

• Use liquid laundry detergent
  
   rather than a dry soap powder laundry detergent to reduce septic system clogging. Some experts report septic system clogging in pipes, septic tank, and drain field when large amounts of dry laundry soap powders are used.
• Install a lint filter
  
   on the washing machine water drain line to avoid sending lint into the septic tank and fields or install a graywater filter ahead of your drywell if you are using one to receive washing machine discharge waters. Details are
  
  at FILTERS SEPTIC & GREYWATER
• Install a separate drywell
  
   to receive water from the washing machine drain, and perhaps dishwasher and other graywater.
• Spread out use of the washing machine
  
   over longer intervals - perhaps washing loads in morning and at night rather than running one laundry load right after another. This "dosing" of the septic system or drywell gives the absorption system time to recover between washes.
• Cleaning out the septic tank more often than the minimum
  
   schedule will extend the life of your drainfield. In turn, this will permit the drainfield to better absorb the extra volume of wastewater generated by clothes washing.
  
  Similarly, any other measures that protect the drainfield's ability to absorb water, such as avoiding flooding the fields with surface runoff, become more important if a family is using their washing machine alot.

Also see CHEMICALS & CLEANERS into the SEPTIC TANK?

& CHEMICALS to KEEP OUT OF SEPTICS - separate articles

Effects of Household Bleach on the Septic System

Bleach at normal household usage levels should not harm the septic system.

• Braida, Washington, Say Kee Ong, William L. Smith, and James W. McCabe. "Fate of adsorbable organic halides from bleached laundering in septic tank systems." Environmental toxicology and chemistry 17, no. 3 (1998): 398-403.
  Abstract:
  A study was conducted to assess the fate of adsorbable organic halide (AOX) formed from the use of household bleach during laundering in a septic system.
  
  Experiments were conducted using laboratory-scale septic tanks and leachfield systems. Addition of feed water containing 20% of bleached or unbleached laundry wash water did not affect the performance of the septic tanks or the leach fields.
  
  Overall chemical oxidation demand (COD) and total organic carbon (TOC) removal rates through the septic systems were in the range of 90%. Adsorbable organic halide from unbleached laundry wash water with concentrations between 0.13 and 0.21 mg/L appeared to be removed in the septic tank but not in the leach field.
  
  The average overall AOX removal rate using unbleached laundry wash water was approx. 43%. In contrast, the overall removal rate of AOX generated from the use of sodium hypochlorite in bleached laundry wash water was between 87 and 94%. About one-third of the AOX was removed in the septic tank, and the rest was removed in the leach field.
  
  Analysis of the septic tank sludge and the soil in the leach field showed no accumulation of AOX from the use of hypochlorite, and the AOX was most likely removed by biodegradation and/or chemical degradation.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-08-08 by Donna - tub shower and toilet back up when I wash clothes?

Why do my tub shower and toilet back up when I wash clothes?

On 2020-08-08 by (mod)

Donna:

Some common explanations include:

- a partly-blocked drain thta can't handle the higher volume of wastewater flow

- a failing septic system or cesspool that backs up when you are sending a larger volume of water into it

On 2018-05-27 by Bruce K Bernard - what is causing septic tank drian line blockage?

We are on a septic system. The pipe between the house and the septic tank has gotten blocked several times. When using a snake, big gobs of a white material seem to be causing a blockage. We thought it was grease,

but we are VERY CAREFUL not to put grease down the drain.

A friend told us it could be the laundry detergent. We use a liquid, and don't use too much. Is it possible it's the laundry detergent? What should we use.

On 2018-05-27 - by (mod) -

I don't think liquid laundry detergent would be causing a white greasy blockage in a drain.

More often that's fats or Oils for example from cooking. You might want to have a plumbing company run a sewer line camera through the drain in order to find out if it's damaged, broken, or improperly pitched.

On 2014-08-29 by Andy - my washing machine "drywell" no longer works

I have separate tank for my washing machine. It is actually aplastic drum with no bottom. After 5 years the bottom is covered with soap scum and the water will not drain out. Is there a chemical that I can put in the drum that will remove the soap scum?

On 2014-08-30 - by (mod) -

Andy,

Though there are caustics that can break up soap scum they are harmful to the environment and probably illegal in your area. A better drywell or soakpit design for a washing machine water disposal system allows water to disperse into the soil not just from the bottom of the pit but through the sides as well. Details are at

DRYWELL DESIGN & USES 

Meanwhile you might be able to get some temporary improvement by pumping and cleaning the existing installation or by disturbing its bottom layer mechanically.

On 2012-11-08 by Smitty - recommended detergents for an aeration system?

what are some recommended detergents for an aeration system? I have seen too many confusing lists.

On 2012-11-08 - by (mod) -

Smutty,

Stick with liquid detergents if you can, and be sure to use no kore than the manufacturer's recommended detergent quantity per wash load. The chief problem i know of is overdosing detergent and solid detergent clogs from using too much.

 

On 2012-11-06 by Lanaye - husband's body wash causing bubbling septic?

I'm using he detergents and biodegradable also on my septic system...but my husband gets a little carried away with BODY WASHES in the shower.

too many bubbles going into septic? we just finished clearing up a HUGE detergent clog when we had the tank pumped a few weeks ago! Took us 3 days of "perseverence"

On 2012-11-06 - by (mod) -

Marital advice from InspectApedia

Let your husband wash with whatever he likes in the shower. Unless someone is literally pouring bottles of soap down the drain I'm doubtful that it's going to explain a septic tank or system failure;

Detergent clogs are generally traced to solid detergents (and their over-use in a washing machine) not to liquid soaps.

 

On 2012-09-11 by Donna - ventless washer dryer sends lint into septic?

I'm wondering if a ventless washer/dryer combo is a bad idea, since dryer lint could potentially end up in the septic field. Any idea how effective the lint filters built into these appliances are?

On 2012-09-26 by Ron Jackson - how does dryer link get into the septic system?

How would dryer lint ever make it to your septic tank let alone your drain field? Do you mean to say the lint remaining within the wash water?

On 2012-09-27 by mod

Ron, I agree. About the only way clothes *dryer* lint from a conventional clothes dryer would get into the septic system would be if someone foolishly pulled lint out of the dryer and flushed it down a toilet.

However, washing machines, too, produce a lot of (wet) lint when cleaning clothes - that lint, if not screened in the washer, can get into the septic system.

Donna if you could give me the brand and model of your combination unit I will research how filters work on those units.

On 2012-08-13 by Maria Mutnansky - I make my own laundry degergent from naptha

So... in order to be more economical I have been making my own liquid laundry detergent. This, however, is made from powdered ingredients. Fels Naptha soap which is "melted" in hot water first, washing soda and borax. I have to say it IS way cheaper.

BUT for about 4 months now, or maybe even longer, we have had a horrible smell (intermittent, not constant) which smells like sewage. We'd had a break in our toilet line, it was fixed... but then the toilet wouldn't flush at all... my husband snaked it and suddenly we had this horrible odor about every evening, but mostly in the evening. I had the tank cleaned (and you know that isn't cheap).

Still, a bad odor. Recently the company which has a "contract" to inspect our tank came out and said everything was fine (we were not home when they came... so we could not ask questions... very annoying).

So is there any chance my stink could be caused by buildup from my detergent?

And if so, how do I get rid of it... and if not, what in the world could be causing the stink? Oh, and the aerator was giving us some trouble (yes, days after they checked it) but when we got it going again the smell was SO intense and bad.

Is there something between the piping and the toilet which should be prohibiting smells from coming up? I don't have a lot of money to spend on this, but I need to find some answers.

...

Continue reading  at WATER SOFTENER IMPACT on SEPTIC or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see WASHING MACHINES & SEPTIC SYSTEMS FAQs - questions & answers posted originally at the end of this page.

Or see these

Recommended Articles

• TOILETS, DON'T FLUSH LIST - home
  • NEVER FLUSH INTO SEPTICS
  • CHEMICALS to KEEP OUT OF SEPTICS
  • CHLORINE IN SEPTIC WASTEWATER
  • DISHWASHERS vs SEPTICS
  • GARBAGE GRINDERS vs SEPTICS
  • GARBAGE GRINDERS on SEPTIC or SEWER
  • REVERSE OSMOSIS CONCENTRATE DISPOSAL
  • SEPTIC TREATMENTS & CHEMICALS
  • TOILET TISSUE CHOICES
  • WASHING MACHINES & SEPTIC SYSTEMS
  • WATER SOFTENER IMPACT on SEPTIC

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WASHING MACHINES & SEPTIC SYSTEMS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to SEPTIC SYSTEMS

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