Top 10 Items To Avoid Putting In Your Septic System

By Robert Robillard on Home Maintenance, Plumbing

Caring for Your Septic System

If you have a septic system in your home, you need to be very careful about what household products you use. Septic systems rely on bacteria to break down wastes and solids, but these bacteria need a specific environment to survive. If you put the wrong kind of detergent in your washing machine or you use the wrong drain cleaner, you can end up killing the bacteria, rendering your septic system ineffective. This can lead to overflows, clogs, flooded drain fields and even groundwater contamination. Avoid these common household products to keep your septic system functioning properly.

sink drainMedicines

When you have leftover medications on hand it can be tempting to flush them away. DON’T. Pharmaceuticals can destroy the bacterial balance in your septic system, causing septic failure. They also contribute to the proliferation of “super-bugs”, antibiotic-resistant bacteria that pose a health risk to us all.
Improperly disposed medications contaminate groundwater, endangering the environment and, closer to home, your own drinking water. This is a widespread problem — researchers have found traces of pharmaceutical drugs in the drinking water supplies of 40 million Americans. Pharmaceuticals were found in 80% of rivers and streams sampled in a
nationwide study in 2000.

To safely dispose of medications

Find a medicine take-back program in your area. The U.S. Drug Enforcement Administration (DEA) hosts National Prescription Drug Take-Back events, setting up collection sites in communities nationwide for safe disposal of prescription drugs. Your local police department may also sponsor a medicine take-back program. If you can’t find a medicine take-back program, contact your local waste management authorities to learn about medication disposal options and guidelines for your area.
If you cannot find a take-back program, you may have to dispose of unwanted medications in the trash – but be sure to do it safely to prevent accidental poisoning or environmental contamination. The FDA recommends taking medications out of their original containers, mixing them with an “undesirable substance” (such as kitty litter or used coffee grounds), putting the mixture in a Ziploc bag or a container with a lid, then throwing the whole package in the trash.

Non-Septic Safe Toilet Paper

Other than a septic safe toilet paper, nothing other than human waste should be flushed into your septic tank. It is important to use a toilet paper that is biodegradable and will dissolve quickly. Look for “Septic Safe” on the package. Consumer Reports did testing in March 2014 on 21 brands for softness, strength, and tearing ease and two stood out: White Cloud 3 Ply Ultra and Charmin Ultra Strong, though the Charmin did not dissolve as quickly.

“Flush-able Wipes” and other Clogging Hazards

Although sold as being flush-able, flush-able wipes are anything but; they can take over 10 minutes to break apart and are a high clog risk.

Laundry Detergents

A large part of the volume in your septic system may come from your laundry. Most of the laundry detergents that you find at your local grocery store probably contain some environmental contaminant.

sink drain

Look for:

Low Suds or Biodegradable:

Surfactants are foaming agents and are in all soaps and detergents. They reduce the surface tension of fluids allowing them fluid to flow more easily between solids, freeing dirt from surfaces. They unfortunately affect cell membranes and microorganisms and will damage the bacteria colony in your septic system. Luckily, they degrade quickly and don’t pose a severe threat to ground water.

Low or no phosphorous and nitrogen:

Thankfully, nutrient polluters such as phosphates and nitrates are finally being eliminated from the detergents we use as they promote the growth of choking algae and weeds in our ponds, lakes, streams, and rivers.

Chlorine free:

Chlorine bleach is highly toxic and should be avoided or used in limited amounts when needed, unfortunately chlorine bleach is used in many cleaners and disinfectants. Better alternatives are Oxygen based bleaches for laundering and white vinegar for disinfecting.

Antibacterial Soaps

Antibacterial hand soaps and any product claiming to be antibacterial should be avoided, not only because of the obvious harm they could do to the bacterial colony your septic system needs to function, but they are now being linked to the development of antibiotic resistant “super-bugs”. Good old soap and water works fine.

Automatic Toilet Cleaners

Not only do the antibacterial chemicals in automatic toilet cleaners kill the bacteria in your toilet, they also kill the bacteria in your septic tank. If you use these toilet cleaners, you may
find yourself ending up with a septic tank full of blue water and a lot of dead bacteria. Cleaning the toilet instead with a combination of baking soda and white vinegar will give you
equally effective frothy results that are nontoxic.

Dishwasher Detergents

Dishwasher detergent is more likely to contain phosphates and surfactants than laundry detergents; these are deadly to the bacteria in your septic tank. These chemicals can also
pass through your septic tank to the drain field and eventually enter the soil, leaching into ground water and putting you at risk for contaminated drinking water. Look for and use Phosphate Free detergent.

Drain Cleaners

Drain cleaners are a no-no for all homeowners, even ones who don’t have septic systems. Not only can chemical drain cleaners kill the good bacteria in your septic tank, they can also
eat away at your pipes! The caustic soda or lye used in them is a powerful oxidizer and can cause severe burns. If your drains are clogged, you’d be much better off paying a little more
to hire a plumber to unclog them than using a chemical drain cleaner. If trouble arises, you’ll end up paying a lot more for the damage than you would have if you had hired a

DIY Drain Cleaner:

  1. Pour boiling water down the drain
  2. Add 1/2 cup baking soda, let sit for a few minutes.
  3. Add 1/2 cup white vinegar mixed with very hot water. Let sit for a few minutes. This will cause a chemical reaction – lots of foaming — so cover the drain with a plug or rag. The mixture will work to break down any fats into salt and harmless gas.
  4. Flush with boiling water.

Bath Oils

Putting a bit of baby oil in your bathtub may leave your skin feeling ultra-soft when you get out, but it’s not such a great option for your septic tank. Once it washes into your septic tank
the oil forms a layer of scum that coats the floating waste. The bacteria are then unable to penetrate the oil, preventing it from breaking down the waste. The oil can also clog your
drain field.


Never flush paints, solvents, pesticides, oils, or anything inorganic as they will kill the bacteria or clog the lines.

Other Unsafe  Septic Items – Things not to flush include

  • Disposable diapers
  • Sanitary napkins or tampons
  • Paper towels or bandages
  • Dental floss
  • Condoms
  • Hair
  • Cigarette butts
  • Coffee grounds
  • Kitty litter
About the Author:
Steve McGonagle of Septic Genie helps homeowners diagnose and solve their septic problems. Patented in 1995, the Septic Genie system has helped thousands of homeowners restore their
failed septic systems, avoiding the high cost to “dig and replace”. Septic Genie – Trouble-free septic for life.
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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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