What not to flush with a septic system.

A septic tank works because bacteria break down human waste and toilet paper, solids settle, and the clearer water flows out to the drainfield. Anything that does not break down, floats as a greasy layer, or kills those bacteria makes the tank fill faster, clogs filters and pumps, or ends up in the drainfield soil. The rule is simple: only human waste and toilet paper go in the toilet.

Never flush these

• Wipes of any kind, including ones labeled “flushable”. They do not break down in a tank and are one of the most common causes of clogged lines, filters and pumps we find.
• Paper towels, tissues and napkins. They are made to hold together when wet.
• Feminine products, tampons and applicators.
• Condoms.
• Diapers and diaper liners.
• Dental floss and hair. They tangle with other material and wrap around pump parts.
• Cotton swabs and cotton balls.
• Cat litter, even “flushable” litter.
• Cigarette butts.
• Medications. Use a pharmacy or law-enforcement take-back program instead.

Never pour these down a drain

• Cooking grease, fats and oils. They float to the top of the tank as scum, clog the outlet and coat the drainfield. Let grease harden and put it in the trash.
• Coffee grounds. They do not break down and add to the sludge layer.
• Paint, solvents, thinners and stains.
• Motor oil, antifreeze and gasoline.
• Pesticides and weed killers.
• Large amounts of bleach, drain cleaners or disinfectants. Normal household cleaning is fine; dumping a gallon of bleach or a bottle of drain opener can kill the bacteria the tank depends on.
• Water softener backwash, if you can route it elsewhere. Ask us or the county about your system.

What about the garbage disposal?

A garbage disposal sends food solids straight into the tank. They do not break down as fast as human waste, so the sludge layer builds up much faster. Many households with a disposal need to pump noticeably more often than those without one. If you have one, use it sparingly, scrape plates into the trash or compost, and keep grease out of it entirely. We measure the sludge at every pumping and can tell you whether your schedule should change.

Laundry and water use

Septic systems do best with a steady, moderate flow. Doing five loads of laundry on a Saturday sends a surge through the tank that can push solids out to the drainfield, and on a pressure system it can set off the alarm. Spread loads across the week, fix running toilets and dripping faucets, and consider a lint filter on the washer: synthetic fibers from clothing do not break down.

Do septic additives help?

For a normal household, no. Additives do not replace pumping, and some can push solids into the drainfield. Washington’s Department of Health regulates septic additives, and none of them removes the need to have your tank pumped and inspected on schedule. Read more in do septic additives work?

Safe everyday habits

• Use ordinary toilet paper; you do not need special “septic safe” brands, but avoid very thick quilted paper if you have had clogs.
• Normal amounts of household cleaners, dish soap and laundry detergent are fine. Liquid detergents are gentler on systems than powders with fillers.
• Keep a small trash can in every bathroom so nothing ends up in the toilet by default.
• Pump on schedule. See how often to pump a septic tank.

Already flushed something?

If a wipe or other item caused a backup, cut water use and call us. We can jet or camera the line between the house and tank, clean the filter, and pump if needed. See sewer line jetting and 24/7 emergency service. Members of our Septic Maintenance Plan pay no emergency fees.

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