What Not to Flush With a Septic System

Short answer

With a septic system, flush only human waste and toilet paper. The EPA says to keep wipes (including baby and wet wipes), feminine hygiene products, dental floss, diapers, coffee grounds, cat litter, paper towels, grease, medicines and household chemicals out of the toilet and drains. Limit the garbage disposal, avoid chemical drain openers and spread laundry across the week.

Everything that goes down your drains ends up in your septic tank and then in the drainfield. The EPA's SepticSmart program puts it simply: whether you flush it, grind it in the disposal or pour it down the sink, shower or bath, it all reaches the system, and what goes down can have a major effect on how well the system works. Most of the habits that protect a septic system are free.

This guide covers what not to flush with a septic system, what you can put down the drain with a septic tank, and a short checklist for the kitchen and bathroom. It draws on the EPA, university extension services and, for medicines, the Food and Drug Administration.

What not to flush with a septic system: the rule of thumb

The EPA's easy rule is not to flush anything besides human waste and toilet paper. A septic tank is not a trash can. Items that do not break down can fill the tank faster, clog the filter or outlet, or carry through to the drainfield. The University of Georgia Extension makes the same point: things that do not degrade quickly can clog the toilet, tank and system and cause sewage to back up into your home or flood your yard.

The EPA groups the problem items into two types. Cloggers include diapers, cat litter, cigarette filters, coffee grounds, grease and feminine hygiene products. Killers include household chemicals such as gasoline, oil, pesticides, antifreeze and paint, which can harm the living organisms that treat waste.

Do and do-not table

What goes where with a septic system
Item	Toilet or drain?	What the sources say
Human waste and toilet paper	Toilet: yes	The EPA says this is all that should be flushed.
Baby wipes, wet wipes, cleaning wipes	Trash	The EPA lists wipes, including baby and wet wipes, as items not to flush.
Wipes labelled flushable	Trash	See the next section.
Feminine hygiene products, condoms, dental floss, diapers, cigarette butts	Trash	EPA list of items never to flush.
Paper towels, coffee grounds, cat litter	Trash	EPA list of items never to flush.
Cooking grease, oil, fats	Trash, not the drain	The EPA says not to pour grease, oil or fats down the drain. It names butter, wax, cheese and heavy cream.
Medicines	Not the toilet or drain	See the medicines section below.
Gasoline, oil, pesticides, antifreeze, paint, paint thinner	Neither	The EPA says never. Use your local hazardous waste program.
Chemical drain openers	Avoid	The EPA says to avoid them and use boiling water or a drain snake.
Large amounts of toxic cleaners, oil-based paint, solvents	Neither	The EPA says never pour them down the drain, and to minimize even latex paint waste.
Hot tub and pool water	Not into the system	The EPA says emptying a hot tub into a septic system stirs up the solids and can clog the drainfield. Purdue Extension says not to drain chlorine-treated pool or hot tub water into one.

Flushable wipes and septic systems

Packaging may say flushable. The agencies do not accept that for septic systems. The EPA's care guidance lists wipes as items not to flush, and its frequently asked questions page lists non-flushable wipes such as baby wipes or other wet wipes among the things to keep out of the toilet. University of Maryland Extension relays the EPA's advice to flush only toilet paper and put wipes in the trash. The University of Georgia Extension says most sources advise against flushing flushable wipes.

The practical rule is simple. If it is a wipe, put it in the trash. Our guide to clogged drains repeats the point for plumbing generally, since wipes cause trouble on city sewer lines too.

Septic safe toilet paper

Many brands advertise septic safe toilet paper. None of the EPA, extension or state sources we opened set a standard for it, rate brands or define a thickness that counts as septic safe. They say toilet paper is fine to flush and describe what else should stay out. We do not name brands. If you worry about your paper, ask your septic professional what they find at pumping, and keep paper towels and wipes out of the toilet because those belong on the do-not list above.

Garbage disposal and septic

A garbage disposal sends food solids into the tank. The EPA says food waste adds solids that build up as scum and sludge, so a tank that receives disposal waste needs pumping more often. Its guidance is to eliminate or limit disposal use. In a septic home that means:

Scrape plates into the trash or a compost bin first.
Never grind grease, oil, fats, coffee grounds or fibrous scraps.
If you keep the disposal, use it lightly and tell your pumper, so the interval is set for your actual use.

Grease, oil and the kitchen sink

Grease is one of the biggest items in the EPA's cloggers group. In a septic tank, oils and grease float to the top and form scum, and Kansas State University says solids and scum that leave the tank plug the soil pores in the drainfield and slow absorption. Wipe greasy pans with a paper towel, let cooking fat cool, put it in a container and put the container in the trash. Use a sink strainer, as Purdue Extension advises, to keep food particles out.

What can you put down the drain with a septic tank

The sources do not give an approved-products list. What they do say, in plain terms:

Water, and ordinary soap in moderation. Purdue Extension advises using the minimum amount of soap, detergent or bleach needed and mild cleansers only as needed.
Cleaning products in moderation. The EPA's SepticSmart guidance asks owners to use cleaning supplies in moderation and warns that pouring toxins down the drain can kill the organisms that treat waste.
Not automatic toilet bowl blocks. Purdue Extension says the blocks that clip to the bowl or sit in the tank dissolve slowly, releasing bleach and other chemicals into the system over months.
Clogs: boiling water or a snake, not chemicals. The EPA suggests those two. Our guide to clearing a drain yourself notes that boiling water can harm some pipes, so check what yours are made of first, or use hot tap water.

If you wonder whether an additive "treatment" is needed to keep a tank healthy, see septic tank additives and treatments.

Medicines

The EPA says pharmaceuticals should never go down the toilet or drain in a septic home. The Food and Drug Administration says the best option for most unused medicines is a drug take-back location or a mail-back program. Its page on disposing of unused medicines does not mention septic systems. For medicines that are not on its flush list, it describes mixing them with an unappealing substance such as dirt or cat litter, sealing them in a bag and putting them in the household trash, after scratching out personal information on the label.

The FDA also keeps a short list of medicines that it says should be flushed when take-back is not available, because a single dose can be dangerous. If you have a medicine on that list and live on septic, ask your pharmacist or your local health department what to do. Do not guess, and do not flush anything else.

Laundry, water and water softeners

Water volume matters as much as what is in it. The EPA says to spread laundry across the week, because doing it all in one day does not give the tank time to treat waste and can flood the drainfield. Other points from the EPA:

Run full loads or choose the right load size.
Fix leaks. A single leaking toilet can waste up to 200 gallons a day.
High-efficiency toilets, faucet aerators and showerheads reduce what reaches the system.
Some water softeners and purification systems can send hundreds of gallons into the septic tank. Ask a licensed plumber about alternative routing.
Do not drain a hot tub or pool into the system.

Kitchen and bathroom checklist

Kitchen

Scrape plates into the trash or compost before washing.
Wipe greasy pans with a paper towel, then wash.
Pour cooled grease into a container and bin it.
Put a strainer in the sink.
Limit or skip the garbage disposal.
Use cleaning products in small amounts, and never mix products.
Take paint, solvents and automotive fluids to a hazardous waste drop-off.

Bathroom and laundry

Keep a lidded bin next to every toilet for wipes, hygiene products, floss and cotton.
Take medicines to a take-back location instead of the toilet.
Fix a running toilet or dripping faucet this week.
Spread laundry across the week and run full loads.
Skip toilet bowl blocks that release chemicals over time.
Keep a hair catcher in the shower and tub.

If you flushed the wrong thing

One wipe or a bit of floss is unlikely to cause a failure on its own, but repeated habits add up. Stop flushing the item, and if drains are slow, gurgling or backing up, call a licensed septic professional. A backup means avoid contact with the sewage, stop using water and contact your local health department as well. Our guide to signs your septic system is failing helps you judge what you are seeing. Regular inspection and pumping, set out in septic maintenance near me, is what catches buildup early.

What to look up where you live

The EPA does not regulate single-family home systems. States, tribes and local governments do. Your county health department or environmental health office can tell you about local rules and where to take medicines, paint and chemicals. Your state environmental or health agency covers disposal rules. Your state or provincial plumbing or contractor licensing board can confirm a plumber's or septic installer's licence. Rules vary and change, so check the current rules for your area. Note for Canadian readers: provinces regulate onsite wastewater and plumbing, take-back and hazardous waste programs are run locally and costs in Canadian dollars differ, so start with your municipality or regional health unit.

For septic, plumbing and drain company owners

Homeowners search for what not to flush before they search for a company, and a clear page on your own site is how you appear in those searches. See our guides to septic business marketing and the plumber Google Business Profile, or book a free call.

Frequently asked questions

What should you never flush with a septic system?

Never flush anything except human waste and toilet paper. The EPA lists wipes, feminine hygiene products, condoms, dental floss, diapers, cigarette butts, coffee grounds, cat litter, paper towels, grease, medicines and household chemicals such as paint, antifreeze and pesticides as items to keep out.

Are flushable wipes safe for septic systems?

The EPA lists wipes among items not to flush, and extension services say to put them in the trash even when the package says flushable. A package label does not change what a septic tank can handle, so bin all wipes.

Is there such a thing as septic safe toilet paper?

The EPA and extension pages we reviewed say toilet paper may be flushed, but they set no standard or brand list for septic safe toilet paper. Use it in normal amounts, keep paper towels and wipes out of the toilet and ask your septic professional what they see at pumping.

What can you put down the drain with a septic tank?

Water, plus ordinary soap and cleaning products in small amounts. Keep out grease, oil, fats, solvents, paint, large volumes of toxic cleaners and chemical drain openers. For clogs, the EPA suggests boiling water or a drain snake, and Purdue Extension recommends using a sink strainer.

Can I use a garbage disposal with a septic system?

The EPA advises eliminating or limiting it. Food waste adds solids that build up as scum and sludge, so a tank that receives disposal waste needs pumping more often. If you keep one, avoid grease, coffee grounds and fibrous scraps, and tell your pumper.

Can I flush medicines if I have a septic tank?

The EPA says pharmaceuticals should never go down the toilet or drain in a septic home. The FDA says take-back is the best option for most unused medicines and keeps a short flush list for dangerous ones when take-back is unavailable. Ask a pharmacist or your health department if unsure.

Does doing all the laundry in one day hurt a septic system?

It can. The EPA says doing all laundry in one day does not give the tank time to treat waste and can flood the drainfield. Spread loads over the week, run full loads, fix leaking toilets and ask a plumber about routing for water softeners.

What not to flush with a septic system, and what to keep out of the drains