Septic 101

What Not to Flush in a Septic System

Protecting your septic system starts at the drain. Here’s what to keep out.

Your septic system relies on a delicate bacterial ecosystem to break down waste. Many common household products can kill these essential bacteria, clog your system, or damage components. The simplest way to protect your investment is knowing what should — and shouldn’t — go down your drains.

The Golden Rule

Only three things should enter your septic system: water, human waste, and toilet paper.

Everything else either won’t break down, will kill bacteria, or will accumulate and cause problems. Here’s a detailed breakdown.

Never Flush These Items

“Flushable” Wipes

Despite the marketing, flushable wipes do NOT break down like toilet paper. They accumulate in your tank, wrap around baffles and pumps, and can cause serious clogs. This is the single biggest problem item we see in septic systems today.

Cooking Grease, Oils, and Fats

FOG (fats, oils, grease) solidifies as it cools and forms a thick scum layer in your tank. Excessive grease can overwhelm the tank’s capacity and escape to the drainfield. Pour cooking grease into a container and dispose of it in the trash.

Feminine Hygiene Products

Tampons, pads, and applicators are designed to absorb liquid and expand — exactly the opposite of what you want in a septic tank. They don’t break down and accumulate over time.

Paper Towels and Tissues

Paper towels are designed to be durable when wet — they won’t dissolve in your tank like toilet paper does. The same goes for facial tissues, napkins, and paper plates.

Medications and Pharmaceuticals

Antibiotics and other medications can kill the beneficial bacteria your septic system needs to function. Many drugs also pass through the system and can contaminate groundwater. Dispose of medications at a pharmacy take-back program.

Harsh Chemical Cleaners

Bleach, drain cleaners, antibacterial soaps, and concentrated cleaning products can kill septic bacteria. Small amounts of normal household cleaners are generally okay, but avoid pouring concentrated chemicals or large amounts down the drain.

Cat Litter

Even “flushable” cat litter should never go into a septic system. It doesn’t break down properly, adds unnecessary solids, and cat waste contains parasites that your septic system may not fully eliminate.

Other Items to Keep Out

• Condoms and dental floss
• Cotton swabs and cotton balls
• Diapers (even “biodegradable” ones)
• Hair (use drain screens in showers)
• Paint, solvents, and thinners
• Pesticides and herbicides
• Cigarette butts
• Coffee grounds (compost these instead)
• Food scraps (minimize garbage disposal use)

What About Septic Additives?

Products claiming to eliminate the need for pumping or boost your system’s bacteria are generally unnecessary and can sometimes be harmful. A healthy septic system generates all the bacteria it needs naturally. The best things you can do are: follow these flush/don’t-flush guidelines, conserve water, and stick to a regular pumping and maintenance schedule.

Quick Reference: Flush vs. Don’t Flush