What Not to Put in Your Septic System (Texas Guide)

Only toilet paper and human waste belong in your septic tank. Grease, wipes, chemicals, and medications kill bacteria and cause $5,000-$20,000 in drain field damage.

Most septic failures in Texas aren't caused by old equipment. They're caused by what homeowners put down the drain. Per the EPA's Septic System Owner's Guide, your tank relies on billions of bacteria to break down waste. Kill those bacteria or overwhelm them with things they can't digest, and you're looking at backups, drain field failure, and repair bills that start at $1,000 and climb fast.

This guide covers the obvious items plus Texas-specific concerns that most lists skip: water softener brine (a real issue with Texas well water), garbage disposal impact on systems built in clay soil, and pool water rules.

Problem Item	Why It's Harmful	Risk Level	Potential Repair Cost
Grease, oils, fats	Coats drain field soil permanently	High	$5,000-$20,000
"Flushable" wipes	Won't break down, clogs pumps	High	$250-$1,000+
Household chemicals	Kills essential bacteria	High	$250-$500 (re-treatment)
Medications/antibiotics	Wipes out bacterial colonies for weeks	High	$250-$500
Garbage disposal overuse	Doubles solid waste, fills tank faster	Moderate	$1,500-$2,000 extra pumping over 20 years
Pool/hot tub water	Volume floods tank, chlorine kills bacteria	High	$5,000-$15,000
Water softener (old unit)	Excess brine disrupts settling	Low-Moderate	$250-$400 (extra pumping)

What Items Should Never Go in a Septic System?

Wipes, grease, chemicals, and medications top the banned list. These items either resist breakdown or kill the bacteria your tank needs to function.

Print this out. Stick it on your fridge or under the kitchen sink. These are the items that cause the most septic problems in Texas homes.

Never flush:

• "Flushable" wipes (they don't break down, no matter what the label says)
• Feminine hygiene products (tampons, pads)
• Diapers
• Cotton swabs, cotton balls, dental floss
• Condoms, bandages
• Cat litter (even "flushable" brands)
• Paper towels or tissues (they're thicker than toilet paper and don't dissolve)
• Cigarette butts
• Hair

Never pour down drains:

• Cooking oil, grease, butter, bacon fat
• Paint, paint thinner, solvents
• Gasoline, motor oil, antifreeze
• Bleach in large amounts (a small amount in laundry is fine; pouring a bottle down the drain is not)
• Drain cleaner (especially caustic/chemical types)
• Medications and antibiotics
• Pesticides, herbicides, fertilizer

Use with caution:

• Antibacterial soap (biodegradable alternatives are better for septic)
• Fabric softener (liquid softeners add chemicals; dryer sheets are a better option)
• Harsh cleaning products (switch to septic-safe or natural cleaners)

Why Is Grease the Worst Thing for a Septic System?

Fats, oils, and grease (FOG) are the number one cause of preventable septic problems because they float, coat surfaces, and resist bacterial breakdown.

Grease doesn't just clog your pipes. It floats to the top of your septic tank and forms a thick scum layer. That layer blocks the natural process where bacteria break down waste. As Anish R. Jantrania, Associate Professor and Extension Specialist at Texas A&M AgriLife Extension, warns in the agency's septic maintenance guide: "If sludge or scum accumulates to those points, solids will leave the tank with the liquid and can clog or plug the soil in the drainfield." Over time, grease also escapes into the drain field, coating the soil particles that are supposed to filter your wastewater. Once grease clogs your drain field soil, the damage is often permanent.

The fix is simple. Scrape plates into the trash. Pour cooking oil into a container and throw it away. Wipe greasy pans with a paper towel before washing. These small habits prevent the most expensive septic repair: drain field replacement, which costs $5,000-$20,000 in Texas according to HomeGuide and local contractor estimates.

How Does a Garbage Disposal Affect Your Septic?

Garbage disposals roughly double the solid waste entering your tank, cutting pumping intervals from every 3-5 years to every 2-3 years.

Texas A&M's OSSF program specifically warns against excessive garbage disposal use with septic systems. Here's why: your tank's bacteria are designed to digest human waste, not ground-up food scraps. Food particles are bulkier, take longer to decompose, and many (like vegetable peels, eggshells, and coffee grounds) barely break down at all.

Septic technicians in Texas frequently find a visible pile of food waste under the inlet pipe when pumping tanks in homes with heavy garbage disposal use. That material takes up tank capacity and forces partially treated water into the drain field sooner than it should.

If you have a garbage disposal and a septic system:

• Use it sparingly, not as a food waste processor
• Never grind fibrous vegetables (celery, corn husks, onion skins)
• Avoid putting coffee grounds or eggshells through it
• Expect to pump more often (budget for every 2-3 years instead of 3-5)
• Consider composting food scraps instead

The cost difference is real. Pumping every 2.5 years instead of every 4 years adds roughly $1,500-$2,000 in extra pumping costs over 20 years.

Can Water Softener Brine Hurt Your Septic System?

High-efficiency water softeners don't harm septic systems or drain fields, but inefficient units producing excess brine can disrupt settling and increase tank maintenance.

Texas has some of the hardest well water in the country, especially in the Hill Country and Edwards Plateau regions. Hardness levels of 15-25 grains per gallon are common. That pushes a lot of homeowners toward water softeners, which raises the question: is the salty brine safe for your septic?

The research is more nuanced than most websites suggest.

A National Sanitation Foundation (NSF) study found that brine from efficient softeners causes no harm to septic bacteria, even at double the normal discharge rate. University of Wisconsin research confirmed this and noted that the calcium and magnesium in softener discharge can actually help solids settle in the tank. A 2013 Water Quality Research Foundation study at Virginia Tech found similar results.

The catch is efficiency. Modern demand-initiated softeners that regenerate based on actual water use (using 3,000-4,000 grains of hardness per pound of salt) produce minimal brine. Older timer-based units that regenerate on a fixed schedule, regardless of usage, waste salt and water. Those inefficient units produce excess sodium that can hurt solids settling in the tank.

If you have hard Texas well water and a septic system:

• Use a high-efficiency, demand-initiated softener (not a timer-based model)
• Potassium chloride works as well as sodium chloride, with comparable septic impact
• Consider a separate brine disposal line (drywell) if your softener is older
• Don't skip the softener entirely, because hard water scale damages your plumbing, appliances, and water heater

Can You Drain Pool or Hot Tub Water into a Septic System?

Never drain pool or hot tub water into your septic system. The volume overwhelms the tank, and chlorine kills the bacteria your system needs.

A typical hot tub holds 300-500 gallons. A pool holds 10,000-20,000 gallons or more. Dumping that volume into a septic system floods the tank, pushes untreated water into the drain field, and the chlorine or bromine in treated water wipes out the bacterial colony.

Drain pool and hot tub water onto landscaping (away from the septic area), into a storm drain where permitted, or through a dedicated drainage line. Check your local county rules. Some Texas municipalities have specific requirements about where treated pool water can be discharged.

Backwash from pool filters is a different problem. It contains concentrated chemicals plus captured debris. That goes in the trash or a dedicated waste line, never into the septic system.

When Should You Call a Septic Professional?

Schedule a pump-and-inspect visit if you've regularly flushed prohibited items. Catching problems early costs $250-$500 vs. $5,000-$20,000 for drain field replacement.

If you've been putting any of the items above into your system regularly, don't panic, but do get your tank pumped and inspected. A professional can check sludge and scum levels, look for early signs of drain field trouble, and tell you if your current habits have caused damage.

If you're seeing signs your septic system is failing like slow drains, odors, or wet spots in the yard, get an inspection sooner rather than later. Catching problems early saves thousands.

Need your septic system inspected? Find licensed Texas providers in your area

Frequently Asked Questions

Can you use bleach with a septic system?

Small amounts of bleach in normal laundry use won't harm your septic system. The dilution from a typical wash load is enough that the bacteria recover quickly. Pouring straight bleach or large amounts of bleach-based cleaner down a drain can disrupt the bacterial balance for days or weeks. Use septic-safe cleaners when possible.

Are "flushable" wipes safe for septic systems?

No. "Flushable" wipes do not break down like toilet paper and are one of the most common causes of septic clogs and pump failures. They pass through the toilet fine, but they accumulate in the tank and wrap around pumps in aerobic systems. Use them if you want, but put them in the trash, not the toilet.

Does a garbage disposal hurt a septic system?

It doesn't destroy it, but it makes the system work harder. Garbage disposals roughly double the solid waste entering your tank, meaning you'll need to pump more often (every 2-3 years instead of 3-5). Texas A&M recommends against excessive garbage disposal use with septic systems. If you use one, keep it light and avoid fibrous foods.

Is water softener salt bad for septic tanks?

Not with a modern high-efficiency softener. NSF and university studies show that efficient softeners (3,000+ grains per pound of salt) don't harm septic bacteria or drain fields. Older, inefficient timer-based units can cause problems by producing too much brine. If you have hard Texas well water, a properly sized demand-initiated softener is the safest option.

Can I pour old medications down the drain with a septic system?

No. Medications, especially antibiotics, kill the bacteria your septic system needs to function. Antibiotics can wipe out bacterial populations for weeks. Take unused medications to a pharmacy take-back program or a DEA National Prescription Drug Take-Back location. Many Texas pharmacies and police departments accept old medications.

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Last updated: February 8, 2026 Reviewed by: Texas Septic Guide Editorial Team, content verified against TCEQ guidance, Texas A&M OSSF recommendations, and NSF/WQRF research Sources: Texas A&M AgriLife Extension OSSF program (ossf.tamu.edu), NSF water softener/septic studies, Water Quality Research Foundation / Virginia Tech (2013), TCEQ OSSF guidance, EPA Septic System Owner's Guide