Everyday Use: What Should and Should Not Go Down the Drain
Most premature septic failures come from what goes into the system, not from how it was built.
30 questions in this section
- What is the simple rule for what can be flushed?
- Are flushable wipes safe for septic systems?
- What about tampons, pads and condoms?
- Can I flush dental floss?
- Are paper towels and facial tissues safe?
- Does the type of toilet paper matter?
- Can I flush cat litter, even if it says flushable?
- What about cigarette butts?
- Can I pour cooking grease down the drain?
- What about coffee grounds and eggshells?
- Is bleach bad for a septic system?
- Can I use antibacterial soaps and cleaners?
- Are drain cleaners safe for septic systems?
- What about paint, solvents and thinners?
- Can I flush unused medication?
- Can I use a garbage disposal with a septic system?
- Does a dishwasher hurt a septic system?
- Should I use liquid or powder laundry detergent?
- Are phosphate-free detergents better?
- Can I do laundry all in one day?
- How much water can my system handle at once?
- Does a leaky toilet really matter?
- What about a dripping tap?
- Should I install low-flow fixtures?
- Can I use a hot tub with a septic system?
- What about a swimming pool backwash?
- Can I run a water softener into my septic system?
- What about a whole-house water filter backwash?
- Is it safe to have a floor drain in the basement connected to the septic?
- My house was vacant for months. Is the system still okay?
What is the simple rule for what can be flushed?
Human waste and toilet paper. That is the whole list.
Are flushable wipes safe for septic systems?
No, despite the label. Wipes do not break down quickly, and they collect in the tank and in pipes to form clogs. They are one of the most common causes of pump and baffle failures.
What about tampons, pads and condoms?
None of them should be flushed. They do not decompose, they fill the tank with material the bacteria cannot process, and they can jam pumps and outlet filters.
Can I flush dental floss?
No. Floss does not break down and it tangles into ropes that trap other debris and wrap around pump impellers.
Are paper towels and facial tissues safe?
No. They are designed to hold together when wet, which is the opposite of what toilet paper does. Only toilet paper should be flushed.
Does the type of toilet paper matter?
Somewhat. Thinner, faster-dissolving papers break down more readily. Very thick quilted or plush papers add more solids. Any paper labelled septic-safe that breaks apart quickly in water is fine.
Can I flush cat litter, even if it says flushable?
No. Litter is clay or mineral based and settles into a dense layer that bacteria cannot digest. It also may carry parasites.
What about cigarette butts?
Never. Filters are made of cellulose acetate plastic and do not decompose.
Can I pour cooking grease down the drain?
No. Grease hardens as it cools, coating pipes and building up the scum layer. It also blocks disposal field lines if it makes it that far. Wipe pans and put grease in the garbage.
What about coffee grounds and eggshells?
Both should go in the compost or the garbage. They settle as sludge and are extremely slow to break down.
Is bleach bad for a septic system?
Normal household use for laundry and cleaning is generally tolerated. Large volumes, repeated heavy disinfecting or pouring bleach directly into the tank will kill the bacteria the system depends on.
Can I use antibacterial soaps and cleaners?
Occasional use is fine. Making them your everyday default gradually suppresses the bacterial population in the tank. Milder soaps and cleaners are better for the system.
Are drain cleaners safe for septic systems?
Chemical drain cleaners are harsh on bacteria and on older pipes. For a slow drain, try a drain snake or boiling water first, and call a plumber for persistent blockages.
What about paint, solvents and thinners?
Never. Even small amounts of paints, solvents and thinners can kill the bacteria that break down organic matter in the system. Take them to a household hazardous waste depot.
Can I flush unused medication?
No. Pharmaceuticals pass through the system into groundwater, and antibiotics in quantity can disrupt the tank's bacteria. Take unused medication back to a pharmacy.
Can I use a garbage disposal with a septic system?
You can, but there is a real cost. New Brunswick's Guidelines require a 5 percent increase in daily volume, a 30 percent increase in wastewater strength and a 50 percent increase in sludge storage in the tank. Expect to pump considerably more often.
Does a dishwasher hurt a septic system?
No, provided detergents are used in normal amounts. Run full loads rather than partial ones to reduce total water volume.
Should I use liquid or powder laundry detergent?
Liquid is generally preferable. Some powdered detergents use clay-based fillers that add solids to the tank.
Are phosphate-free detergents better?
Yes. Phosphates pass through the system and contribute to nutrient loading in groundwater and nearby lakes, which matters a great deal in cottage country.
Can I do laundry all in one day?
It is better not to. Several back-to-back loads flood the tank, stir up settled solids and push them toward the field. Spread laundry across the week.
How much water can my system handle at once?
Your system is designed for a daily volume, not a burst. Even a well-designed system suffers if a whole day's flow arrives in two hours. Stagger showers, dishwashing and laundry.
Does a leaky toilet really matter?
Enormously. A silently running toilet can add hundreds of litres a day, which is a large fraction of a home's design flow. It is one of the most common hidden causes of septic overload.
What about a dripping tap?
Less dramatic than a toilet but still worth fixing. Steady water entering the system does no treatment work and shortens the effective life of the field.
Should I install low-flow fixtures?
They are good for your system and your well. Just be aware that in New Brunswick, water-saving fixtures do not permit a smaller system to be designed, because reduced water use increases wastewater strength.
Can I use a hot tub with a septic system?
Do not drain a hot tub into the septic system. The volume alone can flood the field, and the chlorine or bromine will harm the bacteria. Drain it well away from the disposal field, onto a vegetated area.
What about a swimming pool backwash?
Same answer. Never route pool water or filter backwash into the septic system. Also remember that a future pool affects lot layout and should be planned for when the system is designed.
Can I run a water softener into my septic system?
In New Brunswick it can be permitted, but the design must add 15 percent to the peak daily wastewater volume. Discuss it with your installer rather than adding one after the fact.
What about a whole-house water filter backwash?
Backwash from water treatment devices is generally excluded from the design flow unless specifically approved. Check with Technical Inspection Services before connecting one.
Is it safe to have a floor drain in the basement connected to the septic?
A floor drain that only receives incidental water may be acceptable, but the Guidelines count a floor drain as 190 litres per unit of design flow. A floor drain that receives groundwater or sump discharge must not be connected.
My house was vacant for months. Is the system still okay?
Probably, but the bacterial population declines during long vacancies. Resume normal use gradually, avoid dumping a huge volume of water at once, and have the system inspected if it was empty for a full season.
Have a question about your own property? General answers only go so far — your soil, slope, water table and setbacks are specific to your lot. Call (506) 233-6272 or send us the details.
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