What kills a septic tank, and what does it no harm
The list of things to avoid is everywhere, and it is often wrong. Here is what really causes problems, and what goes through without any trouble.
A septic tank is not a storage tank, it is a digester: bacteria break down the waste inside it. So the right question is not ‘is it chemical?’ but ‘does it kill the bacteria, or does it clog?’
What kills the bacteria
Too much bleach
It disinfects, which means it kills. A splash is fine, a litre a week sterilises the tank.
Corrosive drain unblockers
Poured down the sink, they reach the tank barely diluted and do there what they do to the blockage.
Solvents and medicines
White spirit, acetone, leftover paint, antibiotics. None of these belongs in a drain.
What clogs without killing anything
Wipes
Even ‘biodegradable’ ones. They break down in an industrial treatment plant, not in a septic tank. The number one cause of blockages.
Cooking fats
They set as they cool and form a crust that cuts the tank off from the air.
Anything that cannot be digested
Sanitary products, cotton wool, hair, cat litter, large amounts of coffee grounds.
What causes no problem at all
- Laundry detergent and fabric softener, at normal doses.
- Vinegar, baking soda, washing soda, in normal household use.
- Soap, shampoo, toothpaste.
- Toilet paper, which is exactly what the tank is designed to digest.
Drain unblockers and descalers
It all comes down to the formula. Biological unblockers, with enzymes or bacteria, strengthen the tank instead of disrupting it. Drain unblockers made with naturally derived caustic soda are suitable for septic tank connections under normal conditions of use, as their technical sheet states. A standard caustic unblocker from the shop does not say so, and for good reason.
The same goes for the toilet bowl: a conventional descaler disrupts the balance downstream. A descaler designed for septic tanks descales and adds bacteria at the same time.
If the damage is done
A maintenance dose will not be enough. Odours, backing up, slow drainage: use the Septic tank emergency treatment or the Septic tank unblocker, then resume weekly maintenance one week later, and fix whatever caused the problem in the first place.
The doses for our products are on their packaging, and that is what counts. If swallowed or splashed, call the Poison Centre on +32 70 245 245 and keep the packaging to hand.
