What’s the best way to keep our septic from clogging?

What is the best way to keep our septic system from clogging up? I’ve heard about products that prevent organic build-ups or promise to keep my septic system running forever. But should I simply be vigilant about what goes into it?
—Gerrie Storr, via email

The basic rule is: Flush only human waste and toilet paper (ideally, paper that breaks down easily, since TP contributes to much of the bulk that builds up in the tank). Conversely, avoid flushing or dumping basically anything else, in particular, stuff that won’t decompose quickly (diapers, tampons, cooking fat and grease, cigarette butts) or is toxic (paints, solvents, gas, old medication, pesticides). Take it easy with the antibacterial detergents when you’re washing dishes and, when cleaning or doing laundry, only use bleach if necessary. Strong cleaning products can interfere with the important bacteria in the septic tank.

Other tips? Since excessive water use overloads the system, conserve, conserve, conserve! Use a low-flow toilet, don’t run your dishwasher unnecessarily, and spread out your loads of laundry, instead of doing all the washing on one day. And, of course, make sure you get regular tank pump-outs: Most systems need this once every three to five years (but it varies). Don’t wait until things start to stink…by then it may already be too late.

If you diligently follow every rule of good septic system ownership, will yours last forever? Probably not. But that doesn’t mean you should use septic additives. Many experts believe they’re not helpful. Sure, there are products that ramp up bacterial growth in the tank, but adding more sewage to the system does this anyway. (For free.) Also, some additives—for example, products that claim to unclog pipes—would be dangerous if they got into the water supply.

If you’re going to use an additive, reject anything with lye, formaldehyde, quaternary ammonium, colour, fragrance, or a hazard symbol, and look for a product that contains bacteria that can break down the cellulose in toilet paper.