|a typical septic arrangement|
The "suck-truck" operator was very knowledgeable on the subject and gave us a few tips. He said that the tank should be sucked out about every 3 years or so to remove the accumulated solids, this depends on the size of the tank and the number of people using it. If the solids build up to the top of the tank and start to be transported into the evaporation trench it will eventually block up and you will have to dig up the whole thing and start again. Not to mention the potential for pathogens to accumulate near the surface of the trench.
He also told us not to use any chlorine. This will just kill the microbes that are working to break down the sludge and it will have to by pumped out more often. Some toilet cleaning products claim to be "septic safe" while still containing chlorine, so he recommended to use natural cleaning products (bicarb soda and vinegar) instead. Just another reason to ditch the chemicals! The only bleach we use is in cleaning the beer fermenters, so that is now being tipped outside instead of down the drain.
So if you have a septic system that hasn't been pumped out for a while, its probably worth getting a suck-truck out to do the job, then at least you know you're not going to block up your trench and have expensive repair work instead! The other advantage for us is that most of our grey water goes to the garden instead of filling up the septic tank.
Do you have a septic tank? Any tips for maintaining it?