Septic Tank Primer

Let’s begin with the history of the flush toilet, which made its debut about 1600 in Britain, culminating in the brilliant design of Alexander Cumming in 1775 (and not Mr Crapper, who invented the ball cock), which internalized the “S” trap and left some water in the bowl to avoid, shall we say, sticky things sticking to the side of the bowl. So fine was his design that it has remained virtually unchanged for over 150 years. This was a wonderful advance over the chamber pot – for the user. However, in the cities, the waste water simply flowed into the street gutter, mixing nicely with the horse manure and other garbage for the poor street sweeper to remove at night. In the country, toilet water flowed into a pit (the cesspool), which was similarly cleaned by staff.

It took almost a century for a lucky Frenchman in 1860 to put a top on the pit and enclose it. After a year, he opened it and was surprised (and likely delighted) to find that there was only a surface scum and some liquid in the pit. Thus was born the septic tank. What the Frenchman had accidentally discovered was that when toilet wastes are kept away from air, the anaerobic bacteria, which are residing in your very own gut at this moment, transform the poo solids into a sanitary liquid.

This is exactly the same process that I used when building biodigesters in Peru. Only we used animal manure from pigs, goats and cows. The bacteria very quickly convert solid to liquid and give off methane (natural gas), which we used as a cooking fuel. The resulting liquid, which has very little odor, is free from any pathogens, as they are killed off by the lack of oxygen. It makes an outstanding liquid fertilizer that can be applied and absorbed directly by plant foliage. In theory, you could use the effluent liquid from your septic tank for fertilizer. But the Code Inspector would throw a fit. As usual, I digress.

This septic tank system worked flawlessly for many years. If only toilet waste “Black water” goes into the tank, it will run in near perpetuity, without any pump out or other maintenance. And you don’t need a large tank. A family of 4 would need only about a 200 gal tank. But then, (I’m not sure when) some bright builder decided it would be a grand idea to put ALL the household water waste into the tank. And all Hell broke loose. You see, the anaerobic bacteria can digest urine and poo just fine, but they can’t digest soaps, oils, fats, grease, hair, fingernails, coffee grounds, paper towels, sanitary napkins, tampons, diapers, hand wipes, motor oil, cleaning solvents, bleach, lubricants, gasoline, paints, thinners, or pesticides. (Food waste is fine, except for bones, but why not compost them instead?) So, all those “other” items build up in the tank and eventually, you need to call the “Honey Wagon” for a pump out removal of all those materials.

Even worse, most of those products above are toxic to the bacteria. Kill those bacteria and the poo no longer liquefies, further compounding the tank accumulations.

The solution is to simply to go back to the beginning - separate the black water from the grey water and run the grey water directly to the leach field or through a separate digester to break down soaps and oils.. Not so hard in new construction, but retro-fitting an existing home would be a nightmare, unless you live in a raised floor home. The other issue is that most unenlightened municipal building codes will not allow this kind of plumbing. Not because it’s bad, just because it’s not in the code book.

So, what’s a body to do if they are stuck with the standard septic tank system? Pump outs are all but unavoidable, eventually. But, you can lengthen the time between Honey Wagon visits by simply not putting ANY of the aforementioned items down the drain. Or, at least, as little and as few as possible. Also, limiting the amount of water that goes down the drain will help. That means no half hour showers or leaving the tap running or flushing down a single tissue after you blow your nose. All good water conservation strategies, as well.

There are a plethora of septic tank additives on the market, all claiming to keep your tank healthy, if you’ll just use them on a regular basis. To my mind, they are just snake oil. You can’t introduce anaerobic bacteria from a packet. Besides you naturally supply a new batch of free bacteria every time you poop. Better just follow the guidelines above and save some money for your next pump out.

Toilet paper addendum:
One of the things that the septic bacteria can't digest is cellulose. Unfortunately, that is just what TP is made of. Thus, the purist would not put it down the drain. Use of a bidet or the classic 3rd World option of a trash bin for used TP would be in order.
For the non-purist, there is (sort of) good news : it's OK to wipe and drop. While the TP will not be digested, it will dissolve into tiny fibers, which will eventually be discharged to the drain field and acted upon by another group of bacteria.
Advertisers will try and sell you their "special" TP for septic tanks at a very special price. Don't fall for this and waste your money. The truth is that any single ply TP (and especially the cheapest brands) will dissolve in the tank.
Here's the simple test : take a sheet of TP and put it in a glass of water. Stir "with great vigor" ala JFK. The faster the TP dissolves, the better it is for your septic system. Cheaper brands are usually the best, in this case.
Still, you want to minimize TP use and NEVER use "wipes" which are much more durable.