Feature Article May 29, 2002
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After John Crapper - Part Oneby Gray MerriamSeptic systems used to be just an outhouse. Many of us grew up with them. Then John Crapper invented the flush toilet, and its outlet often went out into a pit called a cesspool. There were fewer of us then, and we were careful around places that smelled like outhouses. Smelly seepage around cesspools and close-by neighbours soon produced a better system a tank with a pipe out near the top flowing to a tile field. The tile field was just a network of clay tile laid on a bed of gravel. The idea was that bacteria and yeasts in the tank (septic refers to germs -- these micro-organisms) would digest or break down some of the solids in the tank. The rest of the solids would sink and the liquid would slowly flow off the top into the pipe to the tile field. There the liquid, filled with dissolved nutrients from the waste, and with bacteria from the human digestive tract, would soak through the clay tile and gravel into the soil. Nutrients and bacteria would be filtered out by the soil, if there was enough and the soil was the right type. Liquid soaking upwards into the soil over the gravel would be absorbed by the roots of plants growing on the tile bed. The plants would build the nutrients into their tissue and pump the water out through their leaves where it could evaporate into the air. Quite a neat system when it was working correctly.
Although septic systems are living machines where the bacteria and yeasts in the tank and the grass on the tile bed do the work, they need some maintenance by us to continue working correctly. If we put too much liquid into the system at one time it may flood the tile bed (when too many weekend visitors take too many showers and wash too many clothes). The plant roots cant take it up fast enough and it flows away through the soil, over the rocks and into the lake. If you are on limestone, it moves down into the flow channels in the rock and into neighbouring wells. If we dont pump the septic tank regularly, the solids will fill the tank right up to the outflow pipe, and both liquid and undigested solids will flow out into the tile bed. This not only will flood the tile bed, but also will clog the tile with the solids flowing from the over-full tank. In our northern areas, on the granitic rock, too little soil can cause liquid from the tile bed to flow over the rock and into the water with little or no filtering. Hence, the high-tech clays imported for some tile beds and the peat moss filtration and the pumped, multi-tank, filtered systems being installed today.
Even well-built septic systems can malfunction if not well-maintained. Many septic systems throughout our landscape were built before the development of modern septic systems. Some are very old. Some were built without full understanding of how septic systems are supposed to work. Many were itll-do-for-now designs. Neighbours were not close by and there were few on the lake.
Times have changed. Homes and cottages are dense enough now that the danger from intestinal viruses and bacteria from one dwelling can be a health hazard for neighbours. And if even a small fraction of all the septic systems ringing a lake or strung along a river should malfunction, they can cause enough nutrients to flow into the lake or river to lower water quality. The process of over-feeding a lake with nutrients is now called eutrophication; over-feeding can change everything that lives in the lake. It can cause too much plant growth, including algae, and when the plants die, too much oxygen from the water is used to decompose them. As a result, fish can die for lack of oxygen. This over-feeding of lakes is a very common, major effect of over-development of shorelines with homes and cottages. Poorly working septic systems are a major cause of this effect. Many lake associations are monitoring this effect in their lakes with Secchi disk readings and phosphorus measurements. Stopping this change in water quality depends on all of our septic systems working properly, whether new or old. It also depends on good planning of lake development by municipal councils and taxpayers.
This article is the first in a series on septic systems and the importance of maintaining them properly.
