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and filled with each use, to stop the back-flow of bad smells, and there are also pipe vents sticking up out of the roof.
A lot of activity goes on in a septic tank, with good bacteria eliminating bad bacteria, converting solids into liquid. As the liquid level rises, it leaves the tank by a pipe, with floating solids blocked by baffles.
The exit pipe carries the effluent into a series of downward sloping underground tubes, usually perforated plastic tubing up to 100-feet long, spread out in a graveled-surrounded drainfield at least 18 inches underground. ■
The liquid then moves upward by capillary action, providing nutrients to vegetation, with much moisture evaporating into the air.
The wastewater also percolates downward, where oxygen and bacteria in the soil cleanse the wastewater as it passes through two-three feet of soil.
90.8%