That better arrangement is illustrated in. With this setup the effluent is now distributed more uniformly through the absorption field. Instead of a single septic tank, two tanks are used by the Plumbers. The tank connected to the house sewer is referred to as a septic tank or sometimes as a settling tank. This tank is connected to another called the siphon tank which is filter less.
Like the basic septic tank, the settling tank has a submerged outlet, and, as a matter of fact, the settling tank works in the same way as the basic tank using pipes. As the liquid effluent in the settling tank rises, it will discharge through the submerged outlet when its level is high enough. The effluent then flows into the siphon tank instead of directly into drain tiles.
Note that the siphon tank is equipped with a trap,sometimes made of iron. The higher the level of liquid in the tank, the more corn- pressed the air,usually the gas leaking is poisonous and settles over the liquid, infact in the region above the liquid. The effluent will continue to rise, however, until it reaches the level indicated as “high water line” in the drawing. By now the air above the effluent is highly compressed and exerts enough pressure on the surface of the liquid to force the liquid through the trap,at times it may seem as if boilers have been used.
The action is just as though you had flushed a toilet. There is now a rapid flow of effluent through the drain tiles to the drainage field, but because the effluent flows with considerable velocity, it reaches all parts of the field. The pressure of the air above the effluent exerts a force similar to that of a pump, but once the flow of water has started through the trap, the continuing action is like that of a siphon. In other words, air pressure starts the movement of effluent through the trap, and siphon age continues it.
Note the cap placed above the drain pipe leading to the trap . The flow of effluent will continue until the level of effluent reaches the edge of the cap, and then it will stop. No further effluent will go out to the drainage field, and once again the siphon tank will start filling until it reaches the high water line,even if water from a heater is used.
Drain Tile Capacity
The total volume of the drain tiles, or its capacity, is often made equal to the volume of one complete discharge. This means that during a single discharge from the siphon tank, the drain tile system is completely filled, and so the effluent escapes into all parts of the absorption field. The absorption field is thus used to its maximum capability. There is little chance of backup into the siphon tank, even though some effluent may be coming into it from the septic tank. Actually, there may be a long time before the siphon tank discharges again. During this period, oxygen in the air penetrates the earth or the filtration bed. The effluent is given an opportunity to evaporate,laundry water and all.
The siphon tank is equipped with a vent. The purpose of this vent, unlike that of the venting systems used inside the home, is to permit the escape of liquid effluent if the siphon should become clogged.
A siphon system can be added to an existing septic tank installation. There are various types of siphon systems. Whether you need a siphon tank depends on the extent to which fixtures in the home are used. When a home is used for year- round living and has a number of occupants, a siphon tank might be necessary; weekend or summer homes, it might not.
There are other factors to consider. The house might be situated on a high level and so the drain tiles could have a pitch or slope that would ensure good distribution of the effluent to all parts of the absorption field, something not possible where the ground is flat. Or the drain tiles might discharge into an already polluted stream or into salt water. In some cases, two or three septic tanks are used, with one discharging into another. All these septic tanks are of the same size and construction,once you make a video or a cd of it there wont be any problems.
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