DRAINFIELD DISTRIBUTION SYSTEMS
Parallel drainfleld distribution via distribution box
There is a distribution box between the tank and drainfleld. Effluent flows to all trenches more or less equally. Note how distribution here differs from that above.
Effluent flows from the septic tank into the drainfleld through a system of watertight pipes which ultimately lead to the perforated pipes within the trenches. Various pipe connections maybe included, such as tees, wyes, elbows, distribution boxes, or drop boxes. This is the drainfleld distribution system.
There are two types of distribution systems: parallel and serial. With parallel distribution, effluent flows to all trenches at roughly the same time. With serial distribution, effluent flows initially to the first trench, then to the second, and so on, to each trench in sequence. The disadvantage of the latter system is that the first trench is overworked and often remains saturated, while the remaining trenches receive correspondingly less effluent. This can lead to sequential failure of the trenches. One engineer refers to serial distribution as “designed system failure.”