A waste water drainfield for a sewerage disposal system of the type comprising a plurality of conventional absorption trenches includes a distribution device at each absorption trench for separating waste water into two components of preselected proportions; at least one distribution pipe for each distribution device for temporarily storing a quantity of waste water and/or for distributing the waste water to its respective absorption trench; and distribution lines connecting the distribution devices in series, each distribution device delivering one of the components to its distribution pipes for temporary storage and distribution to its respective absorption trench, and delivering the other of the components to the next distribution device via a distribution line. A method of distributing waste water from a sewerage disposal system to a plurality of conventional absorption trenches comprises the steps of distributing the waste water to the trenches in parallel by delivering the waste water flow to each absorption trench in series, and at each absorption trench separating a preselected proportion of the waste water flow based on the design capacity of that particular absorption trench and the design capacity of the remaining absorption trenches, delivering the preselected proportion of the waste water flow to the trench and delivering the remainder of the flow to the next absorption trench.

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