Household Effluent Treatment

BEND OF ISLANDS CONSERVATION ASSOCIATION

Treatment of Household Effluent

Definition

By effluent we mean sewerage and sullage (waste fluids from kitchen and laundry) and the current practice is for both to be collected in a standard septic tank with its overflow treated in an appropriate manner. Always use bio-degradable soaps and detergents so that the tank will operate.

Septic tanks

Traditional septic tanks are cast concrete and come in two sizes, large and small depending on the household size. For steep or inaccessible sites the much lighter and easy to manoeuvre fibreglass tanks may be used. Tanks may need to be de-sludged every seven years so allow access for this purpose. However they must be airtight for the bacteria to operate. They can need re-starting or rejuvenating with bacteriological input.

Toilets

Ensure toilets are as close as possible to the septic tank so that good sewerage flow results and that the septic tank does not need to become very deep in the ground to maintain an adequate slope for piping which enters it. Specify dual flush cisterns to conserve water and investigate the various designs as some have superior noise and flow characteristics. Note: Other toilet designs are available which utilise electrical, gas or biological disposal systems so that no sewerage requiring treatment in a tank is generated - thus a septic tank would not be necessary. Many such systems require energy input - this is an environmental factor to consider.

Post septic tank

Traditionally the outflow from here is conveyed along a certain length of piped trench for release by soaking into the soil. Perforated plastic pipe is very popular, lying in a bed of aggregate or scoria and used for longer runs. For shorter runs Reln drain may be used. This however tends to concentrate the dispersal to a smaller area. In obviously sensitive areas a sand trap may be specified and this will enable less trenching to be used. There are alternatives involving terracing or transpiration beds. With terracing the natural seepage from the high point of the slope could be used to provide moisture and nutrient to successive terraces along the distribution length. Alternatively the outflow from the septic tank can be piped or pumped to a transpiration bed. This is a plastic lined area of some 40 square metres with a subterranean distribution system of aggregate and reln drain covered by 300 to 500 mm of suitable soil. Reln drain can also be used in a linear configuration. It needs a wider trench than traditional agricultural pipe but a much shorter run. Garden bed can be established over it in the manner of a transpiration bed. Both these approaches enable vegetables and small trees to be grown in a specified area with regular water and nutrient supply. \

What You Need to Do

Nilllumbik Shire are the regulating authority and they should be consulted for any issues involving waste treatment and disposal on your property. As a rule, septic tanks and the associated works (e.g., drainage lines) should be inspected on a regular basis. Septic tanks should be pumped out by a contractor about every five years.