Bali traditional septic tank

his traditional sewage system was in many case well done, with large volume, inspection cover.

Clarified water was dispersed underground.

In the past centuries the system was adequate to the village life.

But in the 21 century it's not adequate.

We use more and more water, many chemicals are used in house hold and THE POPULATION INCREASE !

To better understand the real problem the standard bacteria reduction rate of a well maintained septic tank is about 50 % !

Traditional septic tank problems

The correct definition of septic tank used in Bali is dispersion or rubble pit.

Your "tukan" is buiding it with "Batako " bricks and very few cement.

The main problems are:

• Outlet water is not digested so bacteria and polluting substances are not digested and reduced.
• Pollution is concentrated in a single point, so the natural pollution removal of the ground is overloaded.
• In crowed areas or small garden extension this means polluted your well and your garden with very dangerous healt's risks.
• In "not adsorbing ground" you are going to create a "swimming pool" of waste water
• Modern laundry and kitchen soaps reacts with the kitchen oils and grease to "film" the ground and reduce the water passage. After some time you can have waste water flood in your yard.

Some times a second chamber is installed and filled with small rocks and or Syrap.

If the first digestion chamber is water tight this can be an effective biofilter.

Unfortunately design do not allow back wash and maintenance and the modern soaps may block it developing hard rocks

Here contractor put sand and gravel outside the Batako septic tank. In few months grease ans soap clog it and create septic tank flooding.

Sources and Types of Bacteria and Protozoa in Domestic Waste water

The main source of bacteria and protozoa in wastewater is human feces. Other minor sources include sputum, vomitus, contaminated clothing that goes through a washing machine, and normal skin flora that enters bath or shower water (U.S. EPA 2011). The U.S. EPA (2011) reports that within just one gram of human feces there are one trillion bacteria of various types. There are too many types of bacteria present in wastewater to enumerate. Thus, in most cases, indicator bacteria such as fecal coliforms and fecal streptococci are measured in wastewater because the task of detecting all possible microorganisms is complex and cost-prohibitive. The use of indicator bacteria is based on the assumption that fecal bacteria in the wastewater are survivors of the intestinal flora and that the presence of fecal coliforms and fecal streptococci can be used to reflect the possible presence of all human pathogens in wastewater.

tables from :Soil and Water Science Department, Florida Cooperative Extension Service, Institute of Food and

Agricultural Sciences, University of Florida.