The effect of septic tanks on ground water characteristics

Abstract EN

In the early and mid decades of the previous century, the lack of a simple and economic option for the offsite conveyance and treatment of domestic sewage in Egyptian rural areas lead to the sole dependence on septic tanks for the onsite disposal of domestic sewage.

As time went on the unpredicted demographic reshaping that had undergone in all Egyptian rural areas coupled with the un-engineered guidance in the construction of almost all the septic tanks has lead to a failing system of septic tanks.

Currently almost all Egyptian rural areas are already facing environmental degradation.

This is a result of the overload on the existing onsite septic tanks that resulted in frequent streets overflow, potential health hazards, high ground water level, contamination of ground waters, rivers and streams together with a long list of service management deficiencies.

In this study a survey was conducted on existing septic tanks.

Ground water samples were collected from around septic tanks to a diameter of 40 meters.

The effect of the septic tanks was monitored during three operational conditions.

The first condition when the tank in its ordinary operational sequence.

The second when the tank fully emptied and the third when the tank connected to a small bore sewer system.

The second operational condition gave the best results as the surrounding water seeped back into the tank.

The third operational condition showed that by connecting the septic tanks to small bore sewers the pollution area of the septic tank dropped by about 50 %.

The first operational condition was the worst case.

The study achieved its aim by indicating that the pollution effects of septic tanks can be reduced by connecting it to a small bore sewer system or by rehabilitating it or by both because it is virtually illogic to demolish the thousands of septic tanks currently existing and operating in Egyptian rural areas for new watertight tanks.

Thus by reducing the pollution effects of septic tanks, all the rural populations in Egypt will benefit.