This standard provides guidelines for the siting, design, construction, operation, and maintenance of onsite domestic wastewater treatment systems. It focuses on septic tanks for primary treatment and soil absorption systems (like soak pits and dispersion trenches) for secondary treatment and disposal.
Provides comprehensive guidelines for the design, construction, operation, and maintenance of onsite wastewater treatment and disposal systems, including septic tanks and soil absorption systems.
Quick Reference Values
Minimum septic tank liquid capacity2000 Litres
Minimum freeboard in septic tank300 mm
Minimum distance from a drinking water well15 m
Typical desludging period2 to 3 years
Minimum depth of water seal for traps75 mm
Minimum width of dispersion trench0.3 m
Key Formulas
Absorption Area (A) = Effluent flow (Q) / Application Rate (Ra)
Practical Notes
The percolation test (Clause 6.2) is the most critical step for designing a functional soil absorption system; improper execution is a common cause of system failure.
Strictly adhere to the minimum separation distances in Table 1 to prevent contamination of drinking water sources and damage to building foundations.
Regular desludging (every 2-3 years) is essential for the long-term performance of the septic system and to prevent solids from clogging the absorption field.