Working Principle
The sewer system should be designed to ensure cost-effectiveness, aiming for a low and competitive overall cost. The design of the sewer network largely depends on site-specific conditions such as ground profile, pipe size, slope, and depth. Wherever feasible, it is recommended to adopt a gravity-based collection system, as it is more economical and requires minimal operational energy.
Gravity Mains
Gravity mains are a fundamental component of sewerage systems, designed to convey used water through natural gravitational forces. These pipes are laid at a calculated slope to ensure consistent flow towards treatment facilities or pumping stations without the need for mechanical assistance.
Rising Mains
Rising mains, also known as force mains, are pressurized pipelines used to convey used water from pumping stations to higher elevations or directly to the STP. Unlike gravity sewers, rising mains operate under pressure generated by pumps, enabling efficient transport over long distances and varying terrains.
Manholes
Manholes are essential components of the sewer network, providing access for inspection, maintenance, ventilation and cleaning. They are strategically placed along the sewer line to facilitate effective operation and ease of maintenance.
Purpose and Application
Gravity Main
- Transport domestic used water from residential, commercial, and industrial areas to treatment plants or intermediate pumping stations.
- Maintain continuous flow by leveraging gravitational force, thereby minimizing energy consumption.
Rising Main
- Convey used water from low-lying areas to higher elevations.
- Enable flow across uneven terrains where gravity flow is not possible.
- Prevent stagnation and enhance the efficiency of sewer networks.
Manholes
- Provide access for routine inspection, cleaning, and repair of underground sewer lines.
- Allow changes in direction, alignment, gradient, or pipe diameter in the sewer network.
- Enable venting of gases and pressure equalization within the pipeline system to ensure safe and continuous operation.
