To construct sewer systems certain rules and regulations have to be followed based on quality of pipes chosen, alignment and so on. Pipeline networks are designed by engineers based on city and installed by sewer contractors.

Open drains often carry storm water. In rainy seasons water level increases in drains. If it contains clogging or any operations to be done, it becomes difficult if depth is more.

The velocity of 3 ft/sec is considered to be minimum to keep foreign particles moving in sewers. The Washington State Department of Health (DOH) recommends a maximum velocity of 8 ft/sec but permits greater velocities during fire flow conditions.

The high rate of flow of water can lead to increasing sound levels of flow which leads to noise. Hence minimum flow of water should be considered. 0.5-0.7 m/s is maximum velocity of tap water that produces less noise levels. 1.0-2.5 m/s of water flow leads to high noise levels.

One of sewer wastewater treatment processes is a biological treatment known as activated-sludge process. Wastewater is agitated and aerated to remove solids and oxidation methods are introduced to activate decomposition.

Storm water does not act as a distinctive factor for installation of sewer systems. The type of sewer installed depends upon terrain, where it is placed and uses. Sanitary sewers are most common type of system used to transport wastewater and industrial waste.

In separate systems, two sets of sewers are used to carry sanitary sewage and storm/ surface water separately. In combined system, a single sewer with a larger size is used to carry both sanitary sewage and surface water toger.

Trench sewer construction is most common pipeline installation method. At grade level, sewers can be installed and protected by an embankment or a wall, or placed inside tunnel walls.

The legal entity that is responsible for wastewater collection system is Wastewater Collection System Agency. It is also called Sewer System Agency.

In dry wear flow stormwater is less or absent. During wet wear flow, quantity of stormwater increases. As in partial systems, a part of stormwater is direct to sanitary sewers, stormwater puts a load on treatment plants by increasing quantity of water to be treated.