Wastewater disposal systems are considered to be one of the most basic and important elements in a city’s development and progress, especially as technological progress is still imposing additional requirements in this field, resulting in the designers having to consider more than just economic and conventional factors. Wastewater disposal systems are based on a sewer system, a lateral sewer is one that serves one or a small number of streets; a sub-main sewer collects sewage from two or more lateral sewers and discharges it into a main sewer. The main then discharges into a trunk. From the trunk, the wastewater is sent to the wastewater treatment plant. As the economic factor is considered to be an important aspect in the design of a separate sewer system, a great deal of emphasis has been given to developing a system in this research that is suitable in terms of the environment, economy and hydraulics. This innovative system for the sewer networks will include a proposed new design for the pipe shape that will allow the storm flow and the sewage flow to pass through the same pipe, which has two sections, without mixing. This will have the advantages of providing a combined sewer system and a separate sewer system in one system, and will comply with the 21st-century requirements (sustainability, protection of public health, and reduced cost), as one trench will be used for one pipe with two sections (storm section and sanitary section).