Other sewerage facilities besides combined and separated are simplified sewers, solid free sewers, pressurised sewers, vacuum sewers and open channel drains which are shortly described below.

Simplified sewers are sewer systems that are constructed using smaller diameter pipes laid at a shallower depth and at a flatter gradient than combined sewers. They allow a more flexible design associated with lower costs and a higher number of connected households. The costs of simplified sewerage systems are between 50 to 80% lower than conventional combined sewers.

Solid free sewers are similar to conventional combined sewer systems, except that the wastewater is pre-settled and solids are removed before entering the system. As solids are removed the sewer diameter can be much smaller and due to the simplified design solids-free sewers can be built cheaper. But the pre-settling units must be maintained and emptied regularly to ensure optimal performance.

Pressurised sewers are an effective solutions where conventional systems are impractical such as in rocky, hilly or densely populated areas or areas with a high groundwater table. A pit containing a grinder and pump or a settling unit (septic tank) connected to a holding tank with a pump are installed close to the user. When a certain level of effluent has been collected, it is pumped into the sewer, generating the pressure for transportation. The capital costs are higher than with simplified and solid free sewers, but still lower than with onventional combined sewers. But all system components need frequent maintenance and should be regularly serviced.

Vacuum sewer systems use a central vacuum source to convey sewage from individual households to a central collection station. When the collection tank at the end of the vacuum system fills to a predetermined level, sewage pumps transfer the contents to a treatment plant via a conventional or separate sewer system. These high-tech systems are costly but cheaper than conventional sewer system. The systems needs instructed workers for maintenance and operation works can save big amounts of flushing water.They are suitable in areas where a collection is needed but other options are too costly or not feasible, where rock layers or a high groundwater table make deep excavation difficult and areas which are short of water supply.

Open channel drains are conveyances in which water flows with a free surface. Although closed conduits such as culverts and storm drains are open channels when flowing partially full, the term is generally applied to natural and improved watercourses, gutters, ditches and channels. Open channls are less expensive compared to underground sewer systems and can be constructed in almost all types of settlements (urban or rural) but enough land area is required to build a reasonable construction. Even though they offer simple solutions for stormwater drainage, they bear many risks for public health and the environment due to the risk of illegal discharge of wastewater and solid waste.

(Seyoum 2013)