and maintenance of the sewer lines is not necessary manholes are not required Usually only a single vacuum pump station is required rather than multiple stations found in gravity and low pressure networks. This frees up land, reduces energy costs and reduces operational costs. investment costs can be reduced up to 50% due to simple trenching at shallow depths, close to surface flexibile piping allows obstacles to be over- or underpassed reduced installation time small diameter sewer pipes of HDPE, PVC materials; savings of material costs aeration of sewage, less development of H2S, with its dangers for workers, inhabitants, as well as corrosion of the pipes may be avoided; sewage is kept fresh no odours along the closed vacuum sewers no stormwater infiltration, therefore less hydraulic load at the wastewater treatment plant no sewage leakages (vacuum avoids exfiltration), which is not only an ecological/public health benefit, but also makes repairs to the pipes easier and more sanitary for repair workers sewers may be laid in the same trench with other mains, also with potable water or storm-water, as well as in water protection areas Lower cost to maintain in the long term due to shallow trenching and easy identification of problems In combination of vacuum toilets it creates concentrated waste streams, which makes it feasible to use different waste water treatment techniques, like anaerobic treatment Disadvantages vacuum systems are not capable of transporting sewage over very long distances, but can pump long distances from the vacuum station to the next sewage treatment plant or main gravity sewer. vacuum sewerage systems are only capable of the collection of wastewater within a separated system (not for the collection of storm water) the lines can only reach up to 3–4 km laid in flat area (restrictions of the system due to headlosses (3-4.5 m) (friction and static)) systems should be designed with help of an experienced manufacturer (concepts are usually free of charge) external energy is required at the central vacuum station; an emergency power supply, such as a backup generator, is needed for power outages. odours close to the vacuum station can occur, a biofilter may be necessary integrity of the pipe joints is paramount grease can clog the sensor tube (if set up incorrectly) thus requiring preventative maintenance cleaning vacuum valves can get stuck open leading to pressure drops in the entire system. However, a monitoring system can help identifying stuck