For gravity main systems, in ...

For gravity main systems, in my area, Greece - Halkidiki county, keeping the pipes and manholes clean seems to always work, e.g. by performing scheduled washings (1 wash per month or per period of returning odors) with the use of pressurized water. However, this method transfers huge amounts of biological plus inertial solids downstream, so it should be followed by simultaneous solids removal from the system. The same method is advised when odors emitted from house sewage holes. It is old but good and efficient.