Drains/sewers usually rely on gravity, i.e. the pipes are laid to a fall (slope), allowing the effluent to flow away. However should a building (or buildings) be below the level of an existing sewer then a pumping station is required to pump the effluent back up to the level of the gravity sewer, where it then flows away under gravity. The Fens are naturally flat, hence Anglian Water rely heavily on pumping water from place to place! There are also a number of large pumping stations in that area purely to drain the Fens back into the river!
Pumps of this type are nearly always of the 'submersible' type, where the pump is designed to remain underwater. Will be fitted with 'float switches', high float switches the pump on when water level reaches set level, lower float senses level has dropped, and switches pump off again. In normal operation should be virtually, if not completely silent. Should any noise be noted then it should be investigated, could be a sign pump is not switching off as required. Running the pump 'dry', out of water will cause it to rapidly fail!
Will be a control cabinet nearby (usually green!) which houses the electrical apparatus, and often fitted with an orange warning beacon on top to alert of pump failure/high water level in the tank. Pumps should be of heavy duty type to handle effluent but still need treating with some respect. Wipes, sanitary products, fat/oil/grease, basically anything that hasn't been through you first
should not be put down the drains. These will clog/jam the pump(s) also causing premature failure. Should pump failure occur then you may need to arrange for the system to be pumped out with a tanker (Local Council may offer such a service), pending pump replacement. A thorough clean may be advisable prior to any new pump being fitted if there are undesirable items in the system, or premature failure of the new pump may occur.
If it is pumping to a septic tank as opposed to mains drainage then that's another can of worms......
