Unfortunately,years ago many properties were connected to these shared supplies,i had lots of trouble when working for the water board in the 1980s.
In the early 1900s all the houses would have had was a sink in the "kitchen"with one cold tap,and an outside bog.The one water pipe shared between 6 or so terraced houses,was sufficient,legislation was virtually non existant.
Many of these shared supplies still exist,and cause problems with low pressure/flow now that properties have indoor bathrooms,second loo,washing machines,and dishwashers,and people often only realise they are connected to one,when a leak occurs,or someone turns the water off,not realising they are also shutting off 5 others.