Known water supply systems are fed from a source of water such as a tank (6) via a pump (5) to outlets which are occludable by means of a cock (C1-C3). A water pressure sensitive electrical switch (S1) is located downstream of the pump (5) and upstream of the outlets. The switch (S1) is connected in series with an electrical supply for the pump and turns the pump on in response in a drop in water pressure downstream of the switch. Similarly the pump is turned off in response to water pressure downstream to the switch reaching a predetermined minimum pressure, A control system is disclosed in the form of a timer (T) connected in parallel with the pump (5) and energized via the switch (S1). A normally closed safeguard switch (S2) is connected in series with the pump and rendered non-conductive by the timer (T) being energized for a predetermined period. The safeguard switch (S2) prevents the pump (5) operating continuously for more than a predetermine period, typically 15-30 minutes, As a consequence leaks in the system supplied by the pump (5) do not result in excessive water loss from the tank (6), A system and method to prevent water loss in a reticulated town water supply system is also disclosed by means of a flow detector (FD), a timer (T) and a normally open solenoid valve (SV).