A liquid charging and discharge cycle control mechanism in the form of a cistern water wastage control mechanism 10 comprises a displaceably mounted flow control member in the form of a conventional cistern water supply regulation piston 12 forming part of a piston and cylinder assembly 16, buoyancy providing means as provided by a buoyancy sphere 18 that interacts ball cock fashion with the piston 12 and a releasable locking device in the form of a spring biased finger-like formation 22 that is releasably engageable with an element receiving location in the form of a bore 24 into the piston 12. Except when a cistern fitted with the mechanism is triggered to perform a flushing action the formation 22 locks the mechanism 10 against a continuous upstream refilling action in the case of cistern leakage.
