A drinker system for delivering water to animals comprising: a central pressure regulator drinker lines with drinker nozzles pressure reduction valve devices providing an outlet pressure proportional to the pressure set by the central pressure regulator each valve device comprising: a housing defining a relatively high pressure zone and a relatively low pressure zone a relatively small area diaphragm in the relatively high pressure zone a relatively large area diaphragm in the relatively low pressure zone, and rigidly connected to the small area diaphragm a flow regulating valve through which liquid can flow from the relatively high pressure zone to the relatively low pressure zone and an internal by-pass mechanism for allowing liquid to flow from the valve device inlet to the valve device outlet bypassing the flow regulating valve.
