A liquid pressure tank is provided for storing liquid under pressure for use in domestic or commercial reticulated supply of the type having an impervious bladder dividing the tank into an air chamber and a liquid chamber, a constant amount of air being maintained in the chamber under pressure. A liquid pump and pressure switch system is provided for maintaining liquid in the chamber between preset pressure limits, and the tank includes a liquid outlet control comprising a seat member and a resilient disc member mounted in spaced relation from the seat and arranged to be deformed around the seat when contacted by the bladder mounted therearound to at least partially close the outlet and prevent rupturing of the bladder when liquid is substantially exhausted from the tank.