A battery operated self-contained submersible liquid dispenser for dispensing discrete quantities of a liquid from a remote liquid reservoir is provided. The dispenser comprises a hermetically sealed walled housing containing a peristaltic pump driven either directly or via a speed reduction gear train by an electric motor in response to motor activation signals received from an electric control circuit within the housing. The pump includes a flexible liquid dispensing tube connected to respective liquid inlet and liquid outlet ports extending through the wall of the housing, a pump actuator for forcing liquid received via the liquid inlet port through the tube to the outlet port, and a sensor on or in the wall of the housing connected to the circuit. The sensor is adapted to sense a changed condition from a required parameter external to the housing, e.g., such as the presence or absence of water, the circuit thereafter activating the motor and hence the pump to dispense a discrete quantity of the liquid