Abstract: A self-contained device for sterilizing water is provided comprising a sterilizing product injection apparatus supplied with power by electric batteries so as to cause injection of the sterilizing product into a pipe transporting water to be treated, a water meter mounted in said pipe and having a head capable of generating a pulse each time the meter has recorded the flow of a predetermined amount of water, and an electric power regulator controlled by said pulses and which, whenever it receives a pulse, lets the current from the battery pass in the form of a short duration signal, the regulator interrupting the current from the battery between the pulses emitted by the meter.