A fluid dispensing device that dispenses a fluid into a stream of water or any other substance. The dispensing device comprises a conduit with an inlet and an outlet, the inlet being configured to receive the fluid and the outlet being configured to dispense it. The dispensing device also comprises a piston and a spring connected to each other and disposed within the conduit, the spring displacing the piston. 

Purpose: To inject a specific amount of disinfectant fluid into the water entering a cistern. In our particular case, it’s used to inject a liquid substance into the water flow entering the toilet tank, in order to eliminate viruses and bacteria present in the wastewater from the toilet flush.