Abstract: The invention relates to a method for producing a pure mixture comprising fuel, water and an emulsifier for a combustion device. According to the method, a mixture pump located in a fuel circuit ensures that a volume of the fuel mixture used by the combustion device is constantly replaced with an identical volume of fuel, water and emulsifier. The quantity of water and emulsifier added to the mixture and consequently, the mix ratio of the components in the fuel mixture, is metered according to the fuel volume flow of fuel that is drawn from the fuel tank by the mixture pump, as metered by a metering device. The method guarantees for less operation and does not necessitate any intervention in existing control systems for the combustion device. A device for carrying out the method can be constructed simply by fitting an add-on device into an existing fuel circuit.