A method for producing a treated water stream, the method comprising the steps of: receiving a feed stream comprising at least one substance mixed in a water phase; and processing the feed water stream in a plurality of stages arranged in operation from a lowest temperature and pressure to a highest temperature and pressure, to produce the treated water stream and a concentrated stream, wherein each stage comprises a vessel (170,171,172), a heat exchanger (140,141,143), an evaporator, and a condenser, feeding the feed water stream into a first stage operated at the lowest temperature and pressure compared to the other stages, an evaporator of the first stage being configured to produce a water vapor stream that is condensed by a condenser physically arranged outside of the vessel of the first stage to produce a first treated water stream, extracting a brine-concentrate from the evaporator of the first stage and feeding the brine-concentrated feed stream to an evaporator of a second stage, the second stage comprising a higher temperature and pressure than the first stage, to produce an additional treated water stream and a successive brine-concentrated stream that is fed to an evaporator of a successive stage for the plurality of stages, each successive stage comprising a higher temperature and pressure than a preceding stage, an evaporator of each successive stage being configured to produce an additional treated water stream and a successive brine-concentrated stream that is fed to an evaporator of a successive stage for the plurality of stages, and extracting brine from the brine-concentrated stream from an evaporator of a stage having the highest temperature and pressure compared to the other stages, the extracted brine being used to provide energy to heat the brine-concentrated stream (109, 106) being fed to each of the evaporators of the plurality of stages, wherein the heat exchanger (140,141,143) at each stage is an external heat exchanger that receives energy from an available external heat energy to evaporate water and generate steam in the vessel, wherein each evaporator is configured to evaporate an amount of water using indirect heat, and wherein each condenser is configured to condense at least a portion of steam generated by a successive stage. receiving a feed stream comprising at least one substance mixed in a water phase; and processing the feed water stream in a plurality of stages arranged in operation from a lowest temperature and pressure to a highest temperature and pressure, to produce the treated water stream and a concentrated stream, wherein each stage comprises a vessel (170,171,172), a heat exchanger (140,141,143), an evaporator, and a condenser, feeding the feed water stream into a first stage operated at the lowest temperature and pressure compared to the other stages, an evaporator of the first stage being configured to produce a water vapor stream that is condensed by a condenser physically arranged outside of the vessel of the first stage to produce a first treated water stream, extracting a brine-concentrate from the evaporator of the first stage and feeding the brine-concentrated feed stream to an evaporator of a second stage, the second stage comprising a higher temperature and pressure than the first stage, to produce an additional treated water stream and a successive brine-concentrated stream that is fed to an evaporator of a successive stage for the plurality of stages, each successive stage comprising a higher temperature and pressure than a preceding stage, an evaporator of each successive stage being configured to produce an additional treated water stream and a successive brine-concentrated stream that is fed to an evaporator of a successive stage for the plurality of stages, and extracting brine from the brine-concentrated stream from an evaporator of a stage having the highest temperature and pressure compared to the other stages, the extracted brine being used to provide energy to heat the brine-concentrated stream (109, 106) being fed to each of the evaporators of the plurality of stages, wherein the heat exchanger (140,141,143) at each stage is an external heat exchanger that receives energy from an available external heat energy to evaporate water and generate steam in the vessel, wherein each evaporator is configured to evaporate an amount of water using indirect heat, and wherein each condenser is configured to condense at least a portion of steam generated by a successive stage.