An aircraft comprising an engine, an inlet and an environmental control system coupled to the engine configured to provide high-pressure high-temperature bleed air, the environmental control system being coupled to the inlet configured to provide fresh air, the environmental control system comprising: an outflow heat exchanger configured to cool the high-pressure high-temperature bleed air to produce cold high-pressure bleed air; a primary heat exchanger; a secondary heat exchanger a compressing device comprising a compressor and a turbine; wherein the turbine produces in use a mixed air; and a moisture removal circuit comprising a high-pressure water separator and middle-pressure water separator, wherein the high-pressure water separator comprises a first condenser and a first water extractor, wherein the middle-pressure water separator comprises a second condenser and a second water extractor; wherein the primary heat exchanger is configured to cool the cold high-pressure bleed air to nearly ambient temperature to produce ambient high-pressure bleed air, wherein the first condenser utilizes in use the mixed air as a heat sink to cool the ambient high-pressure bleed air which enters the first condenser, where it is cooled to produce high-pressure low-temperature bleed air, wherein the high-pressure low-temperature bleed air flows in use through the first water extractor, wherein moisture is removed to produce dry high-pressure bleed air which enters the turbine, and wherein the compressor compresses in use the fresh air to produce a medium-pressure fresh air; wherein the secondary heat exchanger is configured to cool the medium-pressure fresh air to nearly ambient temperature to produce cool medium-pressure fresh air; wherein, when the environmental control system is operating in a first mode, the cool medium-pressure fresh air is directed by a valve to the second condenser; wherein the second condenser utilizes in use the mixed air as a heat sink to cool the cool medium-pressure fresh air which enters the second condenser, where it is cooled to produce cold medium-pressure fresh air; wherein the cold medium-pressure fresh air flows in use through the second water extractor, where moisture is removed to produce cold dry medium-pressure fresh air which enters the turbine; and wherein the cold dry medium-pressure fresh air and the dry high-pressure bleed air are mixed in use at the turbine to produce mixed air an outflow heat exchanger configured to cool the high-pressure high-temperature bleed air to produce cold high-pressure bleed air; a primary heat exchanger; a secondary heat exchanger a compressing device comprising a compressor and a turbine; wherein the turbine produces in use a mixed air; and a moisture removal circuit comprising a high-pressure water separator and middle-pressure water separator, wherein the high-pressure water separator comprises a first condenser and a first water extractor, wherein the middle-pressure water separator comprises a second condenser and a second water extractor; wherein the primary heat exchanger is configured to cool the cold high-pressure bleed air to nearly ambient temperature to produce ambient high-pressure bleed air, wherein the first condenser utilizes in use the mixed air as a heat sink to cool the ambient high-pressure bleed air which enters the first condenser, where it is cooled to produce high-pressure low-temperature bleed air, wherein the high-pressure low-temperature bleed air flows in use through the first water extractor, wherein moisture is removed to produce dry high-pressure bleed air which enters the turbine, and wherein the compressor compresses in use the fresh air to produce a medium-pressure fresh air; wherein the secondary heat exchanger is configured to cool the medium-pressure fresh air to nearly ambient temperature to produce cool medium-pressure fresh air; wherein, when the environmental control system is operating in a first mode, the cool medium-pressure fresh air is directed by a valve to the second condenser; wherein the second condenser utilizes in use the mixed air as a heat sink to cool the cool medium-pressure fresh air which enters the second condenser, where it is cooled to produce cold medium-pressure fresh air; wherein the cold medium-pressure fresh air flows in use through the second water extractor, where moisture is removed to produce cold dry medium-pressure fresh air which enters the turbine; and wherein the cold dry medium-pressure fresh air and the dry high-pressure bleed air are mixed in use at the turbine to produce mixed air