Barcombe Mills is a small settlement and an area of countryside including a local nature reserve near the village of Barcombe Cross in East Sussex, England. It is located in the civil parish of Barcombe in the Lewes District. It is an important area for its wildlife, natural environment and water storage. The River Ouse and Andrew's Stream, one of its tributaries and popular for fishing, flow through the area and Barcombe Reservoir is adjacent. The area includes a small hamlet and some farms, including Barcombe House, and a water treatment works.