Condensation irrigation (CI) is a combined system for desalination and irrigation. By evaporating seawater in, for example, solar stills and letting the humidified air transport the formed vapour into an underground pipe system, fresh water will precipitate as the air is cooled by the ground. By using drainage pipes for underground air transportation, perforations in the pipes enable the water to percolate into the soil. This study of Cl focuses on the transport of humid air inside buried plain pipes, where the condensed water stays inside the pipe and may thus be collected at the pipe endings and used for drinking. Numerical simulations of this system result in a mean water production capacity of 1.8 kg/m and day over a 50-m long pipe in a diurnally steady system, though shorter pipes result in a higher mean production. A performed theoretical analysis also indicates that Cl is a promising alternative irrigation method as it enables the use of saline water for irrigation.