The land applications are appropriate systems for the purification of domestic wastewaters, of small rural populations. Their efficiency is high and if their management is suitable, they can provide an economic benefit that could help to their maintenance. It is indispensable to carry out studies of the physical environment during the design phase of these systems for their correct location. In 'the case of the land application of Patones, these studies were not carried out and the consequences were tlie elimination of land that should act like purification filter