In cities with problems of aridity and a shortage of drinking water supply, there is an urgent need to establish alternatives for an adequate water management program. This study proposes an estimation through which users can select a rainwater harvesting system for non-drinking water consumption. For the cities of Pachuca and Mineral de la Reforma, State of Hidalgo, Central Mexico, the historical record of rainfall analyzed covers a period of 33 years (1980–2013). We calculated the monthly volume of rainwater harvestable from roof areas (VR, m³) with household roof areas (Hra) of 45 m², 50 m², 100 m² and 200 m². It is proposed to replace in each single house the flush toilets and washing machine with ecological devices with consumptions of 4.8 L/flush and 70 L/load, respectively. Furthermore, a maximum and a minimum consumption of eight and six flushes/day/person (flush toilets) and five and four loads/week (washing machine), respectively, are proposed. From these considerations, our estimations of the harvestable rainwater showed that households with Hra of 45 m² and 50 m² would depend on the water supply system of the public network during part of the year. On the other hand, households with Hra of 100 m² and 200 m² might be able to store enough water to meet other needs besides toilet flushing and laundry.

En este trabajo se analizaron las posibilidades de implementar tecnologías de bajo impacto (cosecha de agua de lluvia en azoteas y pavimento permeable) en viviendas de tipo unifamiliar. Se cuantificaron los volúmenes de agua de lluvia cosechables y se di señó una mezcla de pavimento permeable para determinar sus propiedades mecánicas (resistencia a la compresión) e hidráulicas (permeabilidad). Se observó que es posible cosechar volúmenes suficientes de agua en azoteas de viviendas unifamiliares con superficies de 100 m2 que satisfagan al menos el 25% del volumen necesario para fines no potables. Además, es posible facilitar la infiltración de escorrentía superficial a través de pavimentos permeables destinados a estacionamientos, cocheras y andadores. Este tipo de tecnologías podrían auto-construirse por usuarios y propietarios.