Prepared by Mohammad al-Asad and Majd Musa in association with Richard Brittain, 2002
In 1983, the City of Tucson carried out a road-widening project in suburban Tucson, and subsequently bought the houses located along this particular road with the intention of demolishing them. Brittain and his colleagues convinced the city authorities that one of the residential properties had the potential of being modified and retrofitted as a demonstration and research site for water conservation practices. The single-family residence was very close to a shopping mall, which meant that many people would go to that area, and the mall visitors could be attracted to visit the house through effective advertising. The house was given the name "Casa del Agua," which is Spanish for "House of Water." It was opened for visitors in September 1985, and operated as a demonstration house until April 1999, when it became Tucson Water's conservation offices.
Casa del Agua (figure 1) is a typical ranch-style house that had lawn all around it and was landscaped with the high-water-use plants typical of the Tucson area. Also, it conformed to the customary practice in Tucson of diverting all the rainwater that falls on a residential property off the site and into the street where it would end up in the municipal storm sewer system. The project team worked on developing Casa del Agua in order to accommodate water conservation and data collection purposes. The design development was implemented through several modifications to the original structure and the landscaping of the plot on which it is located. Consequently, the project team removed the lawn and vegetation in the front yard, except for the large African sumac (Rhus lancea) tree that provided the western side of the house with highly needed shade. Several years later this tree was blown over in a monsoon storm and was replaced with a mesquite. They created a concave front yard area with a berm around its perimeter to retain rainwater on-site rather than have it end up on the street. The team also built a ramada across the front yard with vines planted next to it to provide additional shade. Moreover, they reconfigured the driveway so that it would slope towards the concave front yard and direct the rainwater into the site.
Alterations were also applied to the backyard (figure 2). Most of the lawn area was removed and brick paving was installed with a slope that directed rainwater to a very small lawn area surrounding a tree. Low-water-use plants were installed and irrigated through a drip irrigation system. (4) A passive solar greenhouse was built on the south side of the house. This was used to grow certain food crops, and also to provide the house with passive solar heating in the wintertime.
The project incorporated a rainwater harvesting system. (5) The project team increased the harvested rainwater catchment area of the project by increasing the roof area, which now occupied 232 square meters. Storm water was conveyed to underground storage tanks by means of rain gutters and downspouts. Prior to entering the tanks, storm water flowed through a filter box, where a simple window screen was used as a filtration device that would stop the leaves and other debris from making their way into the storage tanks.
Inside the house, the concrete floor of the master bathroom was cut open to reach the drainage pipes located underneath the slab. A new set of pipes was installed to allow for the separation of graywater from blackwater. Graywater, which includes sink, bathtub, shower, and washing machine water, was made to flow into a recycling system. Blackwater, which includes toilet and kitchen sink water, was directed to the municipal sewer system. Here, Brittain mentioned that the project team members decided to route the wastewater from the kitchen sink into the municipal sewer system because of the degradable material it contains from food waste and food scraps. Such materials make the wastewater from the sink hazardous and unsuitable for use without additional treatment.