Permeable pavements for water recycling and reuse: initial results and future prospects

Pervious pavements (meaning permeable pavements within this context and used interchangeably) may be used as storage devices for grey water in order to reduce the demand for mains water. Water collected from roofs may be stored beneath pavements and used for lowgrade domestic uses such as landscaping and possibly toilet flushing. As demand for this water may exceed supply during summer months or in regions with a dry climate, evaporative losses of stored water are significant to the provision of a secure supply. In a series of pilot experiments conducted under controlled conditions, water was stored in a variety of model pavement systems, with and without a geotextile and with different types of geotextile. It was discovered that a geotextile comprising two layers, one permeable but able to attenuate contaminants, and the other providing a barrier to water vapour was significantly better at
reducing evaporation than either no geotextile or an oil attenuating geotextile alone. Where a similar experiment was conducted in a field setting, the two-layered geotextile performed best at preventing evaporation, but the water level was constantly recharged by rainfall, and this allowed water to persist in all of the tested systems. It is hoped to model these results in the context of a theoretical demand for stored water to determine just how much storage may be needed. It is also important to determine the infiltration rates and water quality
implications of using the new geotextile.