The Effectiveness of Native Wetland Plants in Processing Grey Water in an Artificial Wetland System

Grey water is the term given to discharge water from bathtub/showers, sinks, and washing machines.   Approximately 50-80% of household wastewater is grey water and 40-60% of water used by homeowners is directed towards the landscape; therefore, utilizing grey water in the landscape has the potential to conserve water and provide cost savings to the homeowner while providing benefits to the landscape.  However, untreated grey water used on the landscape can raise soil alkalinity and have unknown environmental impact on local and groundwater sources.  When filtered, homeowners could use treated grey water for landscape irrigation with a lowered potential of negative effects.  Artificial wetlands have been shown to successfully remove metals, fecal coliforms, and organic and inorganic chemicals from grey water, but some typical plants used are potentially invasive in some regions of the country. The purpose of this study was to develop an artificial wetland grey water treatment system for Central Texas comprised of local and non-invasive plants to process grey water for landscape use among homeowners.  Plants chosen for the experiment included local and non-invasive plants that tolerate boggy conditions.  These included Typha domingensis Pers. (Cattail), Equisetum hyemale L. (Horsetail), Scirpus americanus Pers. (Bull Rush), Sagittaria platyphylla Engelm. (Arrowhead) and Eleocharis acutangula Roxb. (Texas Rush). Wetland plants were tested on their ability to remove ortho-phosphates (dissolved phosphorus) from grey water. The plants were observed and water samples were tested weekly for ortho-phosphorus, total chlorine, pH, ammonia and nitrates. The results of this pilot study indicated that Horsetail, Bull Rush and Arrowhead are the most promising plants to use in the grey water filtering system in the Central Texas region.