On-Site Direct Potable Reuse: A New Approach to Improving Groundwater Sustainability
Tuesday, December 5, 2017: 1:20 p.m.
In many regions of the United States, and elsewhere, groundwater supplies are rapidly diminishing due to overuse or becoming increasingly contaminated. Groundwater is the conventional source for potable water in millions of houses and businesses without connections to centralized water systems. On-site direct potable reuse (DPR) is a new approach to reduce withdrawal of groundwater from aquifers via private wells and release of partially treated wastewater into the subsurface via septic systems. Specifically, the water that has been used by a home or small business is recycled to yield purified water that is safe for all indoor uses rather than being discharged to the septic system as a waste product. In addition to maintaining a potable water supply, on-site DPR could preserve and protect aquifers by reducing groundwater withdrawals that are not necessarily replenished by infiltration of septic system effluent, and by reducing subsurface release of pathogens, nutrients, and other contaminants.
New legislation passed in Ohio in 2014 added ‘recycled water’ as a source for private water systems serving fewer than 15 service connections or 25 people on average. An on-site DPR pilot study was run from 2013 through 2016, and the system is now indefinitely approved as a potable water source for the office building that it serves. Following an initial testing period with purified water discharged to the septic system, the water has been plumbed into the building since 2014 and approved for all indoor uses including drinking and cooking since 2015. Extensive testing overseen by regulators and reviewed by an international panel of water experts demonstrated the excellent quality of the purified water and reliability of the advanced water treatment process. To date, this on-site DPR system has reduced dependence upon the well and volumetric loading to the septic system by upwards of 1.5 million liters.