Indirect Potable Reuse Water
By Saumya Garg
(This is Part 3 of a three-part series on Reclaimed Water. Part 1 of the series was an introduction on reused water. In Part 2 we looked at Direct Potable Reuse of water.)
Indirect Potable Reuse (IPR) water is when reclaimed water is released to environmental buffers such as reservoirs and aquifers to be treated and used later for drinking water. IPR is preferred when there is a readily available environmental buffer that is good quality and cost efficient to maintain, protect, operate and monitor.
There are currently 14 IPR projects that are operational in the USA. Of these, the largest facility is the Orange County Groundwater Replenishment System (GWRS) Advanced Water Treatment Facility which reclaims 100 million gallons of water every day (MGD). The facility was set up in 2008 and later expanded in 2015. The $624 million plant is the world’s largest and uses a three-step process (microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide) to produce reclaimed water. Part of this reclaimed water is then pumped into injection wells to act as a sea water intrusion barrier and the remaining is pumped to recharge groundwater basins in Anaheim. The GWRS is currently undergoing a $310 million final expansion to increase capacity by an additional 30 MGD of water.
Another large IPR project that is currently under study is the Hampton Roads Sanitation District’s SWIFT project in Virginia. Once developed, the plants are expected to reclaim 120 MGD of water and inject it into the Potomac Aquifer for groundwater replenishment to alleviate salt water intrusion and subsidence in the Tidewater area from Virginia Beach to Chesapeake as well as Newport News – Yorktown.
Although no federal regulations specifically address indirect potable water reuse, IPR facilities are well regulated by state provided regulations and guidelines. As of 2017, fourteen states (Arizona, California, Florida, Hawaii, Idaho, Massachusetts, Nevada, North Carolina, Oklahoma, Oregon, Pennsylvania, Texas, Virginia, Washington) have clear policies surrounding Indirect Potable Reuse of water.
As mentioned earlier in this series on reclaimed water, there is a significant cost attached to reusing water for potable purposes. However, irrespective of the type of reuse (direct or indirect) and setup & operational costs involved, utilizing reclaimed water itself is extremely cost efficient in the long run. For example, the Orange County GWRS cost $481 million to setup initially. Since its inception, the plant has produced over 155 billion gallons of reclaimed water, which would have otherwise cost $318 million to import from Northern California or the Colorado River. Further, the plant produces a water supply at nearly half the power required to pump water from Northern California – energy equivalent to powering 30,000 homes every year.
Reuse water is slowly gaining popularity globally. The advances in water treatment technologies have made it increasingly easy to implement Potable Reuse facilities. As the hurdles of cost and public perception give way, more states will begin to realize the true value of reclaimed water.
Many wastewater facilities in Florida are injecting their treated effluent into aquifers for storage and future recovery after the water percolates and blends into the existing groundwater supplies in the Sunshine state. In Florida they have many years of success using treated effluent for irrigation and farming in the city and the country. When you are vacationing there, you can see the famous purple pipe everywhere that there is reuse water going through their reclaimed water distribution pipes.