Monthly Archives: June 2015

California’s Drought and Direct Potable Reuse (DPR)

Updated on January 3, 2017

This post on water reuse below was the most popular blog post of 2015, and was the most popular blog post again of 2016 – no doubt as the issue of water scarcity has become more and more acute.

Since this article was first posted, we have developed a whole site just on the topic of water reuse and UV disinfection. Check out the website here.

Water Reuse and UV


Drought and Potable Reuse in California

Originally posted June 25, 2015

As California’s historic drought lingers on, cities and towns are looking for any source of water they can find, including what some call “toilet to tap.” We prefer to call it potable reuse, and it can either indirectly (i.e. indirect potable reuse or IPR) or directly (i.e. direct potable reuse or DPR) add to drinking water supplies.

The reuse of wastewater for augmentation of drinking water supplies continues to gain widespread support, and is being adopted as a means of achieving a sustainable water supply in the face of drought.

Indirect Potable Reuse

Some contaminants – such as nitrosamines (e.g., NDMA), pharmaceuticals, and industrial solvents – are not fully removed by microfiltration and reverse osmosis. These chemical contaminants must be removed before the water can safely be reused, and that’s why many IPR and DPR facilities install UV at the end of their treatment train.

Trojan Technologies has provided UV systems to numerous advanced water treatment facilities globally that are proactively addressing critical water shortages.

These include:

  • Orange County Water District’s Groundwater Replenishment (GWRS) System in California, see the case study
  • Groundwater Recovery Enhancement and Treatment (GREAT) Program in Oxnard, California
  • Direct Potable Water Reuse with UV-Oxidation – Big Spring, Texas, see the case study

CBS Coverage on California’s ‘Toilet to Tap’ Programs

CBS News Coverage
The TrojanUVPhox™ is the UV system in place at the Orange County Water District plant as the third step in the treatment process following microfiltration and reverse osmosis. The plant provides enough water for nearly 850,000 people per year and is “the cleanest water in the State of California.”

CBS 60 Minutes Feature – Depleting the Water
Correspondent, Lesley Stahl, reports on California’s 4th straight year in a drought and the causes and implications of its diminishing groundwater supplies in this excellent 60 Minutes feature “Depleting the Water“. She visits the Orange County Water District plant where she tastes the water treated by the TrojanUVPhox™, stating that “it wasn’t bad.”

Lesley Stahl of 60 Minutes at Orange County Water District

Lesley Stahl taste tests the water at Orange County Water District’s Groundwater Replenishment System. TrojanUVPhox systems are featured prominently behind her.

Further Reading