With the increasing focus throughout California on storm water capture and reuse, urged on by our current historic drought, we are all familiar with the many benefits that arise from responsible management of storm water. These benefits can include increased water supply reliability, improved water quality throughout a watershed, decreased flood risks, and the protection and improvement of wildlife habitats and green space. The list goes on!
Illustration of route of human exposure to storm water pollutants during different storm water use (Jiang Y et al, 2015).
Alta Environmental has been participating in discussions with local jurisdictions regarding the development of regulations and guidelines for managing the risk of Legionella and other human pathogens in storm water treatment, reuse, or recycling. The typical exposure pathway for Legionella has not historically been a concern for storm water; however, storm water BMPs and new uses that aerosolize captured storm water may harbor biofilm development and could potentially pose a risk for Legionella exposure. These BMPs and reuse activities include, but are not limited to:
There are existing standards and guidelines that address the risk of Legionella in building water systems, including ANSI/ASHRAE Standard 188-2015 “Legionellosis: Risk Management for Building Water Systems” (Standard 188). Compliance with the Standard involves analyzing building water systems to determine if a project contains factors or devices that relate to legionellosis and certain storm water BMPs could potentially represent such a device.
At Alta, we believe that storm water treatment, reuse, or recycling may have similar potential health risks from Legionella exposure as the potable water systems addressed in this standard. It is vitally important to consider the potential risks along with the benefits as we grow our use of storm water for non-potable activities. Other health concerns, like vector control and the breeding of mosquitos, must be considered in addition to the possible exposure to human pathogens. Guidance specifically for storm water BMP implementation and management is needed to ensure protection of human health from Legionella and other possible human health risks in storm water reuse. Because storm water is such a critical component of our water future it is important we approach its reuse in a way to avoid unintended consequences.
To learn more give us a call at 562-495-5777 or email our Alta experts. Jacqueline.McMillen@Altaenviron.com or David.Schack@Altaenviorn.com.
Blog post authored by Jacqueline McMillen, PE.