Effect of Treatment on the Quality of Harvested Rainwater for Residential Systems

Abstract

Rainwater harvested from four pilot-scale roofs (concrete tile, green, metal, and asphalt-fiberglass shingle) was batch-chlorinated to a target total chlorine 10 min residual of 2 mg/L as Cl 2 and passed through an activated carbon filter after 24 h to simulate treatment in a residential system. Total coliforms (TCs) were not detected, and the total trihalomethane (TTHM) concentration was typically (>85% of samples) below the US Environmental Protection Agency maximum contaminant level (MCL) of 80 μg/L in chlorinated-unfiltered rainwater harvested from conventional roofing materials. In contrast, TCs were always detected, and the TTHM concentration was 3-5 times higher than the MCL in chlorinated-unfiltered rainwater harvested from the green roof. The filter lowered the turbidity and TTHM concentration, but it also shed coliforms. Batch chlorination and filtration are more suitable potable treatment techniques for rainwater harvested from conventional roofs than from a green roof, but concerns regarding disinfection and turbidity remain.

Impacts of Municipal Water–Rainwater Source Transitions on Microbial and Chemical Water Quality Dynamics at the Tap

“…There are currently no national regulations for rainwater treatment for potable use. However, ARCSA/ASPE Guideline 63: Rainwater Catchment Systems , provides rainwater harvesters with suggested design criteria and water treatment goals. None of the physical and chemical parameters examined for the rainwater in this study exceeded US EPA health and aesthetic-based drinking water limits, if present.…”

“…Previous work has focused on chemical and microbial characteristics of rainwater prior to and immediately after treatment, ,,, but this study provides unique insights about the role of rainwater quality as it flows into and interacts with building plumbing. The results indicate that building operators should understand and be prepared to contend with the potential consequences of corrosion and metal release, as well as increased microbial proliferation following a water source transition between municipal water and rainwater.…”

Decision making for implementing non-traditional water sources: a review of challenges and potential solutions

“…For example, a study by Fuentes-Galván et al 33 in Guanajuato, Mexico, concluded that further treatment was required before consumption. Keithley et al 34 found activated carbon filtration followed by chlorination produced high quality potable water. Therefore, on-site testing and maintenance of RHRW collection and storage systems is suggested before recommending strategies for safe non-potable and potable water use or consumption.…”

Rainwater harvesting potential in a semiarid Southern California city

“…LID devices, such as rain barrels, have long been used for rainwater harvesting in many parts of the world where annual rainfall is moderate to abundant (Australia—Rodrigo, Sinclair, & Leder, ; Huston, Chan, Chapman, Gardner, & Shaw, ; Wang & Blackmore, ; Bangladesh—Karim, ; Brazil—Pacheco, Gomez, Oliveira, & Teixeira, ; Europe—Palla, Gnecco, Lanza, & La Barbera, ; Malaysia—Lee, Mokhtar, Hanafiah, Halim, & Badusah, ; Nigeria—Aladenola & Adeboye, ; Korea—Han & Mun, ; Italy—Liuzzo, Notaro, & Freni, ; United States—Keithley, ; Fricano & Grass, ) as well as in areas with semiarid to arid regions with low annual rainfall (Bakir & Liang, ; National Institute of Hydrology, ; Li, Gong, & Wei, ; Kahinda, Rockstrom, Taigbenu, & Dimes, ) and as an alternative source for potable and nonpotable water use (i.e., lawn irrigation, crop production; Imteaz, Adeboye, Rayburg, & Shanableh, ; Thomas, Kirisits, Lye, & Kinney, ; Boers & Ben‐Asher, ). This reduces water bills and saves energy used to produce and transport water, thus making it a viable strategy for supplementing local water supply both in areas with higher or lower risk of water scarcity (Dallman, Chaudhry, Muleta, & Lee, ; Ruberto, Lee, & Bayer, ).…”