Roof-harvested rainwater irrigation of vegetables – is there a risk to human health?

(2011 – current)
Minna Tom

This project is linked to the Melbourne Water funded project: Turning rain into food – the benefits and performance of vegetable raingardens.

Harvesting of rooftop runoff (herein referred to as roof-harvested rainwater) is considered one of the best available methods to restore the natural hydrologic cycle. It is an old technology that has become an increasingly popular practice in urban Australia. However, research has demonstrated that the water quality of roof-harvested rainwater is highly variable and is governed by a number of factors including the roofing and distribution materials, weather patterns and surrounding land uses.

Currently, there is a lack of guidelines that specify the range of physico-chemical and microbiological qualities that are required for potable and non-potable applications of roof-harvested rainwater. This project focuses on addressing knowledge gaps regarding the use of roof-harvested rainwater to irrigate food crops.

This study aims to investigate whether microbiological and chemical contaminant concentrations in root, fruiting, leafy and herbaceous vegetables irrigated with roof-harvested rainwater are significantly greater than vegetables irrigated with potable mains water. It will also assess whether any contamination present poses a short or long term risk to human health.



This study will use vegetable raingardens established in a typical urban backyard and within a controlled laboratory setting as the basis for the investigation. The findings of this study will be used to inform the Melbourne Water funded project titled ‘“Turning rain into food; the benefits and performance of vegetable rain-gardens”.

Project Partner:
Melbourne Water

Dr David McCarthy and Prof Tim Fletcher

Publications (link)

Turning rain into food – the benefits and performance of vegetable raingardens (Vegetated Filtration Systems/Biofilters) WSUD Technologies