Understanding the levels of water ingested while using high pressure spray devices will help to determine future water recycling guidelines.
Recycled water is an essential part of future water management strategies in Australia.
The Australian Guidelines for Water Recycling (AGWR) set regulatory targets for public health protection on the basis that, even during non--?potable uses, small quantities of water will be inadvertently ingested from exposure to sprays and aerosols.
Requirements for water treatment are calculated to reduce the risks of illness from exposure to enteric pathogens to tolerable levels. However, assumptions on the volumes of water inadvertently ingested have little evidentiary basis and are essentially expert opinions of quantities thought to be plausible.
The Car Wash Study performed was designed to find out how much water people accidentally ingest when they wash a car with a high pressure spray.
The specific objective of the project was to measure inadvertent water ingestion during washing of a hard surface using a high pressure device. This activity was chosen because of relevance to water reuse in both domestic and occupational contexts, and because it involves relatively high intensity exposure likely to result in ingestion of measurable volumes of water.
The researchers added a non-toxic chemical to tap water and asked volunteers to wash a car replica, then collected their urine for the next 24 hours. By measuring the amount of chemical found in the urine, the researchers calculated how much water the subject ingested during the car washing activity. The project was performed in collaboration with Monash University and funded by Water Research Australia.
The project generated the first empirical quantitative data on indirect water exposure. This will be included in future revisions of the AGWR, and enable better risk assessment.
Dr David Halliwell, CEO of Water Research Australia, said “This unique and innovative project means the water industry can now reliably estimate human exposure to recycled water use in high pressure spray devices. This leads to a more efficient treatment outcome, and therefore, an improved customer value proposition. This technique can be extended across many other water exposure scenarios, which may greatly improve the cost effectiveness of water treatment for some water recycling scenarios.”