A national review of hydrogen sulphide exposure, limits and controls in the water industry

Hydrogen sulphide (H₂S) is a naturally occurring gas that presents complex challenges for wastewater networks. Beyond its strong odour, it poses serious risks to human health and can corrode essential infrastructure.

From December 2026, Australia will adopt revised Workplace Exposure Limits (WEL) for airborne contaminants following a 2021 review of more than 700 chemicals, and Safe Work Australia is expected to decide whether to include reduced H₂S limits as part of a Regulatory Impact Assessment covering nine key substances.

To help inform this decision, in 2024 the Water Services Association of Australia (WSAA) brought together a working group, which included water utilities, regional councils, and Stantec specialists. Dominic Gibbs and Ari Shammay from our Water team in Australia collaborated with Pamela Sears, industrial hygienist based in Canada, and Deb Gray, a toxicologist from the US, along with James Goode from the WSAA. The team co-authored a paper reviewing the proposed changes in the Australian Water Association Water e-Journal.

The review found that although day-to-day H₂S exposure across the water industry is usually low, short-lived peaks and limitations in current monitoring technology would make strict lower limits difficult to measure or achieve. The paper also outlines the considerable operational and financial implications of adopting the proposed limits, and it presents an evidence-based alternative consistent with international standards.