Did you know dogs' sense of smell is even more sensitive than the most advanced technological instrument?

This extraordinary talent is now being used by water companies looking for new ways to deal with the age-old issue of saltwater leaking into the wastewater system.

Sydney Water is Australia’s first water utility to employ wastewater leak detection dogs. Recently, the dogs Winnie, a cocker spaniel, and Ziggy, a springer spaniel, have been used to sniff out sources of saltwater ingress at Kogarah Bay in Sydney.

Saltwater ingress (SWI) has become a major issue for coastal wastewater treatment plants due to rising sea levels and ageing infrastructure. Many wastewater assets lie in tidal zones, allowing saltwater to enter wastewater systems through defects. This can lead to corrosion and premature wear to pumps and other sewer assets.

The team at Sydney Water soon discovered the dogs were extremely effective at sniffing out SWI. Winnie and Ziggy took 1.5 days to inspect around 2.5km of ground, and flagged 15 possible locations for saltwater ingress.

Video footage, photographs, and GPS information was collected to mark the dogs' locations, and then passed on to Sydney Water field crews for further investigation. Of the 15 locations, seven were confirmed by smoke-testing sewer assets and another six, along property connection points and gravity sewer mains, required further testing.

Dog training

During training, the dogs are taught to find sources of SWI while tracking along the tidal zone. When the dogs detect the smell of wastewater, they are then trained to drop their noses to the source and stay until their handler comes. The clever canines are then rewarded with a quick game of fetch.

Tidal zones in estuaries are dangerous environments for detection dogs and their handlers, so the team adapted the training and protocols to protect the dogs and improve performance. For example, the dogs are trained to wear high performance protective boots, allowing them to work and track among sharp oyster clusters, slippery rock platforms, and broken glass.

The science part

So why are dogs so much better at smelling than humans? Not only do they possess up to 300 million olfactory receptors in their noses, compared to about six million in humans, but the part of a dog's brain that analyses smells is about 40 times greater than humans too.

It is powerful enough to detect substances at concentrations of one-part-per-trillion— that's the equivalent of a single drop of liquid in 20 Olympic-size swimming pools.

Since June 2020, the wastewater detection dogs have assisted Sydney Water in investigating illegal carwash dumping of wastewater and trade-waste chemicals; domestic cross-connections between potable and non-potable water; stormwater and canal wastewater leaks; pressure mains leaks; collapsed maintenance holes; illegal discharge of septic wastewater; and located sources of odour complaints.

Now Winnie and Ziggy can add tracking and locating saltwater ingress to their ever-expanding repertoire of capabilities.