Wastewater network SL-RAT inspections

The SL-RAT (Sewer Line Rapid Assessment Tool) consists of two small devices - a transmitter and a receiver - that are positioned inside manholes, at either end of a wastewater pipe.

The transmitter sends sound through the pipe and the receiver listens at the other end, analysing how the sound travels. If the sound passes through clearly, the pipe is open and free of blockages. If the sound is blocked, muffled, or distorted, this indicates there might be a build-up or blockage in the pipe.

The equipment itself stays above ground and does not go into the wastewater.

Most sections of pipe only take a few minutes to check and deliver real-time insights into the pipe’s condition.

If we’re carrying out SL-RAT inspections in your neighbourhood, you might see signage in the area, get a knock on your door and/or a receive a calling card or letter.

While these types of checks are more commonly carried out in commercial and industrial areas, we also do this in residential areas from time to time.

During an inspection you will see our team place one device at each of two neighbouring manholes. They temporarily remove the manhole covers, run the test and safely replace the covers.

If you’re nearby you might hear some faint musical tones, chimes, or buzzing sounds coming from the equipment. The inspections are completely non-invasive and only take a few minutes per section.