Smoke Testing of the Wastewater Network

Hauraki District Council occasionally tests the district’s wastewater network using smoke. This is a process called 'Smoke Testing'. Smoke testing involves pumping smoke into the wastewater network through selected manhole covers and keeping track of where it emerges.

This testing is a method used to find breaks, defects and clean stormwater/surface water entering the network, which can potentially overload the system. Smoke testing is a common practice to help find faults and keep stormwater out of the wastewater network – which in turn makes treating the wastewater more efficient and cost effective.

What is the 'smoke'?

The 'smoke' we use is actually a type of vapour and is the same non-toxic substance used in smoke machines for concerts and shows. It is considered safe for humans, animals and plants. The smoke leaves no residue or stains and will disappear rapidly with ventilation without leaving an odour if it does enter a dwelling.

Before smoke testing commences, we notify the residents by way of:

Letter drop to all houses in the affected area.
Posting on community Facebook group pages

How does smoke testing work?

Smoke testing works by pumping the smoke via a machine into selected wastewater manhole covers, the smoke then fills the main wastewater pipe and any connecting pipes following the path of any leak to the ground surface or cross connections. On-site staff monitor where the smoke escapes the network and records the data for potential upgrades and repairs.

What should I do if smoke gets into my house?

Do not be alarmed as this can happen on occasions due to unknown plumbing issues. (This smoke is non-toxic).
Open windows and doors to allow ventilation and note where the smoke is coming from. The smoke will clear in a few minutes, and you can leave your home to notify one of the staff members if they have not come to see you.
If you have any doubt as to the source of the smoke in your home or it has a burning smell do not hesitate to call 111.

What should I do to prepare for smoke testing?

Check all drain traps contain water. To do this run all taps for 30 seconds and flush toilets. (A “trap” is a U or S shaped section of pipe in your private connection that is designed to fill with water, to stop wastewater gases and smells entering your home through sinks and other drains).
If there is an individual in your home with respiratory or mobility limitations, please notify one of the contacts on the notification letter.

Where does the smoke appear?

Smoke will be seen coming from:

Roof terminal vents on homes.
Stormwater downpipes, sumps or drains
Manhole covers
Building foundations
Holes and cracks in the ground

What happens after the smoke testing is completed?

Council may use the findings and data to help plan any future infrastructure projects and to identify changes required to stop stormwater and other surface waters from entering the wastewater network.