How jetting works
A hose with a purpose-made nozzle goes into the drain through the gully trap or an inspection opening. Jets angled backwards drive the nozzle along the pipe, while jets facing forwards break up whatever is in front.
A drain machine punches a hole through a blockage. Jetting, by contrast, scrubs the whole circumference of the pipe, which makes it the usual pick for grease, scale and silt, and for flushing out roots once they've been cut.
Jetting cleans; it doesn't mend. If the pipe is cracked or has a sag, waste will start collecting again, and a camera inspection is how you find that out.
When jetting makes sense
- The same drain blocks every few months.
- A kitchen waste or gully trap is lined with fat.
- Silt or sand has washed into a stormwater line.
- Roots have been cut and the pipe needs flushing clean.
- A camera inspection or pipe relining is next, and the walls need to be visible.
What a plumber or drainlayer will do
Look before jetting
On older or fragile pipes, they'll often run a camera first to check the pipe can take the pressure.
Choose the nozzle
Different heads suit grease, roots and silt, so the choice depends on what's in the line.
Work along the line
They'll jet from the access point outwards, washing loosened debris downstream.
Prove it flows
Running water through shows the line is clear, and a second camera pass can show you the clean pipe.
What changes the job
- How long the drain is and how many bends it has.
- Whether there's an access point close to the problem.
- The build-up: a thin film of fat, or a pipe almost closed with it.
- The pipe's age and state, which can call for gentler settings or another method.
- Whether a camera inspection goes with it.
Who pays for jetting?
That turns on where the blockage is and on your provider's rules, which differ around the country.
Napier City Council says it won't pay for camera inspections or jet cleaning used to find the source of a problem, and asks you to contact it if a problem is found at the boundary. In Christchurch, costs on the council's section of a lateral are reimbursed only when footage proves a structural fault there and the council's reviewer agrees.
For other places, see who fixes a blocked drain and your city page, such as Napier or Christchurch. Our main blocked drains page covers clearing in general.
What you can do, and what to leave
You can
- Keep fat, wipes and food scraps out of the drains between visits.
- Uncover the inspection openings and clear a path for the hose.
- Tell the drain specialist about earlier blockages and pass on any footage.
- Unblocking a drain is on PGDB's homeowner list, though altering or repairing the inspection pipe or vent pipe is not.
Leave to an authorised tradie
- Running high-pressure jetting gear.
- Opening or refitting access caps and traps.
- Cutting roots before the jet goes in.
- Any repair the camera turns up.
Licences and consent
Opening up and repairing a drain both sit within the Act's definition of drainlaying, which is restricted work. Ask whoever turns up for their PGDB practising licence and check that it covers drainlaying; our guide shows how to check a PGDB licence.
Opening and putting back a purpose-made access point needs no building consent, unless it's part of a council or utility system. Like all consent-exempt work, it must still meet the Building Code.
Questions to ask before booking
- Will you run a camera before jetting, after, or both?
- Which nozzle will you use, and why?
- Is the pipe in good enough shape to jet?
- Can I keep the footage?
- What would stop the build-up returning?
What we would do
For a one-off blockage, a drain machine usually does the job. When the same drain keeps blocking, ask for jetting and a camera together: the jet cleans the pipe, and the footage tells you whether the pipe itself is the problem. Booking a third clear without knowing why the first two didn't last rarely pays off, so put that question to the drain specialist before they start.