How does drain jetting work? In short, a purpose-built pump forces water through a flexible hose and out of a nozzle with precisely angled jets. The rear-facing jets drive the hose up the pipe and scour the pipe walls, while the forward jet breaks up whatever is blocking it. The result is a pipe that is cleaned wall to wall, not just punched through. This guide explains the process step by step, the nozzles a technician chooses between, what jetting will and will not fix, and when it is safe for your pipes.
Drain Blasters has been clearing drains in Cape Town since 2007, and drain jetting is one of the main tools on our trucks. What follows is how the job is actually done on site.
How does drain jetting work, step by step?
1. Find the blockage and the access point
The technician first works out where the blockage is and where the pipe can be reached. On most properties that means a gully, rodding eye, inspection chamber or manhole. Where the pipe is old, the blockage keeps coming back or there are signs of damage, a CCTV drain camera inspection comes first, so the operator knows what the pipe is made of and what condition it is in before any pressure goes in.
2. Choose the nozzle and set the pressure
The nozzle is chosen for the type of blockage (see below), and the pump is set to suit the size and material of the pipe. A good operator matches the pressure to the pipe, not to the machine’s maximum. Older clay pipes get a gentler setting than modern uPVC.
3. Work upstream from the downstream access point
Where possible, the hose goes in at the downstream access point and is worked upstream. That way the loosened debris washes back towards the opening, where it can be removed, instead of being pushed further into the system.
4. Break the blockage and scour the walls
Water leaving the rear-facing jets pulls the hose forward along the pipe. The forward jet cuts into the blockage, and the rear jets scrub grease, scale and silt off the full circumference of the pipe. The operator works the hose back and forth through the problem section rather than pushing straight through once.
5. Flush, remove and check
The hose is drawn back slowly while the jets keep flushing, carrying the loosened debris down the line. Heavy silt, sand or grease can be sucked out of the chamber with a vacuum truck rather than sent on into the sewer. On recurring problems, a second camera pass confirms the pipe is clear and shows whether there is damage that caused the blockage in the first place.
Drain jetting nozzles and what each one does
The nozzle does most of the work. Choosing the wrong one is the most common reason a jetting job clears a drain for a week instead of a year.
- Penetrating (forward-jet) nozzle: has a strong forward jet to bore through a solid blockage such as compacted paper, wet wipes or a grease plug.
- Rotating nozzle: spins as it travels, sweeping the jets around the pipe wall. It is the best choice for scouring grease and scale out of kitchen and commercial waste lines.
- Flushing nozzle: mostly rear-facing jets that move a high volume of water. It is used for clearing sand, silt and grit, which are common in Cape Town yard and stormwater drains.
- Root-cutting head: a water-driven cutter for root ingress. Light roots can be jetted out, heavy root masses need cutting, and the cracked joint they came through needs a longer-term fix (see sewage pipe root extraction).
Pressure versus flow
People tend to ask about pressure, but flow matters just as much. Pressure gives the jet its cutting force. Flow, measured in litres per minute, carries the debris away and keeps energy in the water over a long pipe run. A small machine at very high pressure can cut a hole through a grease plug and leave most of it on the pipe walls. A properly sized jetter balances the two for the pipe diameter, which is why a domestic basin waste, a commercial kitchen line and a large-bore industrial drain are each jetted with different equipment and settings.
What drain jetting clears, and what it cannot fix
| Problem | Does jetting fix it? | Notes |
|---|---|---|
| Grease and fat build-up | Yes | A rotating nozzle scours the full pipe wall. Commercial kitchens also need a working grease trap. |
| Silt, sand and grit | Yes | Common in yard and stormwater drains after winter rain. Cleared with a flushing nozzle and vacuum removal. |
| Soap scum and scale | Yes | Restores the full bore of the pipe rather than a narrow channel. |
| Wet wipes, sanitary items and foreign objects | Usually | The forward jet breaks them up. Hard objects may need to be retrieved. |
| Light root ingress | Yes, for a time | Roots grow back through the same cracked joint. |
| Collapsed or broken pipe | No | Needs an excavated repair or pipe relining. |
| Displaced joints or a sagging pipe | No | Jetting clears the debris, but the fault keeps collecting more. |
| Blockage in the municipal sewer | No | Report it to the City of Cape Town. |
Is drain jetting safe for your pipes?
Yes, when the pressure and nozzle suit the pipe. Modern uPVC, cast iron and sound clay pipes handle jetting well. The risk lies with pipes that are already failing: cracked or root-damaged clay, badly corroded cast iron, and older fibre pipes that can blister and deform. This is why the camera goes in first on older properties. Our guide on whether pressure cleaning is safe for older pipes covers this in more detail, and if the survey shows structural damage, see signs of a collapsed drain.
Signs your drains need jetting
- Water drains slowly from several fixtures, not just one.
- Sinks, showers or toilets gurgle when another fixture is used.
- There is a sewage smell from your drains or outside gullies.
- The same blockage keeps coming back after plunging or rodding.
- A gully or manhole overflows during heavy rain.
- A commercial kitchen line blocks between grease trap services.
Drain jetting versus rodding and chemical cleaners
Rods and drain snakes push through a blockage and restore some flow, but they leave the build-up on the pipe walls, so the blockage tends to return. Chemical drain cleaners can shift a minor organic clog in a single trap, but they do little to a main line, can damage older pipes and are hazardous to handle (see what chemicals are used to unblock drains). Wikipedia’s overview of drain cleaning methods sets out how the mechanical, chemical and water-jet options differ. Jetting is the method that actually cleans the pipe. For a side-by-side comparison of plungers, hot water, chemicals, rods and jetting, read our guide to blocked drain solutions.
Why drain jetting is a job for professionals
Pressure-washer drain attachments are sold for DIY use, but they are no match for a purpose-built jetter, and the risks are real:
- A high-pressure water jet can cause serious injection injuries through the skin.
- Jetting a sewer line can spray contaminated water back out of the access point.
- Too much pressure in a cracked pipe can turn a blockage into an excavation.
- Manholes and deep chambers are confined spaces that can hold hazardous gases.
Professional operators wear protective equipment, know which nozzle and setting to use, and can inspect the line before and after the job.
How often should drains be jetted?
Most homes only need jetting when there is a problem, or every few years where there is a known issue such as tree roots or a long, flat drain run. Restaurants, food processors and other businesses that send fats down the drain benefit from jetting as part of a planned maintenance schedule alongside regular grease trap cleaning. The right interval depends on volume and on how well the grease trap is maintained (see how often to clean a grease trap).
Frequently asked questions about drain jetting
How long does drain jetting take?
A straightforward domestic blockage is often cleared in a single visit. Time on site depends on access, the length of the line, the type of blockage and whether a camera survey is needed before and after.
Can drain jetting remove tree roots?
Jetting with a root-cutting head clears light to moderate root ingress. Roots get in through cracked or open joints, so they will grow back unless the joint is repaired or the pipe is relined. Our article on how tree roots affect your pipes explains why.
Does jetting damage pipes?
Not when it is done correctly on a pipe in reasonable condition. Damaged or fragile pipes should be inspected with a camera first, and the pressure reduced or a different method used.
Is drain jetting the same as hydro jetting?
Yes. Hydro jetting, water jetting and high-pressure drain cleaning all describe the same method. Read what is hydro jetting for more on the equipment, or see our high pressure drain cleaning service.
Drain jetting in Cape Town
If you have a slow or recurring blockage, Drain Blasters offers drain jetting services across Cape Town for homes, restaurants and commercial sites, with a CCTV inspection where it is needed. For an urgent blockage, see our drain clearing services.
