When a septic system backs up, the first question is whether the blockage is a mechanical obstruction in the pipes or a capacity/absorption failure. When it is a pipe blockage, grease accumulation, root intrusion, compacted solids, or scale, two primary clearing methods are available: mechanical rodding and high-pressure water jetting. Understanding which method suits which situation, and what jetting actually involves, helps you make the right call and know what to expect from your contractor.
Quick answer (BLUF)
High-pressure water jetting (“hydrojetting”) uses water at 2,000-4,000 psi through a flexible hose with a jet nozzle to cut through grease, root masses, and sediment in drain pipes. It’s more effective than rodding for grease-based blockages and for clearing pipes that are heavily fouled rather than simply obstructed. It works on the pipes between the house and the tank, on the outlet line, and on distribution pipes to the absorption area, but it cannot rehabilitate a biomatted absorption area.
Rodding vs jetting: the key difference
Rodding (mechanical drain cleaning) involves feeding a rigid or semi-rigid rod or cable through the pipe to break up and push through an obstruction. It’s effective for discrete blockages, a solid object, a root cluster at a joint, or a localised compaction, and is typically lower-cost for simple blockages.
Jetting uses water pressure to do several things simultaneously:
- Cut through grease and scale deposits adhering to pipe walls
- Flush dislodged material forward and out
- Clean the entire pipe surface rather than just clearing a central channel
- Reach further into the pipe than rodding equipment typically can
Jetting is preferable when:
- The blockage is grease-based (grease adheres to pipe walls and reforms after rodding)
- The pipe is partially rather than fully blocked (a “slug” in a partially flowing pipe)
- The blockage is at an unknown location some distance from the access point
- The pipe has a history of recurring blockages (indicating generalised fouling rather than discrete obstruction)
- Root intrusion has caused spreading, fibrous blockage rather than a single root cluster
How the jetting process works
Equipment: A jetter unit consists of a high-pressure water pump, a water tank (or connection to a water source), and a drum of flexible high-pressure hose. The nozzle at the tip of the hose is engineered with forward-facing and rearward-facing jets. The rearward jets propel the hose forward through the pipe while simultaneously flushing dislodged material back toward the access point.
Nozzle types:
- Penetrating nozzles: High-velocity forward jet, suited for breaking up hard blockages
- Flushing nozzles: Primarily rearward-facing, suited for cleaning fouled pipes
- Root-cutting nozzles: Rotating blades or high-pressure radial jets that cut through root masses, used specifically for root intrusion work
The process:
- The operator locates the cleanout or access point, the house-side cleanout, an inspection riser, or the tank access
- The jetter hose is inserted and the pump started at lower pressure to navigate bends
- Full pressure is applied and the hose is advanced through the pipe, cleaning as it goes
- On retrieval, the hose is pulled back slowly, flushing dislodged material back to the access point
- The flushed material is collected in the tank access or pumped out at the cleanout point
Post-jetting: A CCTV drain camera inspection is often run after jetting to confirm the pipe is clear and to identify any structural issues that contributed to the blockage (root entry points, cracked pipe sections, joint offsets).
Where jetting is used in a septic system
House sewer to tank: The most common jetting application for residential properties. Grease accumulation and root intrusion are common in this section, particularly in older clay or cast iron pipes.
Tank outlet line: The pipe from the septic tank outlet to the distribution box or absorption area inlet. If the outlet baffle has failed and solids have passed through, this pipe can become impacted with solids and require jetting.
Distribution lines to absorption area: If the distribution pipes within or between absorption trenches are partially blocked, jetting can restore flow distribution. However, this does not rehabilitate clogged trench gravel or biomatted soil, it only addresses pipe blockages within the system.
Grease trap outlet pipes: Commercial food businesses benefit greatly from periodic jetting of their grease trap outlet lines, which accumulate grease deposits between cleaning services.
What jetting cannot do
Jetting is a pipe-clearing technique. It does not:
- Rehabilitate a biomatted absorption area, the soil permeability problem requires resting, new trenches, or system upgrade
- Fix structural pipe damage, cracked or collapsed pipes need repair or replacement, not just jetting
- Remove tree roots permanently, jetting cuts existing roots but does not kill the root system. Roots will regrow in the same location, typically requiring retreatment every 1-3 years unless the pipe damage is repaired or the tree is removed
- Replace a pump-out, if the tank is full, jetting the outlet pipe won’t help; the tank needs to be pumped before jetting makes sense
What to expect from a jetting service
A jetting service for a typical house drain to septic tank (20-40 metres of drain) takes 1-3 hours. The operator will:
- Advise on the likely cause after jetting (grease, roots, solids)
- Recommend follow-up if pipe damage is suspected (CCTV inspection)
- Advise on recurring blockage prevention (more frequent grease interceptor service, root barrier treatment, pipe repair)
Cost for a residential jetting service in the Hastings region typically ranges from $250 to $600+ depending on pipe length, access, and whether a CCTV inspection is included.
FAQs
Will jetting damage my old clay or cast-iron drain pipes?
At appropriate pressures, jetting is safe for clay, cast iron, PVC, and concrete pipes in good structural condition. Pipes that are already cracked or significantly deteriorated can be further damaged, which is why a CCTV inspection is valuable both before and after jetting on older systems. An experienced operator will adjust pressure for the pipe material and condition.
Can jetting clear tree roots from my septic pipes?
Jetting with root-cutting nozzles can cut existing root masses, restoring flow. However, it doesn’t prevent re-growth, roots regrow from the same entry points. If tree roots are a recurring problem, permanent solutions include: repairing or relining the pipe at the entry point, or removing the offending tree.
Is jetting the same as a “septic cleaning”?
No, though the terms are sometimes used interchangeably in marketing. “Septic cleaning” usually refers to a full pump-out plus interior tank clean. Jetting refers specifically to high-pressure pipe clearing. A complete service for a septic backup might include both: a pump-out of the tank, followed by jetting of the outlet pipe.
How do I know if jetting will fix my problem or if I need something more?
A licensed contractor will assess the symptoms to determine whether the blockage is in the pipes (jetting relevant) or in the absorption area (jetting irrelevant). After jetting, if the problem returns within days, the pipe blockage was masking an absorption area failure that needs separate assessment.