Drain field rejuvenation in Victoria, and its limits
Jetting and aeration can genuinely restore a bed that is slow, and can genuinely do nothing for one that is sealed. Which you have is decided by probing before anything is sold.
Drain field rejuvenation works on biomat, not blinded soil
A working bed grows a thin biological mat at the soil interface, and that mat is part of how treatment happens. When it thickens past a certain point, usually because the bed has been overloaded, it starts restricting flow rather than treating it. That is a slow bed, and jetting the laterals plus aerating the trench can open it back up.
What does not respond is soil whose pore structure has been physically packed with grease and fine solids carried over from the tank, or compacted by vehicles. There is nothing to clear there; the pathway itself is gone, and that is a replacement.
Telling them apart is done by probing and by history: a bed that slowed gradually with a well-maintained tank is a candidate, and one that failed after years without pumping usually is not. The signs are set out on failure signs, and the tank side on outlet tee work.
Jetting laterals
How it works
How rejuvenation is approached
History and probing
Service history and trench probing first, because they say whether this bed is a candidate at all.
Fix the source
Tee, filter and distribution box put right first. Treating the bed while solids still arrive is wasted work.
Jet and aerate
Laterals jetted from the distribution box outward and the trench aerated, opening the interface where it can be opened.
Measure the result
Flow re-tested afterwards and the outcome recorded honestly, including where the improvement was smaller than hoped.
What to expect, and what not to
Years, not decades
Where it works, rejuvenation restores useful capacity and defers a replacement, sometimes by several years. It does not reset a bed to new, and any claim that it does should be treated with suspicion.
It also does nothing at all for a bed that is undersized for the house it serves, which is a design problem rather than a maintenance one and shows up as recurring saturation no matter what is done to the trenches. That case needs a larger system.
Where the site cannot support a bigger conventional bed, an aerobic treatment unit puts far less load on the soil and is sometimes the way to keep an existing bed in service. That is worth assessing before committing to a full rebuild.
On a bed that is slow because of biomat or silt, yes, and it can defer a replacement by years. On a bed whose soil has been physically blinded by carry-over solids, no. Probing decides which you have.
Service history and probing. A bed that slowed gradually on a tank that was pumped on schedule is a candidate. One that failed after a decade without pumping usually is not.
Nothing poured down a drain removes inorganic material from soil pores, and some products emulsify grease so it travels further into the bed, which makes things worse rather than better.
Years rather than decades, and it depends entirely on whether the reason the bed slowed has been fixed. Rejuvenating a bed while solids still arrive from the tank is wasted money.
Substantially, which is exactly why it gets oversold. That is also why we probe before offering it rather than after.
You are told that plainly, with the measured result, and the money spent is not recoverable. That risk is part of the conversation before booking, not after.
