STORMWATER DRAINAGE
Charged (wet) stormwater systems explained
A charged, or wet, stormwater line stays full of water between events so it can carry stormwater uphill to a higher discharge point. Because it holds water under pressure, it has rules an ordinary gravity line does not.
What a charged line does
An ordinary stormwater drain runs to empty by gravity. A charged line is the opposite: it fills with water and stays full, so the water already in the pipe lets the system push stormwater up to a higher point. That is how you get water from a low downpipe up to a tank inlet or a legal point of discharge that sits above the collection point.
Air and drainage points
For a charged line to work it has to be able to fill and clear. That means an air or vent point at the high end so air is not trapped, and a low point that can be opened and drained for cleaning and maintenance. A wet line with no way to drain it down is hard to service and is a common pull-up.
Pressure tightness
A charged line holds water under static head whenever it is full, so every joint along it has to be watertight, not just weatherproof like a gravity line. Pipe, fittings, and jointing are suited to staying full and under pressure, and the line is checked for leaks before it is covered. A weep at a joint that would be harmless on a dry line becomes a constant leak on a charged one.
The compliance record
Because a charged system is less obvious once it is buried, the record matters. Photograph the charged run before backfill, the air and drain points, the discharge arrangement, and any leak check. That set shows the line was built to hold water and can be serviced. Elemetric keeps that with the job.
Common questions
What is a charged stormwater system?
It is a stormwater line that stays full of water rather than draining empty. The standing water lets the system carry stormwater uphill, for example up to a tank inlet or a higher legal point of discharge, by filling the line until it spills out the high end.
Does a charged line need a way to drain and clear?
Yes. A charged line needs a low point that can be drained for cleaning and maintenance, and an air or vent point at the top so it fills and clears properly. Sealing it up with no drain or air point is a common failure.
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Download on the App Store →General information for licensed tradespeople, not legal or regulatory advice. The licensed plumber remains solely responsible for compliance. Refer to the current AS/NZS 3500 standards and the Building and Plumbing Commission (formerly the VBA) for authoritative requirements.