Why gutter debris should not reach the tank
A rainwater system collects everything washed from its roof catchment. Leaves, dust, ash, animal droppings, insects and roofing debris can enter the gutters, then move into downpipes and tanks. Screens and first-flush devices help, but neither replaces routine roof and gutter maintenance.
Leaves and silt can clog inlets, pumps, filters and irrigation outlets.
Organic matter and droppings can affect colour, odour and microbiological quality.
Damaged screens and gaps give mosquitoes access to stored water.
Identify and isolate every tank-fed downpipe
Do not start flushing until you know where each downpipe goes. Some systems feed a tank directly; others use a wet or charged line that holds water below gutter level.
- Trace the system.Identify every roof catchment, downpipe, first-flush device, filter and tank inlet.
- Choose the correct isolation point.Use an installed bypass or diverter where available. Otherwise a removable connector may be disconnected by a competent person without damaging seals or pipework.
- Direct runoff safely.Send debris and wash-water to a stable area or suitable container, away from the tank, building footings, neighbours and stormwater pollution risks.
- Clean and flush.Remove gutter debris first, then flush accessible downpipes until the discharged water runs clear and flow is unobstructed.
- Discard the dirty first runoff.After reconnecting, allow the roof and device to shed the contaminated first portion according to the system design.
- Reconnect and check.Restore connectors, screens and caps; inspect for leaks and confirm the tank inlet is protected.
Do not improvise: If the connection is glued, inaccessible, under pressure, part of a charged line or difficult to identify, stop and use a plumber or rainwater-system professional.
Why some systems need extra care
In a charged system, parts of the downpipe network remain full of water. Disconnecting a fitting can release stored water and sediment, and the tank may not be isolated simply by moving the visible inlet pipe. Locate the drainage or clean-out point and follow the installed system design. If there is no safe, obvious diversion method, a plumber should handle the isolation.
Five layers of debris control
- Suitable gutter protection: metal leaf mesh can reduce large debris, but still needs inspection and cleaning below or behind it.
- Leaf-exclusion devices: downpipe rain heads or screens catch larger material before it enters pipework.
- First-flush diversion: a maintained device discards the most contaminated early roof runoff.
- Tank inlet screen: a clean, intact screen keeps insects and remaining debris out.
- Point-of-use treatment: filtration or disinfection must suit the intended use and current SA Health advice.
There is no universal first-flush volume. Roof area, contamination, rainfall, local environment and device design all matter. Follow the manufacturer's sizing and maintenance instructions and seek professional advice for drinking-water systems.
Screen every opening
- Fit intact mosquito-proof mesh with openings no greater than 1 mm to tank inlets and overflows.
- Keep inspection hatches closed and seal unintended gaps around pipes and lids.
- Clean screens so water can enter and overflow without bypassing the mesh.
- Replace torn, corroded or poorly fitting mesh.
- Remove nearby containers or pooled water that can also support breeding.
If larvae are present: follow current SA Health or council advice. Treatment choices depend on how the tank water is used; do not add an unapproved chemical to drinking water.
Inspect the whole collection path
| When | What to inspect |
|---|---|
| At least annually | Roof catchment, gutters, downpipes, screens, first-flush parts, filters, tank lid and overflow. |
| Twice yearly or seasonally | Properties under gums, pines or deciduous trees; sites with frequent leaf fall or bird activity. |
| After storms or ash fall | New debris, damaged screens, blocked outlets and contaminated first runoff. |
| Before a professional clean | Tell the cleaner which downpipes feed the tank and how the system is isolated. |
| After the clean | Confirm reconnects, seals, screens and flow before returning the system to service. |
Tank-aware gutter-cleaning checklist
- All tank-fed downpipes identified
- System type understood
- Tank feed safely isolated or diverted
- Dirty water directed away from tank
- Gutters and accessible outlets cleared
- Downpipes flushed until clear
- First dirty runoff discarded
- Inlet and overflow mesh intact
- First-flush parts cleaned and reset
- Connections restored and checked
Tell us about the tank when you request a quote.
Koala Contractorz can plan careful downpipe handling, isolate straightforward tank feeds where practical and supply completion photos. Complex charged systems or plumbing alterations may require a licensed plumber.
Read the current South Australian advice
Rainwater tank FAQs
Should I disconnect my rainwater tank before gutter cleaning?+
The tank feed should be isolated or diverted so leaves, silt and dirty wash-water do not enter the tank. The correct method depends on whether the system has a diverter, wet or charged line, removable connector or another plumbing arrangement.
How much water should a first-flush device divert?+
There is no safe universal 20–50 litre setting. The required diversion depends on roof catchment, local contamination, the device and how the water will be used. Follow the device instructions and relevant SA Health or plumbing guidance.
How do I stop mosquitoes breeding in a rainwater tank?+
All inlets, overflows and access points should be sealed or fitted with intact mosquito-proof mesh. SA Health guidance calls for mesh with openings no greater than 1 mm. Replace damaged screens and remove nearby standing water.
How often should tank-fed gutters be cleaned?+
At least annually is a common starting point, but roofs under trees or with heavy leaf fall may need six-monthly or seasonal checks. Inspect the inlet screen, first-flush device and filters at the same time.