Rainwater harvesting tips to maximise every drop

April 7, 2025

Anyone living on the land knows that rainwater isn’t just a backup, it’s most of the reason the house works. Filling troughs, watering the veggie patch, keeping the washing going without thinking about it. And when the tank runs low, that’s a scramble nobody enjoys.

The good news is that most of the water people lose is lost before it ever gets near the tank, which means the fixes are cheap and they’re mostly at roof level. Here’s what actually makes a difference.

Start at the top, because clean gutters change everything

A blocked gutter will quietly cost you thousands of litres over a wet season, and you won’t see any of it happen. Keep them clear of leaves and gunk, particularly after a storm, and check the downpipes as well as the run of the gutter itself. A downpipe packed with leaf litter undoes all of it faster than you can say stormwater runoff.

Gutter guard is worth the money if you’re under trees. It’s a fiddly afternoon to fit and then it catches the big stuff for years, which beats the alternative of getting the ladder out every few weeks.

The roof and where the tank sits

What your roof is made of changes what ends up in your water. Colorbond and galvanised steel are good catchments and they don’t shed much into the flow. If you’ve got a roof with old lead flashing on it, or a painted surface that’s chalking, that water is worth a conversation with a plumber before you drink any of it.

For the tank itself, shade helps. It slows algae growth and it keeps the water cooler through a run of hot days. Group tanks together if you’re putting in more than one, because it makes the overflow and the pump plumbing far simpler. And put the whole lot on a level, stable base, because a full tank is very heavy and a base that settles on one side is a genuine problem.

First flush diverters

A first flush diverter sends the first part of each downpour, the part carrying bird droppings and dust and ash off the roof, away from the tank instead of into it. That first wash is where nearly all the contamination is, so diverting it cuts the problem out near enough at the source.

You’ll also clean the tank far less often, which is nobody’s favourite Sunday job. Size the chamber to your roof area and empty it after each event, because a diverter full of last month’s water is doing nothing for you.

Then protect what you’ve caught

Tank inlets, outlets and overflows are the places contamination gets in. Every opening wants insect-proof mesh on it, fitted properly and checked once a year, otherwise you’ve built a mosquito breeding site with a lid on it. The overflow needs mesh just as much as the inlet does, and it’s the one people forget.

Send the rest of it into the garden

Not all of it has to be stored. Redirecting overflow and runoff into the orchard or the windbreak plantings puts it where the roots are instead of sending it down the driveway. Shallow swales or a trench along a path let water soak in rather than run off, which keeps the trees going and cuts erosion at the same time.

Pumps

A pump is the part of the system that decides whether any of this is usable. If yours is wheezing more than it’s pumping, or cycling on and off when nothing’s running, you’ve got a leak or a failing pressure switch and both get worse if you leave them. Run it once every few months over winter rather than letting it sit for half a year, and know where your isolating valve is before you need it.

The overflow plan

When the big rain comes, the question stops being storage and becomes where the excess goes. An overflow piped neatly downhill, or into a gravel soakage pit well away from the house, protects your footings and your veggie garden both. An overflow that just dumps at the base of the tank will eventually undermine the tank stand, and that’s an expensive way to learn it.

Maintenance is the whole secret

None of this runs well if it’s ignored for months. A gutter check each season, a tank inspection before summer, and a pump test every few months will catch small problems before they grow teeth. Put the reminders in your phone, because the system only fails on the day you needed it.

Last thoughts before the next storm rolls in

An acreage asks a lot more of its water system than a suburban backyard ever will, and that’s part of what makes it satisfying. A setup that works gives you real independence and the confidence to go through a dry stretch without flinching at the forecast. A bit of effort up front saves you a water truck call-out later, and that’s a trade worth making.

Shop related products

Gutter guard protector, 1 metre length. Keeps leaf litter out of the gutter and the downpipe.
Soudal all purpose silicone, charcoal, 300ml. For sealing a downpipe joint that’s weeping.
Pope Simple Set tap timer. So the tank water goes on the garden at the right time of day.
Pope 12mm brass tap adaptor, 20BSP. The fitting that connects a hose to a tank tap properly.

Did you know we also stock gutter, downpipe, elbows, pops and brackets in Colorbond, Zincalume and galvanised in the shop, cut and supplied to suit your job. Most of it isn’t listed online, so give us a ring on (08) 8536 4333 to talk through sizes. There’s more watering gear in our Pope range.