Rainwater Tank Maintenance: Keeping Tank Water Clean

A rainwater tank is not a set and forget thing

Most people put a tank in, hook up the downpipe, and then never think about it again until something goes wrong, which is fair enough because it looks like a sealed box that fills itself. It is not quite that. Whatever lands on your roof ends up in there, and over a few years that adds up in ways you do not see from the outside.

None of what follows is hard. It is just the stuff nobody tells you when the tank goes in.

What is actually sitting in the bottom of it

Sediment settles out and forms a sludge layer on the floor of the tank. Leaf litter breaks down in there. Algae will grow anywhere light gets in, which is why a translucent tank in full sun is a different proposition to one in the shade. And occasionally something gets in through an unscreened inlet and does not get back out.

If that water is going to a garden it is mostly a nuisance. If anyone in the house is drinking it, it matters a lot more, and a screened inlet plus a clean out every few years is the whole of the job.

Your gutters decide your water quality

This is the one worth acting on, because it is upstream of everything else. The gutter is the feed line into your tank, so whatever is sitting in the gutter is what is going into your water the next time it rains properly. Leaves, roof grit, bird mess, all of it.

Gutter guard is the cheapest fix on this whole list. It keeps the bulk of the leaf out, which means less sludge in the tank and fewer blocked downpipes in a heavy downpour. Clear the gutters before the first decent rain after a dry stretch and you will be well ahead.

It runs out faster than you expect

Everyone underestimates this the first year. A long dry stretch, a few extra people staying, a slow leak on a fitting you have not looked at, and suddenly there is a lot less in there than you assumed. Knowing roughly what your household uses against what your roof actually catches is worth ten minutes with a calculator, and it is the difference between planning a top up and making an urgent phone call.

Plastic, steel or concrete, and what changes

Poly tanks are light and cheap and easy to move, and they want UV protection, so keep an eye on one that has been baking in full sun for a decade. Steel is tough and has a liner in it that does the real work, so a liner that has gone is worth knowing about early. Concrete lasts a long time and can shift the taste of the water a little depending on how it was sealed.

None of them is wrong. They just fail in different ways, so it is worth knowing which one you have.

Overflow is the one that damages the house

Puddling around the base of a tank is not a small problem. Water that keeps sitting there will soften the ground under the tank, wash out around footings and turn the area into a bog, and a full tank is heavy enough that you do not want it sitting on soft ground.

The overflow needs somewhere to go that is away from the tank stand and away from any building. Get that right once and it looks after itself.

The short version, in order

• Screen the inlet, so leaves and animals cannot get in.
• Guard and clear the gutters, because that is where the dirt comes from.
• Check the tank for cracks and check the fittings for weeps, particularly around the outlet.
• Get the sludge out every few years if the water is being used in the house.
• Send the overflow away from the stand and away from the walls.
• Keep a rough idea of your level, so a dry stretch is something you planned for.

Shop related products

• Renew 20mm Hose Cock Male Rough Brass. A solid brass outlet tap, which is the fitting that gets worked hardest on a tank.
• POPE 12mm Brass Tap Adaptor 20BSP. Gets a garden hose onto a tank tap without it weeping every time you turn it on.
• POPE 12mm C/Grip 3 Piece Set. Hose connectors and a tap adaptor in one go, for the bits that always go missing.
• POPE 12mm Brass Universal Tap Adaptor. Fits the odd sized outlets that nothing else will sit on.

Did you know we also stock gutter guard, downpipe and downpipe clips, thread tape and silicone in the shop. Not all of it is listed on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf before you drive in.

Where to go next

• Plumbing. Fittings, taps, tape and the joining gear.
• Mt Lofty water exchange. Drop the empty, take a full one, which is handy when the tank is low and you still want decent drinking water.
• Setting up a backup water supply.
• Looking after the pump that moves it.

If you are not sure which fitting you are after, take a photo of the outlet and bring it in. Working it out at the counter takes two minutes and saves you buying the wrong thread twice.

Chat soon,
Candeece

I have learned most of what I know about tanks by getting it wrong first, so ask me anything.

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