Rainwater Tank Problems

Rainwater Tanks aren’t always trouble free, so here is some advice on a couple of problems that you can encounter.


Even with pre-filters there will eventually be a build up of dirt and cloudy water at the bottom of the tank.

There are professional tank cleaning companies that will provide the safest way of cleaning a tank. As they can filter the water out of the sludge they minimise the water lost from your tank.

If you are going to do it yourself the best time is to do it when the tank is low. Working from out side the tank use a pressure washer to wash the sides and agitate the sludge in the bottom, then flush it out of the drain.

Whatever you do DO NOT Climb Inside The Tank.  Working inside tanks (known as Confined Space Work) is a very risky thing and several people have been killed.


Regular chlorination of your rainwater tank should not be necessary, although there will be some bugs in the water you will develop an immunity.

However if people are getting ill, or you suspect the water in your tank is contaminated you can chlorinate the water.

If you are going to be getting elderly or small children visiting who are used to drinking town water it can be sometimes safer to chlorinate before they come. it would be sad if your visitors became ill because they weren’t used to drinking tank water.

To chlorinate add either swimming pool chlorine (calcium hypochlorite 60-70%) or sodium hypochlorite (bleach) 12.5% by volume.

The dose to treat the contamination should be 7 grams of calcium hypochlorite or 40mL of sodium hypochlorite per 1000 litres of water in the tank at the time of treatment.

Rather than just add the chlorine fill a plastic bucket with water to 2/3 full and then add the chlorine, in the open air.

DO NOT add Water to Chlorine. Empty the bucket into the tank, being careful not to spill it, and then mix the contents of the tank.

An easy way of mixing if you have a pressure pump is to put a hose into the tank and leave it running for 15 – 20 minutes.

Once the water is mixed leave it to stand for at least 24 hours to allow the chlorine taste and smell to dissipate.

Have you had rainwater tank problems?


For more about tank water quality see Rainwater Safety

For similar posts see Sustainability


1 Comment

  1. Caitlyn Plowman

    It took me time to read all the tips, and I loved the posts.

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