Water tap

For those living in rural areas, the water supply may not always come from the local council. Many people rely on either bore water, river intake, water delivered by tankers, or rainwater to supply their domestic and stock water supply. This water is stored in tanks and tanks may be either plastic or concrete. Some tanks will be situated high on the property to allow the water to be gravity-fed, while rainwater tanks are situated directly beside houses or sheds. 

No matter where the tank is, or what it is made of, keeping the water in the tank clean is the top priority.

What do we mean by clean?

Clean water means that if you drink it, you will not end up afflicted by a gastro bug that sees you running for the toilet faster than the world’s fastest sprinter. Clean water means not having any chemical nasties in it that can affect the taste and purity of the water.

How does water become contaminated?

  • Roof surfaces can accumulate debris, bird and possum droppings, pollen, and other pollutants. When rainwater washes over these surfaces, it can pick up contaminants and carry them into the water tank.
  • Stagnant water in gutters and storage tanks provides an ideal breeding ground for bacteria, algae, and other microorganisms. 
  • Roof materials may leach chemicals into the collected water. 
  • Spraying pesticides or fertilisers can increase the risk of chemical contamination in rainwater.

How do we keep our water safe to drink?

The most important task is regular checks of what is in the tank. Debris from the roof, in the case of rainwater tanks, small animals falling in, like mice, and even a leak can introduce bugs into the water, so actually looking into the tank to make sure there is nothing there shouldn't be is imperative.

Physical cleaning of the tank

Once a year, the tank should be drained and a thorough scrubbing out of the tank should be completed. If you can’t access the tank, a flexible handle with a brush on the end is ideal - think chimney sweep brushes. Don’t use any cleaning product that can’t be safely rinsed out.

If you climb into the tank to clean it, make sure that someone knows you’re there and checks on you regularly.

If this sounds like hard work then many companies will clean your water tank for you or you can install a product like Tank-Vac that does this automatically.

Pre-tank filters

For rainwater tanks, filters are available that sit on top of the tank where the down pipe meets the tank and collect anything that comes off the roof before the water goes into the tank. These of course don’t filter out harmful bugs, but they are great at stopping detritus entering the tank in the first place, thereby making the water going into the tank much cleaner. Options include mesh screens, sediment filters, and cartridge filters.

There are also first-flush diverters that divert all the initial runoff from the roof each time it rains, washing away dust, debris, and bird droppings.

Chemical purifiers

There is a wide range of chemical purifiers on the market. You can get additives that don’t have chlorine in them, to those that do. It’s all a personal preference as to whether you mind your water tasting like a swimming pool!

Most additives come with test strips so you can see how much needs to be added and how effective it has been after the initial dose. There are too many chemical additives to go into here, but if you take a look online, you will find a vast array to choose from.

In-line water filters

There are many types of in-line water filters. You can filter water in the pipeline before it goes into the tank before it goes into the house, or use a point of entry filter - these are the sort that goes under your kitchen sink.

As with all products, not all filters are made equal, so it pays to do your research. The replacement filter cartridges also vary in price so check the costs of them too. The micron of the filter will determine what is kept out. Like the tanks, the filters are only as good as the person who checks them to make sure they haven’t clogged up.

Once you use a filter regularly, you will get to know approximately how often you need to change them. A lot depends on the quality of the water in the first place and how much sludge is in the pipes, to begin with. Water that has a lot of metals such as iron or calcium means the filters may need replacing more often.


An alternative to chemicals and filters is to install an ultraviolet sterilization system. The ultraviolet light kills bacteria and viruses that can be harmful to health.

A combination

To have extra clean water, there are hybrid models, which have both filters and a UV treatment system. The filters catch the sediments and metals, the UV kills the harmful pathogens. Once again, shop around for not only the best deal but also the most appropriate type for your situation.

To recap:

Keeping tank water clean can involve:

  • Chemicals
  • Filters
  • Ultraviolet sterilization systems. 
  • Elbow grease! With an annual clean-out of tanks

By understanding the risks of untreated water and implementing effective treatment methods, you can enjoy the benefits of sustainable water harvesting while minimizing potential ill effects. Investing in water treatment is an investment in the health and resilience of your household.