06 April 2022

Should I Filter my Rainwater?

Do I really need to filter my rainwater for household use? Surely, when it just falls from the sky and is collected in a tank, what is there to go wrong? Are there any serious contamination risks, or can it go straight from tank to the drinking glass?

Water Tanks


So, you’re wondering whether it’s really necessary to purify your tank water. Maybe it seems a bit of an overkill to install a filter for something that comes straight from nature, and we understand where you’re coming from. But to ensure that your drinking water is pure and tastes great, we strongly recommend installing a filtration system.

And here’s why:

Contamination Happens

It’s inevitable: despite your best efforts, your rainwater will collect a certain amount of contamination from nature, even though it’s collected from your roof and flows directly into the tank.

Dust. Dirt. Organic Matter.

A certain amount of dust, dirt, bird poo and leaf litter collect on the roof and when it rains, this is washed into the gutters along with the water. Your leaf strainer will prevent most of this muck from entering your rainwater tank, but some small particles of debris and dirt get washed in every time. Of course, regular maintenance of the catchment area will go a long way towards harvesting clean water, but a certain amount of this contamination is unavoidable.


During winter, many folks notice that their tank water tastes ‘smokey’. The reason for this is pretty simple: if there’s woodfire smoke in the air when it rains, some of it washes into the tank and can contaminate the taste of the water.


In some circumstances, algae can bloom inside your rainwater tank, which will make the water change colour and taste weird. Depending on the type of algae, this can also be a serious health concern, so filtration is a must.

Acidic Rain

When compounds such as nitrogen dioxide and sulphur dioxide are released into the air, they rise to high altitudes and can mix with water in the atmosphere, causing acidic rain.

Although this water is unlikely to taste unusual, it can damage copper pipes and fittings over time. Admittedly, most modern homes are plumbed with poly pipes, but if you notice green/blue stains in your toilets and basins, this could be a tell-tale sign that your water is acidic.

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What Sort of Filtration System Should I Have?

There are plenty of options when it comes to household water filtration systems, and we recommend that you contact a filtration specialist for a professional solution for your home.

UV filtration is a simple way to remove bacterial contamination. This involves using an ultraviolet light to kill living organisms in the water, removing the threat of viruses and bacteria which can be transmitted through drinking water.

UV filtration is both effective and eco-friendly, but will not remove sediment.

Activated carbon filters are an effective way of removing sediment and reducing chemicals and removing bad tastes and odours, however, they will not get rid of bacterial contamination.

To ensure that your water is totally safe and clean, you may need a system which combines more than one type of filter. Talk to your specialist about this.

Do I Need to Treat All the Water?

Not necessarily. But you’re not intending to treat the entire household water supply, we recommend at least installing a point of use (under-sink) unit for drinking and cooking water.

These systems are generally inexpensive and will ensure that you and your family can enjoy fresh, clean and safe water all year round.

What Can I do to Prevent Rainwater Contamination?

As we mentioned before, a certain amount of contamination is inevitable. But you can help to keep your water pure and clean by sticking to a regular maintenance schedule.

  • Clean the roof - keep your roof free from dust, dirt, leaves, bird poo, dead animals, insects and anything else that could wash down into your tank.
  • Clean out the gutters - ensure that the gutters are free from leaves, sediment and stagnant water.
  • Clean the strainer - remove any leaves and build-up of organic matter from the leaf strainer.
  • Check the pipework - make regular inspections of the pipework to and from the tank. Fix up any cracks or breaks immediately.
  • Check the taps regularly - make sure they’re in good working order
  • Periodically empty and clean out your tank - your tank should only require cleaning out every 2 - 3 years, but this will remove any build-up of sediment in the bottom.
  • Test the water - domestic water testing kits are readily available from most plumbing and hardware stores and can help you identify any imbalances in your water.

Take Precautions

As they say, ‘prevention is better than cure’, so if you’re planning a roof refurb or a landscaping project that will create a lot of dust, take the time to disconnect your rainwater tank and cover the inlets before you start. This will prevent any chemicals or dirt from washing into the tank with the next lot of rain. Clean the roof thoroughly before you connect it all back up again.

Want to know more about filtering your tank water? Wondering where to purchase your filtration system, or simply want to have a chat about what type of system would be best? Send us a message here, or call us on 1800 752 784 for a chat with one of our team.

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