Frederick Jace
A rainwater harvesting tank is designed to collect and store rainwater until it can be diverted to wherever it’s required. This could be an outdoor tap for watering the lawn or washing the car, the washing machine to clean laundry, or a toilet for flushing.
However, when rainwater lands on your roof and passes through your gutters to reach your tank, it will likely pick up dirt and debris – including leaves, bird poo and moss – meaning an adequate filtration system is essential.
Installing a rainwater filter will remove contaminants to ensure that the stored water in your rainwater tank can be used safely and effectively.
There are several types of filters on the market – but the question is, which one should you choose?
To help you decide, let’s find out a little more about the different rainwater harvesting filters available.
Pre-tank filters
A pre-tank filter is designed to prevent debris from entering your rainwater tank at the very beginning.
It consists of a stainless steel element (usually mesh or a grill) that’s housed within a plastic body.
Anaerobic bacteria can lead to unpleasant smells, but a filtration system with finer mesh will usually inhibit such development.
Some pre-tank rainwater filters will require more cleaning than others – especially those with horizontal mesh – but they’re all relatively straightforward to maintain, as you don’t need to open up the tank just to clean the filter.
In-tank filters
Exactly as their name implies, in-tank filters are for installation inside rainwater tanks.
A filter sieve is positioned on an angle to ensure that dirt is continually rinsed away into the sewer – not into the rainwater tank.
This type of filter is typically used in conjunction with an overflow siphon and calmed inlet.
The overflow siphon ensures the best possible water tank quality by preventing contamination and eliminating odours. Whereas the calmed inlet ensures that water flowing into your tank doesn’t disturb the settled sediment at the bottom. The upward flow oxygenates the stored water, keeping it clean and fresh for longer.
Post-tank filters
Mechanical filters (such as the ones mentioned above) are great for removing particles from water, but bacteria and smaller particulate can easily slip through.
Although the water can still be used for WC flushing, washing machines and garden irrigation, it’s not safe for personal use (i.e. drinking, cooking, showering, etc.)
A particulate filter is typically installed to filtrate rainwater as it exits your tank. An ultraviolet light neutralises the health risk from bacterial sources and pathogens by destroying their DNA – instantly sterilising the water. The UV lamp will need replacing at least once a year, but it’s straightforward enough to do yourself.
If you intend to use rainwater for potable (drinking) applications, it’s worth considering a carbon filter. When water is passed through one of these, the taste and odour significantly improves. Carbon can also remove chlorine and other volatile organic substances (VOCs), making it safe for consumption.
Ready to buy a rainwater filter?
Now you know a little more about the different types of rainwater harvesting filters available, you should have a better idea of which will best suit your needs.
When shopping for filters, always go to a reputable supplier, as they provide only the highest quality products.
Take Cotterill Civils, for instance. They stock only the most reliable rainwater filters as part of their rainwater harvesting kits for 200m², 450m² and 800m² roof areas. They also guarantee competitive pricing and offer free delivery, helping you to save as much money as possible.
If you’re still unsure about which rainwater filter is right for you, or you have a question about rainwater harvesting in general, their experts will be more than happy to guide and advise you.
