Rainwater tanks have become increasingly common in many places of the world. Due to the decline in fresh water supply in many areas of the world, there is a sustained campaign for reduced usage of fresh water for domestic and commercial use, and adoption of alternative water sources and manmade storage systems. Rainwater harvesting systems have been identified as reliable alternative sources of fresh water. The systems are designed to capture rainwater in designated tanks for storage until it is needed, rather than using expensive mains water or relying on other sources of fresh water such as dams, lakes and rivers.

Rainwater collected from rooftop gutters can contain particles and debris like leaves or blossoms, eroded roof materials, dirt, bird and animal droppings. This material can clog pumps and the pipes that are intended to convey water to where it is needed. Apart from the problems of blockages, unfiltered rainwater can also contain dirt and tannins from plants that may cause damage to laundry or to the skin if used in showers or baths. Contaminated water can also make you sick if you are drinking it.

There are several ways we can prevent these problems, but one of the most convenient and easy means of keeping the rainwater in your tank clean is by installing a first flush diverter. This device is designed to prevent the initial runoff, which usually contains most of the debris on the roof, from entering the tank. Using a first flush diverter is smart thinking in regions that have an extended dry season followed by severe rainstorms. It is also valuable in heavily forested areas. In countries like Australia and New Zealand this piece of equipment is commonly used in rainwater harvesting, especially when the  tank water is used in the laundry.


First Flush Diverters can be installed above ground or in-ground. In-ground First Flush Diverters are more appropriate for sloping sites. Above ground or downpipe diverters should be installed before the tank inlet so that the first flush of water does not enter the tank.


A First Flush Diverter as used by Team Poly Tanks. This type of first flush diverter discards the first 60 litres of water and is suitable for tanks sized from 13,500 litres – 50,o50litres. The general rule of thumb is to discard 20 litres of water for every 100 square metres of roof.

However, while some areas or applications may not need to install first-flush diverters, others do and may need a sediment filter as well as a first flush diverter. First Flush Diverters are often combined with a Rainhead. Your plumber will help you decide what is best for your particular location and needs. A combination of these two is important if the rainwater is to be used for both doing the laundry as well flushing toilet cisterns. Sediment filters can be purchased with a 5 micron cartridge which is usually adequate for domestic use. Sediment filters are fitted after the tank and pump and before the tap outlets in the house so that the pump forces water through the sediment cartridge to filter out any sediment. The larger the sediment filter, the more litres per minute of water will flow through the system, from, say, 26 litres per minute for a small filter to 148 litres per minute for a large filter. Choose the size of sediment filter to suit your needs. Talk to the experts at Rainwater Tanks Direct. Remember that all filters will need to be cleaned regularly.

In summary, the amount of filtration needed for rainwater is dependent on the purpose for which the water is intended. Is it for residential purposes or is it for commercial purposes; and what outcome do you want to achieve? Simple small tanks intended for garden watering do not need the extra expense of an elaborate and complex filtration system. In suitable locations some people may need to use only the first flush diverters, if they need the water for doing the laundry. Others in heavily-treed or polluted locations may wish to have the security of a complete filtration system, including leaf-shedding rainheads, gutter leaf screens and a first flush diverter (all fitted before the rainwater goes into the tank as well as a post-tank post-pump sediment filter and even an in-house sophisticated carbon water filter especially if the water is intended for drinking purposes. Australian Health Departments always officially recommend against drinking tank water, even though some areas of rural Australia are totally dependent upon tank water for all their water needs, including drinking

Gutter Leaf Screens prevent leaves from clogging the downpipes.

While some people do not believe that rainwater can be filtered to the extent where it can be consumed or used for cooking there are however various filter systems that can effectively supply clean harvested rainwater suitable for any potable and domestic use. Rainwater harvesting systems have been of immense benefit to many people across the world. They can be very cost effective and have helped reduce domestic and commercial expenditure of individuals and corporate organizations alike by drastically reducing the water bill.

Choosing a supplier for rainwater tanks and accessories can be very difficult for people who don’t know much about the process. When there are several different suppliers to choose from, you may want to look at the warranty they offer, how their products differ from others, the sale price and the level of service you get.