Water Tank Filter Comparison Chart

Comparison Chart of Pros and Cons of Rainwater Tank Purification Devices
Type of Device	Pros	Cons
1. Pre-TankFilter (Typically a sieve-like device that strains water before it gets to the tank)	• Stops larger debris from entering the water tank	• Quickly becomes clogged with debris and requires a lot of cleaning, often involving ladders
2. First Flush Diverter (A purpose manufactured container of about 20-30 litres in a vertical shape	. Diverts and discards the first 20 or 30 litres of rainfall down the drain resulting in the dirtiest water being rejected	. Only filters the small initial quantity of rainfall. Can become blocked itself (the chamber slowly drains after rain event)
3. Waterboy (Flexible tube, float and stainless steel device that is attached to the outlet pipe, inside the tank)	• Gathers water from just below the surface of the water level giving much cleaner water, free of sediment from the bottom. Never requires maintenance. Inexpensive.	• Needs to be installed inside the tank, i.e. water level must be low enough
4. In-Line Filters (Typically one or two large filters of about 4 litre capacity mounted near the pump or where the water line enters the household)	. Filter most physical impurities from the water. The first filter usually of a larger ‘micron’ filter and the second a smaller one	. Require regular monitoring and, depending on general surroundings, become clogged quite quickly resulting in less water pressure and increased pump strain. If badly blocked, can be a definite health hazard and finally filter cost is on-going and can be expensive
5. UV Light Treatment (A tube shaped device that works by subjecting water passing over it to strong ultra-violet light)	• Neutralizes any disease organisms present by damaging their DNA. This renders them harmless when consumed	Only works with clear, clean water. Doesn’t filter sediment, etc Requires electricity Expensive annual replacement of light bulb

6. Under Bench Filters (Smaller, very fine filters that typically target microbes or off tastes)	• Good for removing smells and tastes from drinking water (Activated charcoal) and disease organisms due to small micron rating.	Usually low flow because of filter density (not charcoal) and therefore susceptible to blockage with all but the cleanest water Easily neglected and therefore potential health risk (bacterial build-up)
Conclusion All filters are good in some ways (although with the pre-straining devices this is very debatable) however important factors to remember are: Maintenance time and costs. Are you capable of these or is it a job for a plumber and how often will they be required? A minimum of once per year is a given. Do you need to treat all of your water to a very high standard? Remember the vast majority of your water will be used in the bathroom, laundry, gardening and car washing etc.