Rainwater Harvesting | Water Tank Supply | Tank Cleaning/Servicing
Covering Dorset| Somerset| Wiltshire and Devon | Nationwide Delivery for Tank Supply
Call Us For Rainwater Harvesting Advice or a Quote on +447737 691 746
RAINWATER CALCULATOR
Use our handy rainwater calculator below to calculate your average annual rainwater harvesting potential. It will also give you the recommended minimum tank capacity. Start your rainwater harvesting journey today and see how much you could save!
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Note: The average annual rainwater harvesting potential is calculated by multiplying the average local rainfall (mm) by the area of your roof (sq. metres).
Find Your Local Annual Rainfall in mm
Use the Met Office Annual Rainfall map to find your local annual rainfall is mm.
Rainwater tanks fill 3 times a year on average. To calculate the best tank size to purchase, divide the annual harvest potential in litres by 3 and round the number up to the nearest appropriate tank size.
We recommend rounding up to the nearest 100 if this number is under 1000 and to the nearest 500 if above.
i.e. if you average rainwater harvest potential is 12,500 litres, dividing this by 3 gives approx 4166 litres (assuming a tank fills 3 times a year)
Hence, this will require a minimum 4500 litre tank.
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Note: Above-ground tanks typically have a maximum size of 25,000 litres. This should be taken into account when calculating the ideal tank size. i.e. for a quarterly harvest potential of 50,000 litres, two 25,000 litre tanks will be required. Below ground tanks typically come in maximum sizes of 10,000 litres.
Rainwater harvesting systems can easily be expanded later down the line to increase capacity.
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If you want to get started but need a budget-friendly option, you can start with a lower amount of tanks and increase them later on.
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Whether you're planning a small garden set-up with water butts or looking to harvest rainwater in an agriculutral setting, it is almost always possible to expand your system as a later date.
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Expanding an existing system is relatively easy and as long as there is sufficent space.