Rain water harvesting calculator

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THIS RAIN WATER CALCULATOR IS FOR INFORMATIONAL PURPOSES ONLY and using it, you understand that the results it provides can be inaccurate.

Do you harvest the rain water?

If so, you have my compliment. Don´t you harvest it yet? You should start doing it as soon as possible, otherwise you are losing your money.

First of all calculate your house floor area and put it in the form field below.

Input the house floor area.


Please, also specify if the area is in square meters (sqm) or square feet (sqft)
sqft sqm

Rain water for garden

Now let´s think little bit how the rain water can be used. First thing that comes to my mind is the garden. Instead of watering it with expensive drinking water why not to use the "free" rain water? It will reduce your water costs significantly as an average garden requires as much as 70 litres per square meter and year (1,7 US gallons per sqare feet and year).
Please, input the planted garden area that needs to be watered.


Please, also specify if the garden area is in square meters (sqm) or square feet (sqft)
sqft sqm

Rain water to flush the toilets

Really, the rain water also can be used to flush the toilet. Though it requires additional costs to modify the flushing system, these costs will be returned very soon.

How much water an average family flushes down the toilet daily (how much of expensive drink water can be saved)?

As much as 40 litres (10.5 US gallons) per person and day! Another considerable reduction of cost, isn´t it?
Please, input number of people in your family (using toilets).


Now go to WeatherBase.com, it is a website with historical weather information on almost 16500 cities all over the world, from latest 30 years. Find your nearest city and write down the annual precipitation rate.
Input the precipitation rate


Please, also specify if the precipitation is in inches or centimetres
in cm

If you wish to calculate the water costs savings please also specify the price of water (in US dollars) in your area
$

Please, also specify if the price is per Kgallon (1000 gallons) or cubic meter (1000 litres)
Kgallon cmeter

Calculator gives you an estimation of how many gallons or litres of rain water can be potentially harvested as well as money you can save if collecting the rain water.