18 Apr 2017

Do you know how much roof rainwater can I harvest?

1 Comment

The answer to this question depend on a number of variables. Including the size of your catchment surface,the annual rainfall amount and regularity for your area,and the efficiency of your rain water harvesting system.Briefly,a good rule of thumb for water harvest is 0.5 gallon of water for every square foot of catchment surface per 1’’ of rainfall.After check below example,you will see.

Example: If the roof measures 20’x60’(footprint),how much can I harvest per 1’’ rain?
Formula: Rainfall x Catchment surface x conversion factor = Supply
(Inches) (Square feet) (0.5) (Gallons)

1”x1,200 sq.ft. x 0.5=600 (600 gallons per inch of rainfall)

If the average monthly rainfall is 2.5” then how much can I harvest?

600gals x 2.5”= 1500 (1500 gallons could be harvest in a average month)

 Catchment surface(footprint of the building)


The total harvest water for any location over a period of time depend on the actual rainfall experienced during the period.Rainfall regularity will also play a part in determining the most efficient and effective storage capacity for a specific site.After harvesting and disposing,you can use them as toilet flushing,kitchen washing,watering the flower and grass,to save tap water.


Harvest roof rainwater is an aspect of Rainwater harvesting system.Different rainwater harvesting processes are targeted to effectively dispose the rainwater from different water catchments.This system use large amount of new patented and professional devices and materials are adopted to easily solve the special problems generated during harvesting rainwater,truly realize energy conservation,environmental protection,high service life and low cost.Our company can provide the heart part of Rainwater Harvesting System—Rainwater Harvesting Tank,want know more information please visit our website www.greening-solution.com.


One Response to Do you know how much roof rainwater can I harvest?
  1. Now you have clean water, it is time for the big step – the tank. You should know the approximate size of tank and type of tank. If not, please review the storage tank article and make this decision. Another tool you can use is this interactive tool – System Sizing Tool . You have now figured out the tank and how to get the water cleanly to it, the next step is getting the water out of the tank. A majority of times this will involve a pump and potentially a floating extractor .


Leave a Reply

Your email address will not be published. Required fields are marked *


We are glad that you preferred to contact us. Please fill our short form and one of our friendly team members will contact you back.