A Medium Sized Rain Water Collection System
We decided to do a medium size rain water harvesting project by
collecting water off the roof of our outbuilding shop/garage/barn.
The idea is that this manageable size system could provide water for
the garden and some trees, and that we could learn from it and decide if we
want to do a somewhat larger system using the house roof which provides
quite a bit more collection area.
2nd year update March 2013 -- a freeze problem..
One year update May 2012...
Overview
The shop building with its gambrel roof and the extension shed roof on
one side provides a total of 925 sqft of equivalent flat collection area.
We added gutters to the east and west sides to pick up the water, and
then ran PVC piping to a 2500 gallon plastic tank located under the south
end of the lean-to roof. If the 2500 gallons seems like
quite a bit of capacity, it initially seemed that way to us, but even in our
not very high rainfall area a thousand square foot of roof can harvest a
respectable amount of water.
The water collected by the gutters goes to an inlet at the top of the
tank. The plumbing has provisions for diverting the first few gallons of
each rainfall to eliminate some of the dust etc. that accumulates between
rainfalls. Water is removed from the tank via a fitting near the bottom and
pumped to the area needed with a 120VAC pump. There is an overflow pipe
that connects to the tank up high to run water off to some useful location
when the tank fills up and overflows.
The sections listed below give quite a bit of detail on the sizing and
construction, which is all pretty simple. There is a comments section
on the last page to ask questions and offer advice.
Table of Contents
Sizing the System
Collection (gutters and piping to tank inlet)
Delivery (plumbing and pumps to deliver water to
garden)
Overflow (system to manage overflow)
Performance
Comments (questions,
improvements, corrections...)
Gary July 3, 2011
