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Tuesday, May 7, 2013

How It Works: Rainwater Harvest

How it Works:  Rainwater Harvest

System Purpose.  Provide all water with no well or tie to water grid.

How It Works Summary.  Roof and gutter collects and directs rainwater to cistern where water is available on demand via a pump.  Several filters assure safety.   1” of rain = 1000 gallons for us.

System Cost.  $10,000 including installation.  Compare to $30,000 for well system.   Does not include cost of roof.   No water bill.  Minimal replacement costs (pump / filters).


System Components

Steel Roof collects up to 1000 gallons per inch of rain.  Steel roof minimizes particulate / organic build up and washes clean. 

Gutter and downspout directs water to first flush diverters.  Any standard gutter will suffice. 

First flush diverter “washes roof” by directing first 50 gallons into yard, then allows rainwater to pass on into cistern via buried PVC pipe.   This is the most important filter since the roof and gutter are always “dirty” (smoke, pigeon pooh, dust, leaves…).      Not effective on snowmelt, so we do not harvest during the long Minnesota winter. 

Cistern.   Stores and protects water.   Our 5400 gallon buried concrete cistern contains two manholes for maintenance and for adding emergency water.   Overflow pipe directs water downhill when cistern fills. Spring through fall, overflow is the “normal” state. 

Pump.  Provides high pressure water to house (faucets, shower) on demand.   

Filters.  All water is filtered 3 times.  A screen on the first flush diverter filters very large objects (leaves, bugs, seeds…).   First flush diverter “washes away” worst of “dirt”.  Cistern pump draws water through a floating 5 micron filter.  By floating 1 foot below surface, we get the cleanest water (sludge sinks, pollen floats).   Water for drinking is poured into Big Berkeyfilter and stored in Red Wing crock.   Big Berkey removes 100% of “bugs” and many others impurities, including Atrazine. 


System Maintenance.  Supply Red Wing crock drinking water with filtered water from Big Berkey.  Turn on / off first flush diverter (as needed).   Clean gutters and diverter screens.   Clean cistern every few years.  Fill cistern with water from milk truck in emergency.  Note:  it would be cheaper to get all our water from the milk truck than to drill a well.  Crazy huh???

Report Card.   Warm Season = A-.  Cold Season =  B+   (See blog post for details).

Biggest Challenge.  Not knowing how much water remains in cistern.  (See blog post for details).

Biggest success factor.  Composting toilet minimizes water usage.  Even low flow toilets leak.  (See blog post for details).    Irrigation water harvested off shed roof and stored in above ground tank.

The Connection.    Rain is a delight, especially the first rains after the long drought of winter, or any drought for that matter.    Like the plants on The Land, we thrive in the abundance of water, yet harvest no more water than is available by rain. 

1 comment:

  1. This rain harvest technique for save water looking very effective but the instillation of this system was very costly.i like this system and your blog very much. to please provides me some more information about any new and affordable technique.