Wednesday, July 24, 2013

Building Our Wooden Rainwater Cistern

 Here in north Texas we experience frequent dry conditions in the summer.  We built a rainwater collection cistern out of western red cedar and use the collected water for irrigating our trees and landscaping.  The cistern holds 3000 gallons of water and is approximately 8 feet tall (not including roof height) and 8 feet in diameter.  It drains approximately half of our roof, which is approximately 1600 square feet.  Although not exact, our observations are that for every 1" of rain, the tank fills up about 2 feet - so 4" of rain would fill it up.    

My husband wrote a book about how to build cisterns similar to this one.  

You can purchase it at:

Below are some pictures of it under construction.

It rests on a concrete foundation that is approximately 8 1/2 feet square.  It has 28" outer beams and one inner beam.

Below is a description of some of the key points of building the cistern.

 Using a jointer to machine one straight edge on the staves.
 Using the table saw to machine a parallel straight edge to the one machined on the jointer.

 Using a router and a jig to cut a dado (groove) on each stave to fit around the cistern floor.
Lining up a jig on the stave to mark the holes for the dowels that are drilled (next 3 pictures).



Using a drill press to cut holes on the floor boards for the dowels that hold them together.

Putting the floor together using dowels.
The floor is placed on the 4" X 6" and 6" X 6" grid that supports it and keeps it off the concrete foundation. 

Putting the staves together. 

Building the roof on temporary short staves while supporting the center post. 
Detail showing the temporary short staves that support the roof joists.

 This is the center post which also provides ventilation to the roof. 

Supports that hold the plywood roof sections in place until they are screwed to the joists.

 Detailed view of the side of the roof panels showing the beveling.

The finished (and freshly stained) new cistern!

Not shown in the pictures is the installation of a made-to-fit food grade plastic liner.

The hoops holding the staves together were made from mobile home tie downs.  We chose them for their high strength and because they were galvanized and relatively inexpensive.

Also not shown is the plumbing from the roof to the cistern.  We used 3" and 4" PVC.  It is plumbed from the roof gutter.  We drain the cistern in the winter to prevent freeze damage. 

See the video below for 3-D model of the cistern being constructed.

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