Rainwater Harvesting -from other thread

[glenn-k]

If you had a use for it, you could really harvest a lot of water off of your shop roof, Harry.

[glenn-k]

A 40 x 60 roof - 2400 square feet would produce 35904 gallons per year with 24" of rain - last year we had over 55" - thats a lot.

[harry51]

The thought has crossed my mind!  Jenny loves rainwater for her flowers, her violets really thrive on it as compared to how they do on our flouridated, chlorinated city water down here. Naturally distilled seems to agree with them, and all her other stuff, too. I may set another big tank downhill from the shop and direct rainwater to it. If I could collect 24" of rain off the 2000 sqft. shop roof, and the same off the house roof, that would be nearly 6000 gallons.  I don't know why it wouldn't be potable if you kept it clean, and let the roof get washed off before tanking the water.

Another thing that may be worth looking at when we build the house is a greywater system that could irrigate outdoor plants. Mariposa county does have a greywater ordinance, but there are no real incentives (tax credits, etc.) connected with it that I am aware of. That would take quite a bit of the load off the septic system, for whatever that's worth.

[glenn-k]

Add another 0 to that , Harry 60,000 gallons.  The greywater ord. in the county has changed I think -- you have to go to one of the eco pond things now - I don't know what all but the health inspector said it was about more trouble than it was worth.  For myself I think I forgot to ask again.

[harry51]

You're right!  Clearly a caffeine deficiency here this morning! Left off one very important zero. It would be almost 60,000 gallons from both roofs! 7.48 gallons per cubic foot x 2, assuming 24 inches of rain per season could be captured and stored, x 2000 square foot roof = 29,920 gallons, and assuming equal rain capture off the similar sized house roof when it's done, would total  59840 gallons. That would water a lot of violets!

[glenn-k]

I think an excavated ferrocrete pond or epdm lined may be the way to go to store that much water.

I had my coffee but it was yesterdays so my answers may be a bit slow. :-/

I guess I better - somewhat reluctantly head down the hill and complete my septic system and leach lines so I can afford to be here -- yeah --a real job.

[harry51]

I know where I might be able to get a used poly tank or two in the 5000 gallon category. Collecting rainwater in those for irrigation or whatever, and forgetting the greywater system and the plumbing complications it would require would probably make the most practical sense. I'm planning on having a full gutter system on the house to keep the roof runoff water from washing us off our perch, so it shouldn't be too hard to get some of it into a tank, and the rest into the pond, maybe.

[harry51]

Must be pretty good day-old! You're consistently beating me to the post this morning!  As you can probably see from there, it's misty/semi-foggy here this AM.

[glenn-k]

It was strong enough to put hair on my chest -- I moved the rest of this one to rainwater harvesting. I'm really with it-

[glenn kangiser]

I figure if I keep moving things around you won't know where to post!

[harry51]

I'm slow, but persistent!  Have a good one, and if you need a hand with that wood, let me know when you have time and I'll be the ground man inside the fence, or whatever would expedite the process.

[glenn kangiser]

Thanks Harry - I figured we had enough good information in this thread to make a rainwater one out of it.  I may try to pick up the oak tree this weekend. -- Hi Ho -hi ho -its off to work I go------ :-/

[Amanda_931]

Jonsey mentioned the BlueScope metal company--somebody else cruised the site and found their water subsidiary--and this .pdf file on their ideas of how to build a rainwater harvesting system--a lot more emphasis on keeping water out of storm drains--most of their products are certified for potable water collection:

http://www.bluescopewater.com.au/pdf/thinktank.pdf

Just to clog up your computer, there's this .pdf from Texas--I've put references to this on a couple of lists lately--maybe even this one--I know it's turned up here before:

www.twdb.state.tx.us/publications/ reports/RainwaterHarvestingManual_3rdedition.pdf

For no reason known to humankind, people tend to give figures for estimating the amount of water you can collect with extra steps--multiplying and later dividing by 100.  If collection were perfect (comes close with the Earthship^tm
systems, some of them are designed to allow comfortable living with less than 10 inches of rain a year) you could get a bit more than this, but with a moderately efficient collection system (not much through the overflow) and large enough tanks, .6 gallons per square feet under roof.  (ignore roof slope, count overhang area).  

[Daddymem]

There are the Rainstore units.  I have designed drainage sytems with these structures.  Those were $110/m^3 of water storage at the time.  The units install easily and have great strength.  With a polyethylene (30 mil please) you could store the water for use later.  You break out a column of these units and you have a place to drop a pump.  You cut and boot a pipe into the poly and you got inlet and outlets.  Now you can probably do a lot cheaper with tanks and all but these units provide a lot of design flexibility.  These were beginning to be stored around here and they are from out west so perhaps you can find them locally.