Rainwater Harvest

Started by jwv, January 20, 2006, 07:29:10 PM

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jwv

Hi Dustin,

I wish I could show pictures of our actual system but we no longer live in that house and I have no digital pictures of it. I kjnow my explanation was a little, hmmm, confusing. However, I did a search and found this site which shows a system very similar, in fact I tink we got our directions through this group in a roundabout way ( a friend who has a friend who has a friend)

http://www.caneloproject.com/dawn/dawn%20pages/workshops/water%20harvesting.html

judy

pg34-35 of this paper has an exact description of the system we used. WARNING-this is a PDF and may take a long time if on dial-up

http://cals.arizona.edu/pubs/water/az1344.pdf
http://strawbaleredux.blogspot.com/

"One must have chaos in one's self to give birth to the dancing star" ~Neitszche

Amanda_931

Got it.

There has been a rumor on another list or two that galvanized (zinc coated) metal is not good for potable water, although galvanized roofs are probably OK.  I notice that both these are for irrigation.  Any information would be welcome.  I'd really rather not use the poly.

I have an elbow with a ball valve at the end at the bottom of my first flush pipe.  Much much easier than my first try, which was a threaded end.

Asphalt fence paint seems to be staying on the poly tank, by the way.  (Henry's 107 asphalt emulsion would probably do the same, but this was open.)


glenn kangiser

Now you tell me -- many old houses use galvanized pipe and most wells that don't use PVC use galvanized pipe (the majority).  Seems there is always one more thing that is going to get us. :-/
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

Dustin

I read on another web page that you can use galvanived steel for drinking water, but you need to have the interior treated with a coating to make it safe. (NSF Approved Polyurethane Elastomeric Coating on tank wall- Ceramic bitumastic butylene emulsion)
What's wrong with a poly tank? Obviously you would want it to be either buried or protected from the sun if above ground, but I don't see anything wrong with them. Perhaps you have some experience I haven't heard about.
I have seen some houses in Tucson with galvanized steel tanks for rainwater harvesting and I thought they looked pretty cool, but they didn't seem to be very large and if I were going to use them for drinking water I would like to store more.
I will have to buy a tank anyways for my well setup, but I'm not sure what kind I will buy (though I am leaning towards a buried poly), and probably also do some rainwater harvesting setup, but I'm not sure if I would put both water sources into one tank or two.

Amanda_931

a) difference between living in an environment (fish do not do well with an excess of zinc in a galvanized tank) and passing through one.  Roofs, and therefore presumably pipes, are OK.  Zinc, especially zinc oxide, is relatively non-poisonous, which the person who mentioned this on another list didn't seem to realize.
 
I understand that the point of galvanizing metal is so the zinc can oxidize slowly, protecting the steel which would rust much faster.

b) What's right with poly tanks?  Cheap, especially in the smaller sizes (1500 gallons on down)  Even above-ground they can work, see them all the time in farmer's yards.  I've tarped one, fixing to put asphalt paint on both down at the barn.  I use that water for laundry plant watering and sometimes showers.

Wrong with them?  I've seen both semi-respectable and totally flaky people think that they can leach suff you probably wouldn't care to have in any kind of quantity in your body.  Estrogen-like substances that can be stored in fat, for instance.  Apparently polycarbonate--until recently the gold standard for safe--is beginning to be thought of as worse than polyethylene.

c) Buried tanks shouldn't get empty.  So they work fine for septic tanks.  But I have vivid memories of a lot of rain from the tail end of a hurricane floating our (steel) fuel oil tank when I was a child.   It would have been fine if we'd already filled it for the winter.

d) Now everything's awful, what do we do?  I'm thinking that those semi-buried site-built Brazilian tanks are the way to go.  Concrete has its own problems (the big one is overuse), and current practice has it sealed as well, although Art Ludwig (God of greywater systems) thinks that you can get by without sealing it if you can tolerate an occasional seep.  He also has directions in his book on water storage for a very very cute ferro-cement Thai Jar of somewhere around 3000 gallons.  (first you take canvas and sew up a form....)



Dustin

Have you heard about this coating they put on the inside of galvanized steel tanks I saw? Is that safe? Or are we just stuck with concrete as being "safe"?

I can see why buried "floating tanks" would be an issue, though in a well situation I think I would keep my tanks pretty full, since I would set the pump on a float switch to work when the tanks has been drawn off. Rainwater harvesting, if the tank is seperate for my well setup, would be a concern.
Hmm.


Amanda_931

No clue on coatings as safe, either the one for concrete or the one for the galvanized.  

It would partly depend on how long the coatings were expected to last--if there's a recommendation that you re-coat every five years or so, I take it as an indication that there might be a problem.

Depending of course on what the coating is made of, how it's manufactured, etc.

(having a sacrificial coating over a sacrificial coating sounds a bit weird, but it might be fine.)

Daddymem

Floating is relatively easy to overcome.  Bouyancy calculations are a must for all tanks buried where groundwater could be a concern.  A concrete pad or attachment to an anti-floatation ring will take care of it.    Simply take the volume that the tank takes up and multiply by 62.4 to get the bouyancy force.  Now take the weight of the tank (some take the weight of the soil on top of the tank too) assuming it is empty.  If the bouyancy is more than the weight, you need to add some weight to hold it down, simply figure out how much weight and add a concrete pad that weighs that much.
Où sont passées toutes nos nuits de rêve?
Aide-moi à les retrouver.
" I'm an engineer Cap'n, not a miracle worker"

http://littlehouseonthesandpit.wordpress.com/

Amanda_931

Glad to know it can be done.

And we probably ought to run the figures even with a semi-buried tank.


Daddymem

To be safe, I always assume full submergence.  And now that you know the trick...you can build a concrete canoe!
Où sont passées toutes nos nuits de rêve?
Aide-moi à les retrouver.
" I'm an engineer Cap'n, not a miracle worker"

http://littlehouseonthesandpit.wordpress.com/

glenn kangiser

Or a concrete ship - I think my dad mentioned these once.



Concrete ships of WWII
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

Amanda_931

The original rainwater harvesting site (not any of the rest of the site, IIRC) from that guy who used to live in Portland is back up.  We looked for a while for it back a bit.

There are a lot of probably interesting links here--including propaganda for a three-volume set of books on the subject:
http://www.harvestingrainwater.com/resources/

[highlight]here is what I was looking for--[/highlight]after an absence from the net.  The story, with a picture or two, of an inexpensive not-his-whole-water supply, permitted system in Portland.

http://www.harvestingwater.com/rainwatr.htm

Leo

there was a book by Jay Benford Naval architech called "ferro cement boatbuilding"A bad reputation for ferro cement boatbuilding was in large part from the use of chicken wire ,"but when welded rabbit cage wire was used and the curing process of keeping the hull wet for 30days if my memory serves me right. a very strong hull  was possible.there were many boats built from benfords plans many in the Seattle area.ferro cement properly done has much to offer including freedom of shape.  it was a pleasure seeing the  concrete ships at kipoteke as many hours of fun was had fishng from them in my younger years and I was always amazed how well they have stood up under time and elements.

glenn-k

#13
Here are plans and instruction for a partially underground rainwater tank.

http://www.eng.warwick.ac.uk/DTU/pubs/tr/rwh/rwhtr01/tr01.html




I want a ladder like that. :)



Amanda_931

You use to see ladders like the one on the left on every construction site in the area.  Not infrequently they were twisted and/or broken.

I need to talk to the guy in the next county over who has been building what my source claims is easy water tanks out of 4" concrete blocks--apparently he pours and seals a slab. surrounds (or puts on top??) a circle of 4" block.  Runs a plastic (??) strap around it to minimize the gaps, which he then fills--with something on the order of fiber-reinforced concrete/mortar.  Repeat until it's as tall as you want it.  Then fabricate a top somehow.

I'm about to decide that I probably only need a pair of 1500 gallon tanks for both house and shop.


John_C

Rainwater was the sole water suppy for the house I built in the FL Keys in 1983-4.   I had an above ground cistern that measured 14'x27'x approx 7'tall. It had two equal chamber of just under 7,000 gallons each  It was built of concrete blocks. We used what were then called knockout blocks.  They had scored sections in the webs betwen the open spaces that the block layer removed (knocked-out) when laying the blocks.  This left a ~4"x~4" void horizontally in each course of blocks.  We laid #3 rebar in these voids and it was tied to #4 bar which was placed vertically every 2'.  After the cover was formed the whole mess was filled with concrete, using pump mix and a vibrator to get the stuff down the vertical cavities and to encourage it to flow through the horizontal voids of the knockout blocks. After it had cured the entire inside was coated with a product called Thorough-Seal (sp?).  

The house had a poured concrete roof which was also "painted" with Thorough-Seal.  3" PVC pipe brought the water from the roof of the stilt house down to the cistern.  The house had a fair sized porch out back and steps down to the top of the cistern.  There was a railing around the cistern and we kept the bbq grill out there. About 7 yrs. after I built it my tennant put a hot tub on top of the cistern and steps down to the back yard.

There was a LOT of steel in the cistern slab, walls and top. I don't own that house anymore but I probably have the steel spec around here somewhere. The steel had to have an engineer's stamp. The only time I or my tennant ran out of water in 20 years was when a pipe broke and the pump just kept going until it was empty.  Had my tennant been more careful minding the valves it would only have emptied one chamber.  

As always your mileage may vary.  :)


glenn-k

Great info, John C.  I was reading that there are sealers readily available that you add to the concrete to waterproof it.  I haven't found them but have found some reference to crystallizing sealers.   I'm interested in sealers for potable water.  

Don't know if I'll ever do anything about a tank but always interested.  

I got a used 1300 gallon black plastic one the other day for $130.00 and already have 2600 gallons for the well pump.

John_C

Here is a link.  It's Thoroseal and I did use the additive they talk about here Acryl 60
http://www.elgene.com/ma.html