Sealed catchment container

[Palanakonu]

randomq: I was in a rental for a year with a "Doughboy" catchment... not much of a fan of those (just my personal opinion). Don't think I'd even give a shot to trying something like a department store popup pool like that.

[Seeb]

quote:

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Originally posted by kalakoa

bigger tanks have more engineering issues

Say more about how big "bigger" is...?

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Taller more pressure on walls, wider more wave when ground shakes. No magic number

[Rob Tucker]

In simple engineering terms exceeding 6 feet tall in retaining water or earth weight is where it gets more expensive.

[Palanakonu]

Seeb / Rob: Are you sayng that those 4000gal tanks might be problematic?
I plan on having this right next to our little house (on post & beam) and would hate to think that a shaker would cause the issues like I've read about in Southpoint in years past.

[kalakoa]

Taller more pressure on walls, wider more wave

those 4000gal tanks might be problematic?

I'm sure there are formulae to determine the danger of it falling over given an earthquake of magnitude X, but I don't have enough math for that.

My instinct says the aspect ratio is important, and the dimensions of anything over 2500 gallons look ... potentially dangerous ...

[Seeb]

Somewhere there is a bunch of photos from the quake in the 70s of catchment that came apart or moved.they were mostly wood one but it gives you an idea.

Ferocement / gunite can be designed to deal with these issues. Poly tanks can be too, just someone has got to do the math.

[MarkP]

Just off the top of my head I would say that the corrugated steel catchment tanks are fairly bullet proof compared to a $200 swimming pool. Like an order of magnitude better. Of course you pay for it. I bought a 10,000 gallon tank that is 15' in diameter and 7' tall, with no cover, for just under $3,000. I have stretchy shade cloth over the top. I'm satisfied with the set-up although if I had more money I would have gone with a ferrocement tank for bulk storage and a poly tank for the cleanest water just prior to drinking. I can believe that the ferrocement tank with an integral cover would withstand a pretty good earthquake. I also have a fair amount of confidence in the poly tanks.

[terracore]

"They make roofs for regular catchment tanks. "

The guy at Island Catchment told me the "pre made" variety are made by a different company than who supplies most of the tanks (they don't fit). Fortunately, custom jobs are about the same price, which unfortunately, is roughly the same price as the tank.

Also, if its an existing tank, it has to be fortified in order to accept a solid roof.

[Palanakonu]

Got a rough quote for two different catchment sizes installed by a local company.
Figured I'll post the information here in case anyone needs/wants it.

Catchment cost:

10,000 gallon - $4,550
6,300 gallon - $3,900

This did not include the cost of sand, gravel, or any ground work.

Thought about copying the entire itemized quotes in here but felt that a little bad form, not know how the company would feel about that.

EDIT: This is for the galvanized catchments, and not for the poly tanks that I started this thread in reference.
Thanks for pointing that out MarkP.

[MarkP]

Those quotes must be for galvanized steel tanks. Ferrocement would be much more expensive and poly tanks don't come that big, plus a 4,000 gallon poly tank costs $4,000 so 2 or 3 of them would far exceed those quotes.