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I presume you are talking about a "doughboy swimming pool" type of catchment tank. As pointed out in the CTAHR handbook on rainwater catchment*, a free booklet everyone who has a catchment system should own and read, a big problem with them is that they are vulnerable to collapse due to earthquakes. So, yes, placement relative to the house is important.
A friend was going to place one uphill from the house, basically at raingutter level, thinking this would be a great way to get some built in water pressure... until I showed him how a seismic event could cause waves that could knock the pool wall down and create a mini-tsunami that could take down his whole house. He hadn't thought of that. [xx(]
And in other news, I have a neighbor in Volcano who built a new house, fully permitted, by the book, and had a company install a corrugated steel water tank... which failed inspection because it was 1' too close to the house. No kidding, they had to take it apart and move it. [:0]
I'd at least check out that place in Shipman Park that manufactures the molded poly tanks. Sometimes they have B grade merch at reduced prices that is structurally sound but has visually flaws or needs cleanout before use.
*Free hardcopy booklet is available at County Extension offices, and pdf file is available free online:
http://www.ctahr.hawaii.edu/oc/freepubs/pdf/rm-12.pdf
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I have seen a number of backyard tsunamis
http://pacificgunite.com/earthquake.htm
If you can afford it, get a real tank that won't burst. No restrictions on distance to structure with concrete tanks because they don't break. Yes they're not cheap iinitially but in the long run they are the bargain because there is zero maintenance and they will outlive us all. We have helped many homeowners build their own ferrocement tanks to save on the cost.
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from what i understand about gravity systems, they need to be 10s to 100s of feet higher than the spigots to get any appreciable water pressure.
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quote:
Originally posted by bluesboy
from what i understand about gravity systems, they need to be 10s to 100s of feet higher than the spigots to get any appreciable water pressure.
The number you're looking for is: 0.42 psi per foot of elevation, so to get 30 psi the tank needs to be about 70' high, and you would want to oversize the plumbing to avoid losing all that pressure to friction.
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quote:
Originally posted by bluesboy
from what i understand about gravity systems, they need to be 10s to 100s of feet higher than the spigots to get any appreciable water pressure.
I didn't say his plan was well thought out... [:0]
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The place in shipman is called Chemtainer, they have various sizes and will give you a quote over the phone.
Mac nut
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I recently completed a 10' dia x 4' high 2,000 gallon tank made out of two galvanized steel cattle panels overlapped on the ends and fashioned into a ring. I set it on a gravel and sand foundation that sloped to a low spot in the center and lined it first with roofing paper to protect the liner from the metal and gravel. The liner is a 20' x 20' piece of black 6 mil contractor's plastic. I covered it with a $25 10' x 10' piece of shade cloth from Ace that is bungied to the sides and supported in the middle with a $10 30" Gold's Gym exercise ball from WalMart. It looks really nice and cost only about $300 for everything. I had to get more storage and it had to be cheap. I accomplished that. I don't know how long it will last. If I had a decent budget I would opt for a very large ferrocement tank and go in style. That would look out of place beside a rusty container though.
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The exercise ball idea seems brilliant, though I'm unsure it's material and your liner would qualify as "food grade" and stand up to sunlight and other aging complications. What are galvanized cattle panels? Are they like corrugated tank panels?
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The cattle panels are essentially fence panels of 1/4" galvanized steel rods running horizontally and vertically welded where they cross, forming rectangular openings. The tar paper and liner bulges out through each square slightly.
The liner will last a few years. I have hunks of that plastic that have been lying around in the sun that long without any protection. In this application the plastic is relatively protected. As for food grade issues, I frankly think the risk is overblown. I don't doubt that lead paint or solder is bad, but this ain't lead paint. As for the exercise ball, you've got a point. I opened it in the car and the stench of fresh plastic nearly knocked me out. For that matter I couldn't figure out where the smell of burning brakes was coming from as I installed the shade cloth until I looked down at the wadded fabric in my arms. Still, I doubt that there are any heavy metals in either and the contact with the water is very small.
Are vinyl gutters food grade? Also I painted the roof with latex paint. Then there's the solar panels on the roof... I use county water for drinking. I assume that the blue 5 gal water cubes are food grade as well as the clear 5 gal menehune water jugs. There is a lot we take for granted. I bought a hose that was supposed to be food grade, but I have drunk from hoses all my life that were not. For the majority of my life there was no such designation as food grade.
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Yup, it seems unlikely that all of the surfaces and substances used in the containers, cans, pipes, gutters, roofing, etc. we use have been thoroughly tested for toxicity and safety. Nor am I sure I would like these all to be tested on hapless animals in an effort to confirm their safety. Witness the coal-cleaning chemical spill on the mainland; seems the culprits have no clear understanding of the liquid's safety when it's accidentally introduced to municipal water for home use.
I shower in my catchment water, and would like to use it for cooking though (rice, tea, etc.), and so strive to minimize potential sources of toxic material contamination. I have heard that some use smaller dedicated stainless rain collection systems exclusively for kitchen/cooking use and drinking, an idea I'd like to pursue.
