Water Storage Tanks

[nanasohana]

I suppose I should wait till our new owner builder forum starts for this, but anyway, how large a tank, what kind, and how much did everyone pay for theirs, where did you get it?

[adias]

I had posted this on another thread, but it should be here...Probaby required reading for anyone getting a water catchment system...

Guidelines on Rainwater Catchment Systems for Hawaii.

http://www.ctahr.hawaii.edu/oc/freepubs/pdf/RM-12.pdf


Ajit

Edited by - adias on 11/17/2005 18:35:25

[HADave]

Hi Nancy, I believe someone else said "10,000 gals. was the min to cover insurance requirements." WaterWorks in Hilo gaurantees Best selection,Quality, and Price. Their phone number is 933-9111 They also sell pools if you know of a pool for sale you can use these formulas to determine gallons.

round; DIA x DIA x AVG DEPTH x 5.9 = gal oval; L.DIA x S.DIA x AVG DEPTH x 6.7= gal
RECT L x W x AVG DEPTH x 7.5 = gal

Also liners must be of food grade quality.
hope this helps

Dave

[wyatt]

Water works is who we purchased from. We went to 1 other and talked to 2 more on the phone.
They all seem to be reading pricing from the same list. Water works does offer a 5% discount if you purchase the full sytem. They were supposed to have a price increase Nov 15. Thats why we prepurchased our tank in advance. I don't know if this price increase is an industry wide issue or just from their supplier. Big Island Tanks has a larger filter canister than you can't get from water works. And my insurance agent told us we had to have 10,000 gal minimum for fire insurance.

Wyatt

[JohnS]

The free downloadable Texas rainwater harvesting manual (3rd ed.) is more refined and comprehensive than the recent Hawai'i guide:

http://www.twdb.state.tx.us/publications...inHarv.pdf

Their whole site is quite informative.

For more information on proper water storage systems and catchment systems:

"Water Storage: Tanks, Cisterns, Aquifers, And Ponds for Domestic Supply, Fire And Emergency Use..." by Art Ludwig
He also has the best info on graywater systems and an upcoming book on rainwater harvesting - see http://oasisdesign.net/ for more.

His above book draws on info from the more encyclopedic:

"Rainwater Catchment Systems for Domestic Supply," by Erik Nissen-Petersen & John Gould

At a minimum your system should have the following features:

Gutter screens and/or guttersnipes
First flush diverter
No standing water in delivery pipes
Truly closed, plumbed and sealed tank

I have seen almost no systems (aside from mine) with any of the above here. In fact I have yet to see even the simple improvements in the recent Hawai'i guidelines booklet implemented by catchment companies. Catchment here is fourth-world - most third-world aid projects described in Nissen-Petersen & Gould's book are better designed for water quality and safety.

I recommend against the usual open doughboy pool or corrugated tank with PVC liner. The only tanks I can truly recommend for a quality water system are truly closed and properly plumbed tanks made of HDPE (Hawai'i Chem-tainer) or ferrocment (Pacific Gunite, or DIY).

One design option to keep the cost down is to have a small, properly done tank for your household potable water which overflows into a larger, typical local design cheap non-potable tank for insurance/fire/outdoor/ag/laundry/etc. uses.

aloha,
John S.

[wyatt]

Hi John,
the four things you mention for at least were all brought up by tank sales people.
Well The screens by us.
I would assume the are installing that way if the inform their customers. Plus they send you home with a guide book that fills in all the gaps. book is free and availabe in ther office. It prob. is the same as the pdf link that adias supplied.

[JohnS]

Good to hear they are mentioning it.

In practice however I am not seeing it, so I would not assume you are going to get it as standard.
I live in HPP, there have been plenty plenty homes built here in the last couple years.
I have seen one, maybe two that have closed tanks on site.
All the dozens and dozens of other catchments I see going in have none of those four items. Granted I haven't gone up on ladders to look for gutter screens on strangers' houses... :-) ...and, I haven't seen any on a random selection of friends' homes, old or new.

The Hawai'i guide does not fill in all the gaps. They get the "no standing water in pipes" and the first flush diverter (though their design with a long horizontal run of pipe is not recommended). Can't recall if they mention gutter screens.
They don't mention the importance of closed tanks, and all that other protection before the tank is somewhat wasted if the tank is not sealed.

[wyatt]

I agree most probabily aren't up to standard. I don't know if it's people not being in formed or tryiny to simplify. I haven't read the guide
cover to cover. I did look into the sealed poly tanks. Pricey and size constrants. I will be installing my own tank. the dealers wanted $1,200. -$1,500. to set tank sub,sand, and put together. I will probably be design changing as I install. I feel confident I can do it and have good safe
water system. I worked at a 33 acre Aquaculture Closed System facility for 7yrs.
Installing tanks and filter systems was a common thing.

[wyatt]

When I was on Big island a couple of weeks ago
I read an article on dangerous slugs in water catchments. interesting reading.

http://www.hawaii-island.com/slug.htm

wyatt

[mella l]

Wyatt thank you for posting the link to Sammy the Slug article. Very thorough and necessary info and we will be mindful now of the real dangers and preventions of cachment system problems when we are ready to do one. Most catchment systems I have seen are screened off with vegetation and we will not be doing that. The six foot diameter of clearing and crushed lava to keep the pests away is very good. There will be other ways of hiding the tank if that is necessary. Thanks again for sharing this info. Mella L

mella l