Where can I find a large storage tank for a large scale rain catchment system? What type of tank if recommended?, 11°

The Homestead will be putting in a large scale rain catchment system once we have our new roof (lots of leaks) on this summer. Ideally, I would be interested in a 1.5-2 story cylindrical holding tank to be placed outside near the house. I can't seem to find anything on Craig's list or the Free-cycling circuit...any suggestions would be a big help!

11 replies

Matthew W. 536°

Hi Jayne - our water supply is from rainwater only too... it's relatively common in rural areas of New Zealand. Our tank is just from a standard 'farm depot' type store - and more likely to be stocked in farming-type areas. Hope this helps!

Written in July 2008

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Matthew W. 536°

Also, so you don't have to go through the 'learning experience' that we did, I'd really recommend putting some a mesh cover over the gutters around your house, as leaves from nearby trees will block things up very quickly - and spending an afternoon every 2 weeks getting old leaves out of the gutter in order to get enough rainwater for a shower isn't much fun - believe me!! :)

Written in July 2008

Hey Matthew, Thanks answering my question. It does help. I also appreciate the advice. We will be fixing up our roof before winter and hope to get a rain catchment system going next summer depending on funds, time, etc. As you probably know, you need to start your research early so you have some idea of what your doing...:) Thanks!

Written in July 2008

Jayne: IMHO the best water tank is a concrete one, built on-site for the purpose. (the plastic ones not only use fossil-fuels in production, but leach PHPs and also have a tendency to burst.) best place to site it is under a deck - or indeed, as an integral part of a deck - or "buried" into a slope in the garden (then you can use the top for a BBQ/etc area). either way you dont take up valuable space and its visually unobstrusive.

as for cutting out gutter waste, a simple mesh filter, inline in the downpipe (and available as a pre-built section in any decent plumbing store), will divert all leaves etc from the intake.

capacity is the key; depending on average rainfall, and whether you have a long dry summer, allow around 1800 gallons capacity per person, perhaps as much as 2500 if it gets really dry for, say, 4-5 months. so a 6000 gal tank in a temperate climate will do for a 3-4 person household.

any questions, happy to advise.

Written in July 2008

oh, ps: it also depends on what applicances you have; if you have eg a dishwasher, you need to add 2-3000 gals to your capacity! (much greener to wash by hand.)

Written in July 2008

one more thing: consider whether you need pressurised water or not. if you do (eg, if you shower rather than bath - or to accommodate mosty modern washing machines) then buy a pressure pump to take the water into the house. if you dont, then use a simpler pump to (re)fill a header tank on the roof; gravity feed does the rest.

Written in July 2008

Charles M. 110°

If this is your only water source, then sizing is a big issue. What is the longest period that you will not get proper rain for? Double that. That's the minimum amount of water you need to store. Huge tanks will need to be placed on or in the ground and will need a pump to pressurise it. It would make sense to talk to a local farmer coop etc. Tank water storage is nothing new and local information is essential.

All our water comes from a 2000l (500USG) tank on a stand that is approximately 5ft higher than the ceiling. That is all the pressure we need to drive a shower, washing machine etc.

Written in July 2008

Great information from experienced environmentalists. The climate here is temperate. Our summers last from May through August. However, we have about 5-6 months of winter with a lot of snow. Any ideas on how to catch it? Thanks! This is a big help.

Written in July 2008

C Robb W. 444°

A question for Bruce,
Concrete is one of the most fossil fuel intensive products on the planet. Does a concrete tank really use less than a plastic one? I'd be willing to forego the plastic for other reasons, the leachate being the main one, but wonder if a limecrete tank is possible? In Bermuda everyone collects rainwater and traditionally the limestone tanks were rendered with lime wash which served to purify the water as well as storing it. Now everyone uses concrete and purifies with chemicals, typically chlorine. Limecrete absorbs CO2 and is much less energy intensive than concrete but I'm unsure about it's structural properties. Have you heard of using it in this way?

Written in August 2008

good point Robb! its the cement that is the problem re CO2, and yes, lime can replace cement in the mix (with/plus sand stones water of course) though i am not personally familiar with this practice. you'd need to look up ratios etc and whether anything else is needed to help the lime do its thing.

yuck, chlorine! no way! if you're in open country and not near a major industry, you shouldn't (!) need to purify rainwater, but if you do, buy an inline filter that uses bonding techniques to take any nasties out. for problems such as mosquitos (which like to breed in water tanks) pour a little meths into the tank; it sits on top and stops the mossies breeding. (and because the intake is down low, doesn't get in the supply).

Written in August 2008

Charles M. 110°

If you're getting picky about the CO2 usage of making cement, then be aware that lime also uses heat. As a more practical consideration think of this as an investment: using a small amount to make savings elsewhere.

With lime you need the tank to age for a long time before usage. Much of lime's integrity comes from mineralisation from absorbed CO2. For that to work properly the lime has to have access to the air for a long time (many months) and actually continues "forever". That won't happen if the lime is underwater.

Chlorine is a baddy and is not a good idea. If you have industrial contaminants then chlorine is not going to fix that. Chlorine will only kill of biological hazards and there are more gentle ways to do that.

UV sterilisation will kill bacteria etc but will not clean up chemical pollutants either. It needs electricity though.

Consider filtering. Doulton water filters have been doing chemical and biological filtering for ages (over a hundred years):http://doultonusa.com/HTML%20pages/technology.htm

If you are concerned about contamination then you should install a bypass that dumps the first few gallons of water thus washing the roof contaminants away. That should get rid on many industrial and biological contaminants.

Written in August 2008

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