Rainwater Harvesting

Redthistle(8)May 10, 2008

Hi All,

I looked through some old posts on this forum about rainwater harvesting, but would like more information if anyone has some to supply.

I have a huge roof with gutters that, while not perfect, certainly collects lots of water when it rains. I also have several very large garden beds I'd like to water.

I already know I will buy four 75-gallon water barrels from my city (one used for grey water collection), but I also want to install a rainwater tank and I have (at most) about $1,500-$1,800 to spend on it. Obviously, I want the biggest bang for the buck: durability, easy of maintenance, etc. No pump. I obtained one estimate from a company who wanted $5,600. for installation/set-up. This was more than I could afford. However, I have a friend who is a building contractor, and he's willing to help me put one in for considerably less.

Has anyone here installed their own tank and if so can you give me pointers about this? Pros/Cons of plastic versus metal with a liner, placement of the tank, pad for the tank, cleaning the tank, etc.


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Belgianpup(Wa/Zone 7b)

There are some good books on the subject:
Rainwater Harvesting for Drylands (Vol. 1): Guiding Principles to Welcome Rain into Your Life And Landscape by Brad Lancaster

Water Storage: Tanks, Cisterns, Aquifers, and Ponds for Domestic Supply, Fire and Emergency Use--Includes How to Make Ferrocement Water Tanks by Art Ludwig (the same guy who wrote the Greywater Oasis book)

I think it was in the first book above where the author suggested the cheapest method, a large plastic tank (5,000 gals???) (specific plastic, I don't remember what it was), but you wrap it with chicken wire, then apply a coat of concrete over it (maybe just an inch thick). The concrete shades the plastic and keeps the water cooler, and it protects the plastic tank for the #1 plastic-tank-killer, UV rays of the sun.


    Bookmark   May 11, 2008 at 2:02AM
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Thanks, Sue. I didn't see your post till today. Any advice is appreciated. I'll look into the books.--Maybe I can find them on Amazon.

    Bookmark   May 13, 2008 at 12:19AM
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There is a discussion group dedicated to rainwaterharvesting on another network that might be of interest. GW will not allow the link.

    Bookmark   May 14, 2008 at 12:51PM
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Thanks, gweirdo. I'll do a Google Search and see if I can find it.

    Bookmark   May 14, 2008 at 9:41PM
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gardenlen(s/e qld aust)


just dropped in, have you rung around and gotten prices from the tank manufacturers for the price of tanks, this way you cut out the unneccessary middle man. you prepare a site for the tank and if they operate like over here they will site the tank where you want it on delivery, the only condition there must be access that suits them.

would suggest a poly tank. over here we can get a 25k litre (app' 5k im[/gal) tank for around $2600AUD, they fit the flow valve tap for you and as i said site the tank for you, the rest is as easy as DYI your ever likely to do, run a downpipe to the tank and the over flow from the tank back to the storm water out pipe too easy, no need for glueing in most cases as the poly pipe is a tight fit and rainwater isn't under high pressure so we use self tapping screws with falt heads to hold it all together, one screw at each join is heaps.

no need to go overboard on site preperation for a poly tank, basically a soft sand bed for it to settle into and make sure it is level, you can get the dimension of the tank from the maker, over here you can get squat tanks (they are shorter but wider), or tall tanks depending on you needs.

25k liter is a good alround size to have plenty of water storage for those longer dry periods, you should find that you get more capacity for you dollar the bigger the tank so a 15k liter (3k imp/g) tank won't be terribly much cheaper that the bigger one.

if access is difficult just get a couple of mates around and roll it to the site then stand it up a bit of effort involved that way. with us the siting of a tank is one of the criteria when we buy a house.

if you have lots of trees and leaves in the gutters there are leaf traps that can be fitted into the downpipe easily and also would suggest first flush diverters we use the simplest cheapest system traps the first 7 litres of water, which we later harvest and use. our tank supplies our whole of house needs.

oh! don't store grey water use it as fresh as it comes, and we ahve a very well recieved laundry/handwash/general purpose cleaner gel, recipe on our remedies page.


Here is a link that might be useful: len's garden page

    Bookmark   May 17, 2008 at 2:59PM
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gjcore(zone 5 Aurora Co)

I've been thinking a bit about rainwater harvesting lately. Instead of having tanks, barrels, pumps, and all sorts of hardware maybe a simpler system of using your garden soil as the reservoir would be simpler. Connect your household downspouts to a system of pvc pipes underneath your garden with small drainage holes drilled into them. Sort of a t-shaped network, Of course one would need to account for gravity and it would work best for new garden plots that you aren't planning on tilling or gardens with primarily annual plantings. Just my 2 cents.

    Bookmark   March 23, 2009 at 10:37PM
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Belgianpup(Wa/Zone 7b)

You can also use that technique for using greywater for ornamentals. See Art Ludwig's "The NEW Create an Oasis with Grey Water" book. The new version has the branched drain system in it, the old one doesn't.


    Bookmark   March 24, 2009 at 3:23PM
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gardenlen(s/e qld aust)

using the garden soil as a reservoir is a good idea only thing is rain comes in a rush most times not in a trickle, so you would need something like an expansion chamber to take the sudden onrush of water then let it slowly seep into the soil (a tank comes to mind), so if you had a week of solid rain there might be issues otherwise.

by far and away the best harvesting method is substantial sized rainwater tanks, we are all but stand alone with our tank having turned off the city water about 2 years or so ago.

the thing to think of when running grey water through a system like a drip system is that it would need some sort of filtering to filter out lint and hair etc.,. and then you would need access to the drippers whatever so you could clean them when they block also. all means some sort of maintenance.


Here is a link that might be useful: lens garden page

    Bookmark   March 25, 2009 at 2:31PM
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I suppose you are wanting a tank of some kind because an open pond is not feasible? Ponds can store a lot of water for irrigation. It just depends on your land if building a pond is cheaper or not.

    Bookmark   March 31, 2009 at 8:10AM
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coffeehaus(7a Central VA)

We are in the midst of building a house and including a cistern that our GC is engineering. Using 1700 gal. plastic tanks, ganged together and buried with a pump.
From Water

While this is still a work in progress (no gutters, yet, for one thing), we will eventually post our project on SolarGary's website...see below. He posts on the Renewable Energy forum on the HomeSite side of GW. Maybe his links will give you some ideas.

Here is a link that might be useful: SolarGary's website

    Bookmark   April 8, 2009 at 7:34AM
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gardenlen(s/e qld aust)

looks like it could be a relatively expensive way of collecting rainwater especially on the property shown those 3 tanks will hold roughtly 6k/litres of water total, and the home had heaps of room for an above ground tank of 25-30+k/l tank which wuld be the more economical way to do it.

put tanks underground where space is very limited is a good idea. over here roughly people are paying app' $1kAUD for 4.5k/l tanks when a 25k/l tank comes in at app' $3kAUD, the 24k/l unit is more sustainable.


Here is a link that might be useful: lens garden page

    Bookmark   April 9, 2009 at 2:39PM
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coffeehaus(7a Central VA)

Redthistle...DH has found many informtive videos on YouTube. Try searching something like, "Rainwater collection".
Gardenlen...you are correct, this is relatively expensive, but we wanted to avoid solar degradation of the plastic and algae growth, and DH has a BIG garden that he wants to water without fear of running our well dry. We are in central Virginia, and the last few summers have been brutal with regard to drought. Projections regarding future trends in rainfall here are not encouraging. Also, since we are new construction on this house, it made sense economically to bundle this with the other excavation. It's not for everyone!

    Bookmark   April 9, 2009 at 3:45PM
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If your are looking for additional solid information on the pros and cons of metal vs. plastic tanks check out http://www.waterharvestonline.com
This is a relatively new site devoted solely to water harvesting. There are some people that post there who really know their stuff, it's probably worth dropping your post there too.

Here is a link that might be useful: Water Harvest Online

    Bookmark   June 17, 2009 at 7:13PM
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Steel and polyethylene are the most common materials for rain water tanks found in Australia. Other materials include fibreglass, concrete and PVC bladder tanks.
Each material has its strengths and weaknesses, but I believe the steel tank has the best features of all rain water tanks currently available. For more information please check out the link below.

Here is a link that might be useful: Why Choose a Steel Rainwater Tank

    Bookmark   October 30, 2013 at 6:53PM
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