PDA

View Full Version : Harvesting rainwater experts needed


Remote Pigtails
03-02-2007, 10:18 PM
I have a very long time customer who is going to build their dream home in Dallas. This is going to be the ultimate environment friendly home. Anyway they called me for expertise on putting a cistern under their garage to harvest rainwater to use in the automatic sprinkler system. Since I will end up taking care of this system I need to know everything about this. Two requests: Can anybody steer me to a site that explains this and if you are or know a local contractor who has expertise in this area please contact me.
:help:

Wet_Boots
03-02-2007, 10:32 PM
Not an option. Praise their interest, but move on. Only if they were considering genuine desert landscaping could something like a cistern possibly make sense. Otherwise, the water needs will exceed any storage capacity of any cistern. If they have room to construct a reservoir, then look into using stored water. Otherwise, forget it.

Mad Estonian
03-03-2007, 02:21 AM
I like this site, there's some good info if you poke around. I have a few of their books, haven't tried putting any of into practice yet. Some residents on the smaller islands around here are having to harvest rainwater for domestic use, but they certainly aren't watering any lawns with it. http://www.oasisdesign.net/index.htm

PurpHaze
03-03-2007, 09:34 AM
And there has to be a difference in annual rainfall between BC and Dallas. :)

Remote Pigtails
03-03-2007, 09:36 AM
Not an option. Praise their interest, but move on. Only if they were considering genuine desert landscaping could something like a cistern possibly make sense. Otherwise, the water needs will exceed any storage capacity of any cistern. If they have room to construct a reservoir, then look into using stored water. Otherwise, forget it.

I'm inclined to agree with you. When I drive in the country and see holding tanks, ponds, etc I just can't fathom having enough rainfall to maintain a traditional dallas landscape. I'm guessing this isn't going to be traditional. In talking to them I suspect they were told of other people doing this. They will still use city water but try to minimize their need for it. She said there was a method that the city water would refill the tank when it dropped to low. (I'm imagining this giant toilet tank structure) We tend to get our rain here in large bunches or none at all. Great for filling large lakes fast but not for maintaining constant levels. Here is the main problem I see: screening out the leaves and dirt. Somehow that tank is going to need to be cleaned on occasion. With a landscape plan (they are working with a L. A. now) a fairly rough estimate of their water needs can be determined. All food for thought. I liked that Oasis web site. need to study it further. If I was smart (NOT!) I'd let this go but I'm a kindred spirit of this type of thinking.

Remote Pigtails
03-03-2007, 09:42 AM
And there has to be a difference in annual rainfall between BC and Dallas. :)

We average about 35 inches a year. It just comes all at once or none at all. The reason we have so many foundation problems here is we go from saturation extremes to dry extremes which is a problem in expansive clay soils. This same problem makes us less than ideal for desert landscaping. Dallas is a very difficult gardening climate. Right smack in the middle of two zones.

Remote Pigtails
03-03-2007, 09:59 AM
This has the potential to become a kludge.

PurpHaze
03-03-2007, 10:25 AM
This has the potential to become a kludge.

I really like that word. Can't wait to use it on a couple of my work orders. :laugh:

PurpHaze
03-03-2007, 10:29 AM
We average about 35 inches a year. It just comes all at once or none at all.

Therein lies the problem. I can't see a cistern as anything more than supplemental watering of landscapes in your area. And if it needs a recharge source such as domestic water to make it through drier spells then where is the gain?

Dirty Water
03-03-2007, 11:51 AM
It takes 27152 gallons to put one inch on one acre.

Here is my suggested storage tank:

http://www.sanjuan.k12.ut.us/sjsample/TUNNEL/WEBTUN/13tank.jpg

Hank Reardon
03-03-2007, 11:51 AM
And there has to be a difference in annual rainfall between BC and Dallas. :)

Here in the Puget Sound area, we actually average only 36" annually. Most of it falls from October through May/June with hardly anything in the summer months. We rarely get those deluges like DFW gets.

Wet_Boots
03-03-2007, 11:56 AM
If you owned an old missile-silo site, then you'd have a cistern to reckon with.

Remote Pigtails
03-03-2007, 01:21 PM
It takes 27152 gallons to put one inch on one acre.

Here is my suggested storage tank:

http://www.sanjuan.k12.ut.us/sjsample/TUNNEL/WEBTUN/13tank.jpg

This is really the beginning of the solution. It is basically going to become a math problem. I'm going to do a little more research. Get the landscape area. Determine how much of it will be individual plant watering vs space watering. They may have decided not to have a lawn. After I warm up on a really tough sudoku puzzle I'll put a pencil to it and publish my results for grading.

justgeorge
03-03-2007, 01:21 PM
This same question comes up now and then. Bottom line is, if it rains enough to keep the cistern filled and refilled, then you wouldn't need to irrigate in the first place.

George

Mad Estonian
03-03-2007, 01:23 PM
And there has to be a difference in annual rainfall between BC and Dallas.

I'm in Sooke, an hour west of Victoria, "The Garden City." They were smart enough to have the city's reservoir out here. We've had over 68" since Sept. 1, which is 1.5X average. Victoria only gets about half of that, due to what they call the "rainshadow effect" of the Olympic Mountains.

I looked up "kludge" on Wikipedia. You can also call it a "bodge," or my favourite, a "Macgyverism."

RP- I sent you a private message with a local guy who does this sort of thing's e-mail. Look forward to hearing how it all goes. I think you'll need to get in touch with your inner Macgyver for this one.

Remote Pigtails
03-03-2007, 01:37 PM
This same question comes up now and then. Bottom line is, if it rains enough to keep the cistern filled and refilled, then you wouldn't need to irrigate in the first place.

George

Very good point. Too obvious to see. I guess the rebuttal argument would be that you collect water during rainy times that is held for use during dry times. Assuming that being stored underground in a tank prevents evaporation. Nonetheless I calculated my own water use at around 300,000 gpy. That is a mighty big tank.

Remote Pigtails
03-03-2007, 01:39 PM
And there has to be a difference in annual rainfall between BC and Dallas.

I'm in Sooke, an hour west of Victoria, "The Garden City." They were smart enough to have the city's reservoir out here. We've had over 68" since Sept. 1, which is 1.5X average. Victoria only gets about half of that, due to what they call the "rainshadow effect" of the Olympic Mountains.

I looked up "kludge" on Wikipedia. You can also call it a "bodge," or my favourite, a "Macgyverism."

RP- I sent you a private message with a local guy who does this sort of thing's e-mail. Look forward to hearing how it all goes. I think you'll need to get in touch with your inner Macgyver for this one.

I don't know if i want to give up my inner hillbilly.

Mad Estonian
03-03-2007, 01:53 PM
I don't know if i want to give up my inner hillbilly

Well, you could be the hillbilly Macgyver. Banjo strings are almost as versatile as duct tape.

bicmudpuppy
03-03-2007, 04:48 PM
If you give up the concept of true functionality and give in to the tree hugger/we want to make a difference mentality, this type of system can be constructed. Best case scenario, your going to get back half the storage of the cistern maybe 1/3 of the times you water. I had one of these to maintain (we didn't install it, but we made if function) in Lawrence, KS about 7 years ago. Under the basement of the house was the equivalent of another basement being used as a cistern. Lawrence is the liberal tree hugger capital of the mid-west. I never figured the exact volume of the cistern, but we could get two waterings from it w/o using city water. 6-spray zones @9-10gpm, and four bed zones @ 10-12gpm. Zones could run about 15 min each two - three times per week and the city water wasn't needed except in late summer drought periods. The pump and pressure tank in the basement was set to produce more pressure than the city provided with an RP on the city tap. If the well turned off because the low level switch came on, then the city water took over. If a broken head increased flow, the city water would run when the pressure dropped low enough to allow flow from the city poc. My understanding was the cistern was 8'+ deep and the house footprint would have been around 1200'sq. The lawn and beds were postage stamp size after subtracting house, garage, walks, etc.
but if there really was over 9K cubic feet of water, then the pool was adequate for a lot of water savings.

Remote Pigtails
03-03-2007, 05:15 PM
You've got these folks pegged. But you are giving me some of the answers I'm looking for. Now I just need to edit your paragraph so they don't see all the liberal/treehugger comments.

Wet_Boots
03-03-2007, 06:09 PM
Cisterns and stored water nowadays may have to be made mosquito-proof. Public health, in the era of West Nile, and other nastiness, is wayyyy more important than water consumption reductions.

Remote Pigtails
03-04-2007, 10:49 AM
Cisterns and stored water nowadays may have to be made mosquito-proof. Public health, in the era of West Nile, and other nastiness, is wayyyy more important than water consumption reductions.

having had a severe battle with WN virus I take this seriously as well. From my studies of mosquitoes I don't know if it possible to truly eliminate them without doing major damage to the eco-system. They love to live in St. Augustine grass, peat moss beds, and other areas that require constant moisture. They have a range of a mile and a half. I think one of the biggest sources of skeeter habitat are these drains run with those popup outlets. Thereby the drain pipes never empty. My guess is that in tracking WNV across the US the population eventually all get WNV and it no longer becomes an issue. You only discover you have it when you become deathly ill or die and then they check you. For most people it is a mild headache at worse.