# Why aren't water catchment tanks used in the desert southwest of the US? **URL:** \ **Category:** Factual Questions\ **Created:** [December 3, 2013, 2:30am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333 "2013-12-03T02:30:49Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mangosteen](https://avatars.discourse-cdn.com/v4/letter/m/6a8cbe/32.png) [@Mangosteen](https://boards.straightdope.com/u/Mangosteen)\ **Post date:** [December 3, 2013, 2:30am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/1 "2013-12-03T02:30:49Z")
Just outside my home on the Big Island of Hawaii, I have a 10,000 gallon catchment tank that takes care of all my family’s water needs from drinking to showering. The home is not connected to any city water line. Of course, there is a filtering system that cleans the water before it comes into the house. The area where I have the home ( 7 miles north of Hilo ) gets around 120 inches of rain a year so the tank is always full. The system works by capturing the rain that hits the roof. This water is sent to the tank via the gutters on the edge of the roof. (The tank itself has a cover to keep the critters, and their poop, out.) I know places like Phoenix only get a few inches of rain a year, but even if it rained just two or three inches over a short period of time this would translate into many gallons of valuable water that could be stored and used during the normal long dry spells. The tanks are not pretty nor are they small, but they can be installed at least partially under ground and surrounded by bushes. ---
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [December 3, 2013, 2:57am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/2 "2013-12-03T02:57:35Z")
If you live in Phoenix you have inexpensive city water so I don’t think there’s really a need, and if you live outside the city I don’t think it would ‘catch’ enough water to supply a family 100%… so other options are needed. I could see using it as a supplement, but then the cost wouldn’t justify the benefit. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [December 3, 2013, 3:02am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/3 "2013-12-03T03:02:43Z")
It’s illegal to collect rainwater in much of the southwest desert. In many places the territorial government made claim to the water rights on all land before it was settled, in others, there are strict rainwater regulations resulting from the Colorado River Compact. When they loosened rainwater regulations in Colorado a couple years ago, it was a big deal when some people were able to (legally) put barrels on their gutters. ---
**Author:** ![sevenwood](https://avatars.discourse-cdn.com/v4/letter/s/6de8d8/32.png) [@sevenwood](https://boards.straightdope.com/u/sevenwood)\ **Post date:** [December 3, 2013, 3:04am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/4 "2013-12-03T03:04:17Z")
According to [this site](http://average-rainfall.weatherdb.com/q/27/445/What-is-the-average-annual-rainfall-in-Phoenix-Arizona), Phoenix Arizona gets an annual average of 8.03 inches of precipitation. It would probably cost a Phoenix homeowner about as much as it would cost someone in your area to build a private water catchment system - for about 7 percent of the benefit. And as (I believe) that’s not enough rainfall to completely supply his house, he’d still have to be connected to the city water system. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [December 3, 2013, 3:10am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/5 "2013-12-03T03:10:50Z")
> [@Mangosteen](#): > > The system works by capturing the rain that hits the roof. This water is sent to the tank via the gutters on the edge of the roof. (The tank itself has a cover to keep the critters, and their poop, out.) So your critters are so circumspect as to never poop on the roof? Just what kind of filtration system do you have to make that roof runoff potable? A simple screen wouldn’t work, and a reverse osmosis system is expensive and slow. Ultraviolet purification? ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [December 3, 2013, 3:12am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/6 "2013-12-03T03:12:20Z")
In some places in the USA, you do not legally own the rainwater that falls on your property. See [ul] [li][http://www.popularmechanics.com/science/environment/water/4314447[/li][li]http://www.huffingtonpost.com/2012/08/16/gary-harrington-oregon-water-rainwater\_n\_1784378.html[/li][/ul]](http://www.popularmechanics.com/science/environment/water/4314447%5B/li%5D%5Bli%5Dhttp://www.huffingtonpost.com/2012/08/16/gary-harrington-oregon-water-rainwater_n_1784378.html%5B/li%5D%5B/ul%5D) ---
**Author:** ![sisu](https://avatars.discourse-cdn.com/v4/letter/s/df705f/32.png) [@sisu](https://boards.straightdope.com/u/sisu)\ **Post date:** [December 3, 2013, 3:15am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/7 "2013-12-03T03:15:45Z")
In Australia (I live int he suburbs) it is now pretty common for people to have rain water tanks using the water for flushing toilets, watering gardens etc. We had a major drought a few years ago and these became standard issue if you wanted a lawn due to water restrictions. ---
**Author:** ![Mangosteen](https://avatars.discourse-cdn.com/v4/letter/m/6a8cbe/32.png) [@Mangosteen](https://boards.straightdope.com/u/Mangosteen)\ **Post date:** [December 3, 2013, 3:32am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/8 "2013-12-03T03:32:23Z")
> [@Musicat](#): > > So your critters are so circumspect as to never poop on the roof? > > Just what kind of filtration system do you have to make that roof runoff potable? A simple screen wouldn’t work, and a reverse osmosis system is expensive and slow. Ultraviolet purification? I use a Sawyer system, many people use UV. [http://www.sawyer.com/tech-water.html](http://www.sawyer.com/tech-water.html) ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [December 3, 2013, 5:47am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/9 "2013-12-03T05:47:19Z")
> [@sisu](#): > > In Australia it is now pretty common for people to have rain water tanks using the water for flushing toilets, watering gardens etc. . How does the plumbing work? Do you have to turn a valve to open and close the rainwater tank? And what supplies the pressure for the rainwater tank–is it located on the roof? Or is there a pump? You need two separate sets of pipes in the house: one set connected to the regular city water supply for your kitchen, and another set connecting the rain water tank to the toilet. What do you do when the rainwater tank is empty? You need a third pipe from the toilet to the city water supply, and that pipe would need a valve to keep it closed most of the time, (so it wouldn’t be used unless the rainwater tank is empty.) Is there a way to do that automatically,or do you have to turn the valve manually? And is there also an electric pump to turn on? ---
**Author:** ![sisu](https://avatars.discourse-cdn.com/v4/letter/s/df705f/32.png) [@sisu](https://boards.straightdope.com/u/sisu)\ **Post date:** [December 3, 2013, 6:14am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/10 "2013-12-03T06:14:59Z")
Yes there is an electric pump and when the tank is empty it auto switches to mains water. It’s a pretty straight forward set up and any half decent plumber could install it. Yes it costs money and uses power etc but water saving down here was pretty important. We didn’t drink the water but my mum only has tank water and drinks it straight. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [December 3, 2013, 6:30am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/11 "2013-12-03T06:30:06Z")
There’s lots of them. They are all over to provide water for birds, primarily Galliformes ([pdf](http://utah.ptfs.com/Data/Library2/publications/lr001071.pdf)). Oh you wanted for human purposes, then? Hunters use them to find the birds. The locations are usually hard to find unless you shell out ~$50 to the DoW. ---
**Author:** ![bluezooky](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bluezooky](https://boards.straightdope.com/u/bluezooky)\ **Post date:** [December 3, 2013, 6:36am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/12 "2013-12-03T06:36:01Z")
> [@Musicat](#): > > So your critters are so circumspect as to never poop on the roof? > > Just what kind of filtration system do you have to make that roof runoff potable? A simple screen wouldn’t work, and a reverse osmosis system is expensive and slow. Ultraviolet purification? In Australia you would have a bypass and float system so the first bit of rain washes the roof and is dumped before you start filling the tank. I’d be more worried about lead pollution or pesticides than a bit of bird shit . ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [December 3, 2013, 7:36am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/13 "2013-12-03T07:36:27Z")
My fraternal grandparents had a [wooden cistern](http://www.hatteras.biz/images/cistern1.jpg) for cooking and drinking water. The well water had too much iron in it and tasted horrible. The cistern water was pretty good. ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [December 3, 2013, 7:42am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/14 "2013-12-03T07:42:37Z")
> [@aceplace57](#): > > My fraternal grandparents. [hijack]Huh? What’s a Fraternal grandparent? did you mean Paternal?[/hijack] ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [December 3, 2013, 7:59am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/15 "2013-12-03T07:59:44Z")
> [@chappachula](#): > > [hijack]Huh? What’s a Fraternal grandparent? did you mean Paternal?[/hijack] Grandparents that don’t quite look like you. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [December 3, 2013, 8:03am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/16 "2013-12-03T08:03:32Z")
Fraternal grandparents are your father’s parents. Maternal grandparents are your mom’s parents. > [@chappachula](#): > > [hijack]Huh? What’s a Fraternal grandparent? did you mean Paternal?[/hijack] ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [December 3, 2013, 9:15am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/17 "2013-12-03T09:15:26Z")
My grandparents are way cooler than my brother’s grandparents. ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [December 3, 2013, 9:31am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/18 "2013-12-03T09:31:33Z")
> [@thelurkinghorror](#): > > My grandparents are way cooler than my brother’s grandparents. I used to tell my brother that, too! (I was about 11 yrs old, he was 5) I’ve started [another thread](http://boards.straightdope.com/sdmb/showthread.php?p=16896719#post16896719) on this vital issue. And so far,( after 2 posts), I’m winning. 🙂 ---
**Author:** ![mbh](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@mbh](https://boards.straightdope.com/u/mbh)\ **Post date:** [December 3, 2013, 11:06am UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/19 "2013-12-03T11:06:53Z")
Before World War II, a lot of houses collected rainwater from their rooftops and collected it in underground cisterns. They used charcoal filters to clean debris out of it, and boiled it to kill bacteria. According to my dad, the annual cleaning of the cisterns was messy, time-consuming drudgework. With the advent of electric pumps, a well becomes much easier and more convenient. Also, where I live, I am not certain that we get enough rain to make it worthwhile. Most of the year, you would be getting most of your water from a well, anyway. ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [December 3, 2013, 12:12pm UTC](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333/20 "2013-12-03T12:12:45Z")
> [@aceplace57](#): > > Fraternal grandparents are your father’s parents. Maternal grandparents are your mom’s parents. Frater - brother Soror- sister Mater - mother Pater - father Paternal, Maternal is how you refer to grandparents - a fraternal inlaw would be an in law because of being married to your brother, a sororal inlaw would be one because of marriage to your sister. [Next page](https://boards.straightdope.com/t/why-arent-water-catchment-tanks-used-in-the-desert-southwest-of-the-us/675333.md?page=2)