# Does every island have a spring? **URL:** \ **Category:** Factual Questions\ **Created:** [June 30, 2015, 5:38pm UTC](https://boards.straightdope.com/t/does-every-island-have-a-spring/723882 "2015-06-30T17:38:28Z")\ **Posts on this page:** 3\ **Page:** 2
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [July 1, 2015, 11:00pm UTC](https://boards.straightdope.com/t/does-every-island-have-a-spring/723882/21 "2015-07-01T23:00:19Z")
> [@Blake](#): > > Sigh. Doctor Death is back to his old tricks. Make a ridiculous pronouncement, then spend days weaseling around to get out of it. > > 1. Try reading again. Those were figures for a simple hole in the ground. > > 2. You didn’t say you might possibly lose more water in 24 hour day than you can get from a solar still. You said that you will inevitably lose more water from building a still than you ever can get back from the still. That claim is utter bollocks. 1. From your first cite: [http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1883&context=cee\_facpub](http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1883&context=cee_facpub) “ABSTRACT SOLAR earth-water distillation is a means of extracting moisture from an earth medium. Three designs of the hot-box type of solar earth-water still were tested using wet or saturated sand. The designs included: low height with reflective interior siding, tall height with reflective siding and tall height with absorptive siding. The daily volume of distillate from the different designs was compared. A twenty-centimeter-tall still with reflective siding produced significantly greater yields than one twice as tall. No significant difference in the b yield between tall stills with light-absorptive versus Light-reflective interior siding was found. A regression equation was developed to predict water production for a low still with reflective siding and a sixteen-degree cover slope. Independent variables included soil moisture, solar radiation and maximum and minimum daily temperature.” They pictured but _did not test_ the “simple hole in the ground” still. 1. My exact words "Note that the much vaunted “solar still’ made by digging a pit and putting a part\* over it is useless. You lose more water making one than you can gain.” - I meant tarp, auto-correct “fixed” this. So again- the much vaunted "solar still’ made by \*digging a pit and putting a tarp over it \*- is useless. You lose more water making one than you can gain. The cites in my previous post say exactly that: [https://books.google.com/books?id=rW...stills&f=false](https://books.google.com/books?id=rW...stills&f=false) "_When my students build solar still I keep track of the water they consume while doing so. Without exception…they always lose much more water in the form of sweat than the still provides_"**98. 6 Degrees: The Art of Keeping Your Ass Alive By Cody Lundin** > **[Solar still](https://en.wikipedia.org/wiki/Solar_still)** > > A solar still distills water with substances dissolved in it by using the heat of the Sun to evaporate water so that it may be cooled and collected, thereby purifying it. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight. > Still types include large scale concentrated solar stills and condensation traps. In a solar still, impure water is contained outside the collector, where it is evaporated by ... _The system is inefficient for how much work is put into it versus the water output.[5] In desert environments water needs can exceed 1 US gallon (3.8 L) per day for a person at rest, while still production may average 8 US fluid ounces (240 mL) per day.[5][6] Even with tools, digging a hole requires energy and makes a person lose water through perspiration; this means that even several days of water collection may not be equal to the water lost in its construction_ [https://books.google.com/books?id=g0...20work&f=false](https://books.google.com/books?id=g0...20work&f=false) [http://beforeitsnews.com/survival/20...k-2491454.html](http://beforeitsnews.com/survival/20...k-2491454.html) \* “Several real-world tests have shown that you sweat more moisture building solar stills than they produce.”\* ---
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [July 1, 2015, 11:59pm UTC](https://boards.straightdope.com/t/does-every-island-have-a-spring/723882/22 "2015-07-01T23:59:45Z")
> [@Aeschines](#): > > I was thinking about survival on small islands in the ocean. One of the first things they tell you about survival: find water. Follow a stream to a spring, etc. > > So you find yourself on an island in the middle of the ocean. It’s small but not too small for survival. There are trees growing, etc. > > Could you expect to find a spring on such an island? Or would you have to depend on rainfall for water? What would be a good strategy for storing water either from the spring or from rain, assuming you arrived on the island with only the clothes on your back? > > Thanks! No, not even close. Having lived for almost a year in the Marshall Islands, I assure you there’s nothing “fresh” about any water near those islands. It rained enough that rain water could be saved (even on the runway) for use. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [July 2, 2015, 2:08am UTC](https://boards.straightdope.com/t/does-every-island-have-a-spring/723882/23 "2015-07-02T02:08:41Z")
> [@TallTrees](#): > > On this island, a not too long ferry ride from a major city, a local told me that it was common to need to top-up one’s tank during the dry season from a water truck. On Bermuda, not sure if that’s available. Heck, people do this in Michigan when it’s particularly dry. Typically rural places that still have crock wells instead of drilled wells. If the shallow water table drops, you can order a tanker from the closest city top it off with city water for you. [Previous page](https://boards.straightdope.com/t/does-every-island-have-a-spring/723882.md?page=1)