Building a Solar Still

by Jason Akers from http://www.theselfsufficientgardener.com. The Self Sufficient Gardener is a blog and podcast about growing your own food and living off the land.

For some reason, when I was a kid, I made it my business to know as many bushcraft skills as I could possible learn. One of the first I picked up was actually from a young-adult fiction book called Deathwatch. In the book, the protagonist is being pursued through the desert and must rely on his survival knowledge to evade and finally dispatch his pursuer. One of the things that allowed the book’s hero to do this was a device called a solar still from which he “made” fresh water. The book did an inadequate job of describing the still so I was forced to beg and plead my uncle (a member of the ANG) out of a copy of the military’s survival manual.

As I held those pages in my hand reading about how to build a solar still I knew immediately that I had learned one of the most valuable survival skills possible.

A solar still is nothing as magical as perhaps stories of my childhood makes it seem. Simply put, it is a hole in the ground with a cup at the center and bottom of the hole. Over the hole plastic is draped and a small rock is placed in the center. The plastic is secured at the edges. Newer versions actually have a drinking tube from the cup to the user. Who has a drinking tube at a time like this?

The solar still works through properties of evaporation and condensation. The water in the air and in the ground evaporates and forms a mist which floats upwards. The plastic traps the mist and the water collects on the plastic until it becomes heavy enough to drip off the center and into the cup. This process can be amplified by placing moist plant material in the bottom of the hole as green plants transpire and release water through pores. If I understand correctly you can even place saltwater in the hole and the still will desalinate it as it evaporates.

It must be said that there are disadvantages to this system. For one, it takes a lot of energy to build one. For another, the water you gather is only in amounts that will barely keep you alive in most cases. In addition, it must stay put for some time (overnight is best) to allow it to work, so its hard to travel.

However, in dry climates or in areas where freshwater is hard to find the solar still provides a means to sustainable fresh drinking water.

Review: Rain Reserve Water Diverter

Today’s entry comes from John Daleske. This is a great article because setting up rain harvesting is a big “to do” on my list for next year. It seems like a simple thing to install.

Review: Rain Reserve Water Diverter

by John Daleske

Capturing precious rain water will be critical in the future and important now for gardeners and permaculturists. It is also important as a back-up source for (mostly) potable water should there be a loss of one’s main water source.

The Rain Reserve water diverter

Rain Reserve makes a downspout diverter. I got a couple and have been testing them this past year. The design requires removing a downspout section, fitting the diverter in place, then screwing it in place.

Installation requires a way to cut the downspout (metal snips or a saw), screwdriver, and a drill. It took me about an hour.

As a closed system, it is supposed to keep mosquitoes and other water-loving critters out of the barrel. Rain water flows into the chamber. The center of the chamber has an upward extension with a hole at the top. Excess water and floatable debris flow out here. At the bottom of the chamber are the two outlets to which you connect the hoses.

The two hoses are pressure fit, though you could add clamps. One hose runs to a barrel. I installed two 50-gallon barrels.

The diverter input handles only the standard (American) downspout. All of my downspouts are the larger (6″), which required the reducer you see feeding into the diverter. That is an extra item, which I did not realize did not come in the kit. I am a little concerned that if we get a heavy rain for an extended period, the diverter would not be able to handle the excess flow, backing water up the downspout and eventually causing the gutters to overflow.

Rain Barrels hooked up to the diverter

I wanted the barrels high enough to let me water my garden using drip irrigation. The base is loose stacked cement block, two blocks high, leveled to provide a sturdy platform.

Note the sag in the feed hoses from the diverter to the barrels. There is no overflow pipe from the barrels. The intention is that the water fills up the barrel and up the hose at which point all other water fill flow out the center drain hole and down the downspout. The sag is caused by the weight of the water.

Also note the crimping of the hose on the left. When installed, the hose lines seemed the right length and could not have been cut shorter. I am trying to decide on the best way to correct that crimp. The barrel curently still fills up.

One of the main concerns I have is that this design does not handle debris wash from the roof to keep it from getting into the barrels. I have seen washer designs that collect the first few gallons from the roof, which will have the majority of small debris, then allow all subsequent water to fill the barrels.

The other concern I have is that this seems like it would not do well in areas with lower rain fall amounts. It allows too much water to just flow directly to the exit, only capturing a percentage of the overall flow.

For a small installation with just two barrels, it is an easy way to get started. For semi-arid or arid regions, I would look for a better way to capture a higher percentage of the flow.