To recap the journey water makes on my farm:
Solar distilled water in the atmosphere
Falls as precipitation
Barn roof
Gutters
Collection Barrels
Pumped up to elevated tank (Via this DC or solar powered pump)
Gravity fed to irrigate plants OR Gravity fed to water animal/fill mobile tanks OR Gravity fed through filters into potable water tank
The last main hurdle of settling on the property is purifying the rain water that has run off the metal barn roof that has been treated with who-knows-what then stored in petroleum based tanks that my leach additional undesirables. Here is the catch, I don’t want to have to use power whatsoever to purify the water (excepting my DC solar pump).
First of all, I plan to purify water for drinking, bathing, washing dishes, cooking and any other miscellaneous needs. Between all of those uses I will conservatively require about 10 gallons a day of purified water. How can I do this without additional energy use?
The first step is a basic filter to remove debris and extend the life of later components. A simple layer of gravel then sand should do the trick.
Here is the gem: Ceramic. During manufacturing, sawdust and silver is mixed into the ceramic clay. When fired in the kiln, the sawdust combusts leaving behind microscopic channels that allows water to travel through the ceramic while bacteria are too large to fit. Silver impregnation provides a hostile surface for microbial activity. A simple scrub with an abrasive sponge removes the top layer of ceramic and refreshes the filter. I haven’t decided on a specific filter yet, but this one is along the lines of what I am considering.
Lastly, a replaceable and homemade activated charcoal filter will remove any chemicals that have leeched into the water on its journey to my farm. With the filter medium available in various quantities, it will be simple to incorporate the homemade and changeable filter into my design.
The last piece of the puzzle is a storage tank. I would prefer a non-petroleum based tank to store the fresh water. Preferable stainless steel and something that could tolerate a bit of pressure when pumping the water out. Does this ring any bells with anyone? If I can legally find a 15.5 gallon half barrel beer keg to use, I will remove the spear and add my own fittings. FYI, most beer kegs including the ones for sale on craigslist are property of the beer distributor who issued the keg when it was full of beer. Any you come across second-hand are technically stolen unless the seller can prove otherwise. Even though I personally view the legal requirement to use a distributor is right up there with cartels and acts a barrier to entry for smaller guys, I’ll still find a keg through legal avenues. Do whatever aligns with your ethics!
Regular water testing will ensure my system is safe and continues to be s0 as it ages.
With the exhaustive calculations for gutter and downspout planning complete, the next hurdle is for containers to collect rainwater. Craigslist to the rescue!
While I could pick up the typical blue 55 gallon plastic drums for around $40 each, I could spend double that for the roughly-cubic 300 gallon containers in the metal mesh. I plan to order at least 5: 1 for each of the 4 barn downspouts and one for the hayloft of the barn. Since the time of writing the draft initially, I have purchased 4 300 gallon tanks which you can read about here.
Why one in the hayloft? I plan to utilize a DC solar powered pump to push the water from the rain collection tanks up into the hayloft in order to gravity feed most paddocks as well as the fruit and vegetable garden. Ideally I would put a tank in the top of the unused silo to gravity feed the entire property, but that my be an engineering feat beyond my ability.
I also want a sixth barrel of equal or lesser size to mount on a trailer in order to more-easily water the furthest paddocks when animals are present.
WARNING: This post gets dense!
Rainwater collection is another vital aspect of my farm operation. While a well is drilled, pumped and plumbed, I would prefer to save its operation for emergencies. I will be designing a system that uses as little energy as possible.
An aspect of large initial investment will be to instal gutters on the barn. Its 60 foot by 80 foot pitched roof serves as a perfect mechanism to harvest solar distilled water, aka precipitation. I want to do my own legwork in designing a system before I contact installers for quotes. GutterSupply.com has available a resource in this PDF Proper Gutter and Downspout Sizing.
An important piece of data to acquire is the rainfall intensity over a 5 minute period for 10 year and 100 year rainfall events. The National Oceanic and Atmospheric Administration (NOAA) provides a tool that allows you to retrieve data for a specific location either visually by panning and zooming in a map or by inputting coordinates.
Following the sample calculations found on page 6 of the Gutter Supply publication using my barn and location, the process is as follows:
Total roof area in two dimensions is 80 ft *60 ft = 4800 square feet
Roof pitch is vertical rise/horizontal distance from start to end of rise is 15 feet vertical over 30 ft horizontal * 12 inches/foot = 6 inches per foot (on my barn)
According to Table 1-1 in the Gutter Supply publication, the constant for my roof pitch adjustment = 1.10
Therefore roof area adjusted for pitch is 4800 square foot * 1.1 = 5280 square feet
Number of downspouts desired = 4 (my preference)
Roof Area covered by each downspout is 5280 square feet / 4 downspouts = 1320 square feet per downspout
Because of the poor amount of cities represented in the PDF, I compared my rainfall to a few cities using the NOAA tool. Knoxville had a 5 min rainfall total of .440 inches while my location has .437. Close enough.
Per the terribly formatted Table 1-2 in the PDF, 1 sq inch of gutter can drain 180 square feet of roof area. So 1320 square feet / 180 = 7.333 square inches as a minimum per downspout.
Finally, comparing the figure of 7.33 square inches to the Table 1-3 in the PDF shows that 4 inches of any shape gutters would perform adequately in a 10 year rain event.
Following the final 3 steps shows that I would need a minimum downspout size of 10.15 square inches in a 100 year event at .690 rainfall intensity. 4″ gutters would still serve in every shape except rectangular corrugated.
Wow Bravo if you stuck through that. None of the other posts in this series will be this technical!
thegreenergrassfarm 