Friday, January 31, 2014

Rainwater Collections

While the rest of the nation is dealing with Global Wierding and cold winter weather California is bracing itself for a serious drought and early fire season. The low to no humidity and Santa Ana winds create the perfect storm for wildfires. California is also gearing up for what the Old Timers call, "Water Wars." 
This sounds like a perfect plot A&E or Lifetime reality show. 

In the mean time how do small farms handle the lack of water?

On the Viking Homestead we started to collect rain water in barrels. We do not have just one barrel on each spout. In total we have about 500 gallons of rainwater stored which we use to water the gardens, provide water to the animals. We also have a 500 gallon cistern that doubles as a fish pond. 

The set up and kits are real easy and anyone can collect their own rain water. Here is how.  

1. Calculation on how much rain will come off the roof?
  • Each area in the nation has different precipitation and humidity factors. Through the use of Google it's easy to discover what your local areas precipitation humidity factors and rain levels are for calculation. For the San Diego County the "rainy season" is February. 
  • Find the area of your roof. That is the area (Length multiplied by width) which also includes the overhangs. Keep in mind that your roofs condition can also effect the amount of rain that is collected. Keeping gutters debris free is also important. 

A well designed system can collect from 75-80% of the water off the roof.
sooooo ... 
Length (in feet) x Width (in feet) x 144 (square inches per square foot) x 0.75 = Area (in square inches)
Be pessimistic and guess only 75% will be successfully collected :(

Check your average rainfall in inches (or for any given rainy day)
Area (in square inches) x rainfall (in inches) / 231 (cubic inches per gallon) = Volume (in gallons)

Annual average rainfall will give you an estimate of what you could collect in a year
Local Storm Report will give you an estimate of what you collect on a rainy day.
You can even purchase a simple rain gauge for your yard to see exactly what fell on your house instead of the county average/estimate. 

2. Barrels. 
  • This is important. DO NO USE barrels that have contained ANY kind of fuel or motor oil. Barrels need to be food grade, rated for water collection and new. Recycled or re-purposed barrels, which we have, must not have had had toxic substance inside but can be used cautiously. Ours once contained food grade coconut or palm oil used in soap making. They can be used but we have had to build a filter system before it went into our cistern. Future post.
  • Barrel materials is personal preference. Our barrels are metal and we determined it by the weather we have in East San Diego County and cost. When deciding what kind of barrel you use keep the weather in mind. Barrel costs can run between $0- 1,000+. 
  • Keep this in mind. The water coming off the roof is not immediately drinkable, it is non-potable. There are too many 'not-good' things (tar, bird poop, mold, soot, you get the idea). Which means you can water your garden, farm and lawn from the barrel, but you need to filter it before you drink it.

3. Rain Barrel Diverters. 

It is up to you if you want the rain water from your gutters to go into one barrel or many. We have diverted the water from the gutters using Fiskars Rain Barrel Diverter Pro from ACE Hardware. Check out their site here. ACE Hardware also has Rain Reserve Rain Water Diverter too. Super easy to install. 

4. Cisterns

Southern California, especially San Diego County, has a very long history on the use of cisterns to collect water. This is a personal decision. We decided to create a cistern. Ours happens to be a converted and re-purposed hot tub. It's not pretty but it holds an additional 500 gallons of water. This Spring we plan on building an additional cistern/pond for the new garden. 

The Diverter on the down spout of the gutter drain
Rain barrels connected to diverter pipes that lead to hoses into each 55 gallon barrel.  When it rains the water is diverted from the gutters down the pipes into each of the barrel.
Barrels sit on re-purposed pallets. It doesn't take long to fill one barrel.

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