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How to Make a Rain Water Harvesting System Using Soda Barrels

Creating a home rain water harvesting system with readily available soda barrels is your first step to contributing to a more sustainable community. The process is very simple. You may already have rain gutters and just need to connect the down spout to the barrel. Our example here is a little more complex, involving several barrels and a rain gutter installation. Take from it ideas that you can use to customize your rain harvesting system to the space you have available. Once you get started, you'll be surprised how creative the mind can become installing rain barrels and using the water.

  • Rain Water Harvesting System Background

    After discovering Brad Lancaster, author of Rainwater Harvesting for Drylands and Beyond we wanted to begin water harvesting. We operate a mail order cactus nursery from our back yard. The nursery has been growing for the last six years. We've rebuilt shelving three times to accommodate the increasing plant inventory. As a result, we're just about out of space.

    We live in a desert climate that gets four inches of rain PER YEAR. We depend on a watershed that comes from hundreds of miles away in the Rocky Mountains. Needless to say, our water bill is expensive. So any water that can be retained on-site after a rain shower is a bonus. So with the desire to create a rain water collection system, we only needed to determine where to put it and what kind of holding tank to use.

  • Where to Install the Rain Water Storage Tanks

    Being tight on space, we considered many different styles of rain barrels. They are available in just about any size and shape and designed for above ground as well as below ground installation. Here are some examples:

    • Plastic Water Tank -

      These tanks were originally designed for agriculture to store fluids such as fertilizers and irrigation water. They range in capacity from 10 to 10,000 gallons. They are available in food grade or non-food grade quality. You can get short fat ones or tall thin ones depending on the space that you have.

      rain water storage tank
      A Tall Rain Water Storage Tank

    • Trash Cans

      Trash cans are a very inexpensive and accessible way to store rain water. There are many examples of these posted on the Internet.

      using trash cans for rain barrels
      Using Trash Cans For Rain Barrels
      using trash cans for rain barrels
      Connecting the Faucet and Tubing;
      Elevating the Cans for Increased Water Pressure

    • Used Tanks

      You can use an old kerosene tank to store water. Just be sure the water is used for the plants and not drinking.

      kerosene tank for rain harvesting
      Kerocene Tank for Rain Harvesting
    • Your Ideas Here
    • Soda Barrels

      Soda barrels or car wash soap barrels are 55 gallon barrels that have been used for other purposes. They are typically available from local recyclers, beverage vendors and servicers, and car washes in your town. The costs typically range from $5 to $25 for used barrels.

      soda barrels for rain harvesting
      Soda Barrels are a good building block for a simple rain water barrel system

      They are very handy and can be easily modified for rain harvesting. We chose these for our rain harvesting project because they are modular, meaning we can start with one or two, then add more as space and budget allow.

      soda barrels for rain harvesting
      Versatile Soda Barrels Can be Assembled Vertically or Horizontally
  • Choosing a Location for Our Rain Barrels

    As we mentioned before, storage space for the rain barrels is very limited because we have so many plants. Also, the long sides of the house face north and south. The south side has the landscape because the yard area is much larger than the north side. The north side faces our neighbor's house. There is only room for two walkways, theirs and ours. We considered placing the rain barrels on the south side, but determined that there is no need to do that because the water coming off the roof will infiltrate the ground and be used by the shrubs and trees planted on the south side of the house. In addition, the south side roof is sectioned, whereas, the north side is one long straight length almost 60 feet (20 meters).

    So, we choose to put the rain gutters on the north side and drain that side of the roof to the back yard. We have the plants stacked on shelves. One shelf rack is near and parallel to the back of the house and is very tall. So we chose to place the first set of four barrels under that shelf rack. It worked out great because the barrels didn't take any more floor space in the back yard and they were using space that was too dark for plants.

    The only remaining decision was to decide which orientation to place the barrels: vertically or horizontally. Placing the barrels vertically up-side-down allows maximum fill of water and maximum drainage. However, if you do not have the vertical space to place them, then you are forced to lay them down horizontally. You'll loose about 10% of you capacity with a horizontal installation. We had to horizontal because of our space limitations.

  • Purchasing the Rain Barrels

    You can check with any local restaurant, bar, casino, or automated car wash. They may not have the barrels themselves, but can refer you to the company that services their fountain drink server or car wash soap dispenser. We found a company that specializes in barrels of all types, The Barrel Company, Inc. They sell not only used 55 gallon plastic drums, but new ones and barrels of other sizes and materials. Because the barrels were previously used for soda syrup, they always warn not to use the water for drinking.

  • Selecting the PVC Connections

    Common PVC plastic tubing and fittings were used to connect the barrels. You'll use two sizes of PVC tubing: 3/4 inch pipe is used for the output and 2 inch pipe is used for the input. There are two openings in the top of the barrel. Both of the these are threaded, which we used to connect the PVC. You'll want to use the larger pipe on top for over flow from the first barrel to the next when the rain is coming down hard. Otherwise, the smaller tubing on the bottom will be over taxed and the excess water will back wash out of the down spout opening.

    rain harvesting plumbing assembly
    PVC Connection Hardware is Simple

    Just a side note, we chose white PVC for our application, but you can use many other types of tubing available such as aquarium tubing, flexible black tubing, rain gutter pipe, or vacuum hoses. We just found PVC to be the best choice for our application because we had experience with it doing the irrigation system for the landscape.

    Since the smaller 3/4 PVC joints will be holding continuous pressure (the weight of the water) they will need to be glued. However, since the larger overflow 2 inch pipe will not be under pressure you can leave it un-glued. That way it's easy to maintain.

  • Building the Rain Barrel Foundation

    It is best to elevate the barrels as high as possible for increased water pressure coming out of the faucet. Cinder blocks are the most convenient. We used cinder blocks that had an indentation on one side that allowed us to anchor a 2x4 piece of wood. Then we screwed supporting side rail 2x4s to the anchored wood. This keeps the barrel from rolling when it is full of water. You'll want to stabilize the barrel very securely because it will weigh several hundred pounds when full. The PVC pipe and anything else around won't be strong enough to keep it from rolling once it gets started.

    rain harvesting barrel foundation
    A good foundation is simple to make
    and prevents your barrel from rolling when full.

    Before we assembled the wood pieces, we set the height by adding either a standard cinder block or two inch thick paver stones. No mortar or cement were needed. We also used a level make sure the final resting place for the barrel was nice and flat. L-brackets were used as well as one long three to four inch screw was used to secure the side rails to the anchored wood.

  • Mounting and Connecting the Rain Barrels

    Before piping the barrels together, we made sure they fit nicely on their new foundations. The barrels are 24 inches wide by 36 inches tall. So if you want to place two barrels next to each other, make sure the foundations are far enough apart.

    You'll need an assortment of elbows, tees, 4-ways, and slip-to thread PVC couplers for the assembly. Cut all the pipe pieces and make sure they fit before applying glue. However if a piece is a little too short or too long, that's okay, because the barrels can still be rotated a bit to make the pipe fit. Once the assembly is finalize pull the smaller 3/4 parts apart and glue them. Apply the glue to the pipe, not the inside of the coupler. There should be just enough glue to make a thin coating around the bottom 1/2 inch edge of the pipe. Twist the pipe with the wet glue into the socket. It should slide all the way to the stop edge inside the coupler. If not, you have about 10 seconds before the glue dries. You can use a mallet to force the pipe all the way in.

    At the outlet pipe, you can add a ball valve. And to the ball valve you can add a coupler that allows you to attach a water hose. Here is the final assembly of the first phase of our rain barrel catchment system.

    final assembly of first phase of rain harvesting barrels
    The low pressure top plumbing is not glued.
    The high pressure lower plumbing is glued.

    Some other things need to be included in your assembly. You need some place for the extra rain water to go once all the barrels are full. You would put a hole on the top side of the last barrel and attach a pipe to carry the water away from the house. You'll also need to make sure your pipes are level or slightly down sloping for water flow. If you are installing a lot of barrels, you may need to sacrifice some of your foundation height to achieve good rain water flow through the barrels and tubing. Consider breaking up your connecting pipes so that no more than four barrels are connected on the lower outlet. This allows for easier maintenance and higher reliability. You always want to make sure that at least the first two barrels are connected at the top by a large diameter pipe to allow for pressure overflow during heavy rain events. Otherwise the rain water will back wash out of the down spout hole in the first barrel.

  • Selecting the Rain Gutter

    You can select either plastic or stainless metal for the rain gutters. We found plastic to be very easy to work with and the pieces just snap together with no tools. If instructions are not included, you can download them from the manufacturer's web site.

  • Installing the Rain Gutter

    Follow the instructions even before you buy the hardware. It may look simple, but you could miss some steps that could cause re-assembly, wasting your valuable football afternoon.

    rain master gutter instructions
    Follow the instructions to install your rain gutter.

    Attaching the rain gutter to the roof's edge should not take more than two hours. It is a simple matter of screwing or nailing the brackets to the roof fascia, then snapping the gutters together and in place. The slope is going to be nearly flat, something like one inch drop for every 20 feet of gutter length.

    rain gutter for rain harvesting
    Plastic gutters are very neat and easy to work with.

    Your down spout assembly consists of three components: a gutter outlet, two to four 45 degree elbows, and some down spout tubing. Like the rain gutters, the assembly just snaps together. You just need a few securing screws to keep the pipe from coming apart in high winds.

    rain harvesting down spout assembly
    Down spout assembly is a snap.

    The bottom end of the down spout should fit into a hole cut into the top of the first barrel. The hole should be fitted with some kind of filtering material to keep leaf litter from entering the barrels.

    rain harvesting down spout assembly
    The bottom of down spout assembly should fit in hole of first rain barrel.
  • Filling the Barrels with Rain Water

    Once the assembly of the rain barrel and rain gutters are complete, you'll be amazed at how simple it was. Now it's just anticipation for the next rain to fill them. One good rain, and they are bursting with water. You'll want to add more right away, because you'll hate to see free water being wasted.

  • Suggestions for Using the Rain Water

    You can use a watering can, 5 gallon bucket, or other handled container to water your plants. If you need to get the water to a higher place or long distance, you can attach an electric pump to the output to get pressurized water. You can even power the pump by adding a solar panel and battery. We use flat cement mixing pans to soak our potted plants thoroughly when needed. This conserves the most water.

    Keep the light away from the barrels. Light causes algae to form. You can paint the barrels a dark color or place them in a location that receives minimal light.

  • Other Tips for Rain Water Enjoyment

    The rain water can be purified using equally simple non-technical means. Using a slow sand filter, you can clean the water by placing sand in a container such as a barrel. A biological film forms on the top of the sand as water flows through. The film contains beneficial microbes that remove pathogens or harmful substances. As time passes, this film gets thicker and slows down the flow of water through it. Only the very top of the sand impedes the flow of water. Because the water moves slowly through the filter, individual grains of sand down to 40 cm (13 inches) below the surface become covered by a biological film that also catches and destroys bad things. This below surface film does not slow the water down enough to cause a problem. This part of the filter does not need cleaning and should not be disturbed.

  • Universal Rain Harvesting Principals

    We've found rain harvesting to be extremely useful in desert climates. However, the same principals can be adapted to just about any climate or country. In other parts of the globe, like Australia, the locals are serious with their contribution for a better water sustainability. The government is even helping to achieve this. Rainwater tanks are used and supplied to better improve rainwater collection and harvesting. In addition, suppliers like also help educate the people as to proper installation, maintenance, usage and even assist homeowners choose the right tank for their use.

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