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Rain Barrels

Rain barrels, sometimes called cisterns, are aboveground water storage vessels.  They capture rain runoff from a building’s roof using the gutter and downspout system.

A typical house has a roof area of 1,200 square feet and four downspouts that will each drain about 300 square feet of roof. That means a rainfall of 0.3 inches will fill a 55-gallon rain barrel placed under each downspout.

Rain barrels with a drainage valve can store water for use between rain events. When the valve is opened, the water empties out slowly, thus reducing runoff and increasing infiltration.

Rain barrels are a type of Best Management Practice (BMP) also referred to as Rainwater Harvesting that also includes cisterns, irrigation storage, and evaporative controls. Download an excellent fact sheet from the MN Stormwater Manual. Additional general information about how rain barrels can help reduce runoff from your home, including links to plans and suppliers, can be found in our Citizens & Schools - Home & Garden section. The U of Minnesota Extension Service also provides a Rain Barrel Fact Sheet.


Applications


Rain barrels help:
  1. Divert water from storm drain systems and thus reduce pollutants and the velocity of water entering local rivers and streams;
  2. Store high quality water for gardens;
  3. Direct overflow water away from building foundations to more desired locations;
  4. Reduce water and sewer bills, as well as electrical bills from sump pump usage.

Examples
City of Superior Rain Gardens
Superior, WI
This project demonstrates the effectiveness of rain barrels and rain gardens in a region with heavy clay soils, harsh winters, and deep frost.

Materials and Installation
  1. Choices::
    • Rain barrels can be purchased from a number of suppliers (a more expensive option) or be a make-at-home project (a cheaper, more labor-intensive option).
    • Rain Barrel Workshop
      Superior, WI workshops.

       

      Linked rain barrels
      Linked rain barrels.
      (image source: gardeners.com)

      Check with local authorities; many have inexpensive pre-made rain barrels or offer workshops to construct a rain barrel. There are frequent workshops conducted by Superior, WI Wastewater Treatment Plant staff.
    • Rain barrels:
      • Vary in size, usually from 20 gallons to 150 gallons. Larger structures can be designed and built, usually out of concrete or wood. Choice of size depends how much water needs to be stored.
      • Can be made from wood (recycled oak whisky barrels), heavy plastic (recycled watertight food grade barrels) or new garbage cans. Many commercially made rain barrels are molded heavy duty plastics. The wide array of choices allows for creativity when fitting barrels into garden landscapes and buildings’ architecture.
      • Are easily integrated into rain gardens, vegetable, flower, rock, or other gardens and green spaces.
      • Can be linked together to increase water capacity.
  2. Required Safety Features
    • The barrel should have a clamped or friction fit cover or a built-in exclusion device. This prevents animals or children from climbing in the barrel and subsequently drowning.
    • A screen cover is necessary to prevent mosquito breeding.
  3. Placement
    • Locate rain barrels under downspouts where rainwater can be most easily collected for transport away from building foundations into a garden or onto the yard.
      rain chain
      A rain chain provides added beauty to a rain garden. Click here for more information. Search for "rain chains" on the web for more distributors.
    • The base on which the barrel  will stand must be level and secure. A typical rain barrel will weigh over 500 pounds when full. Concrete block or pavers make good substitutes if a patio surface or driveway is not available. Concrete blocks or pavers also raise the barrel off the ground, which increases water pressure coming out of the hose.
    • Downspouts should be cut or flexible downspout hose can be attached, allowing a three-inch gap between the top of the barrel and the end of the downspout; this provides space for removing the lid to clean the inside of the barrel.
    • Overflow ports and hoses should be placed to drain excess water away from the building. If the forecast predicts heavy rain, connect a hose to the overflow port and run it away from the building – no one wants a barrel to overflow right next to the foundation.
    • Adding additional rain barrels can increase the quantity of water stored. Overflow from the first barrel can be passed to a second barrel by securely connecting its overflow hose to the next barrel. Remember that the additional barrels must also be securely placed.
  4. Building a Rain Barrel from Scratch
    For do-it-yourself projects, see construction directions below in the suggested references section.
  5. Using rain barrels to gravity feed water to a garden
    • Attach a hose to the spigot at the bottom of the barrel. Water is supplied as needed by adjusting the spigot.
    • A soaker hose that snakes through a garden will disperse stored water throughout the garden over a prolonged period of time. A 55-gallon rain barrel with a soaker hose takes about 12 hours to drain. A spigot in the middle of the barrel can be used to fill a watering can.
      • Success depends on the barrel being sufficiently elevated above garden level.
      • Occasionally an air lock can form in the soaker hose, this problem is easily remedied by providing a bleed valve at the terminal end of soaker hose.
      • To help conserve dispersed water, cover soaker hose with mulch.

Since a 1 inch rainstorm on a 1000 sq ft roof yields 623 gallons of water, here's one way to catch it all — in an 850 gallon tank:

850 gallon rain barrel

A small external or submersible pump can then be used for distributing the water when the water level is low. Of course, there are other containers and configurations that might be adapted to your landscaping. This one cost $650 and was purchased from plastic-mart.com. A website user pointed us to an 850 gallon tank for $435 at tank-depot.com (April 2008 w/o shipping).

Suggested References: Guidebooks, websites and pamphlets

  1. Our rainbarrel page in the Citizens and Schools section has further information, including additional links to plans and suppliers.
  2. Garden Simply- Teaching Sustainable Garden Practices
    Instructions on building a rain barrel from scratch and more.
  3. The City of Superior, WI,
    Its rain barrels page includes a link to a step-by-step  “how to” manual for making a rain barrel and information on rain barrel workshop dates and times.
  4. Graphic plans for building a rain barrel
    Covington Water District Seattle WA
  5. General information on rain barrels
    Metropolitan Council Environmental Services of Minneapolis.
  6. Rain Barrel Guide- How to use rain barrels for water collection
    General information on use of rain barrels with links to a variety of rainwater harvesting and gardening sites.
  7. Rebecca Chesin, a master gardener in Plymouth, MN has created a nicely illustrated web guide on constructing rain barrels.


Tips and Wisdom

  1. Cleaning of new barrels.
    Clean the inside of new barrels with a brush and a very weak hypochlorite solution (3/4 cup Clorox per gallon of water). Rinse barrel after scrubbing and dispose of rinse water properly.
  2. Painted rain barrelanother painted rain barrel
    Painted rain barrels from Superior, WI workshops.
    Painting rain barrels.
    Barrels can be painted to reflect personal taste or to better blend into the landscape or architecture. Paints must be able to withstand climate conditions and be compatible with the barrel material (for instance, plastic barrels can only take paint specially made to adhere to plastic).
  3. Management of heavy rain storms.
    Rain barrels fill very quickly in a storm;  the overflow must be directed away from building foundations. Connect a hose to the barrel’s overflow port and direct the water at least 6 feet away from the building foundation. Check the hose periodically to be sure it is positioned correctly. Another option is to use a diverter, such as the RainReserve Rain Barrel Diverter that redirects the water to your existing downspout system when the barrel is full. It also is designed to keep leaves and other debris out of the barrel.
  4. Winterizing rain barrels.
    Disconnect downspouts prior to the first hard freeze. Return downspout systems to original configurations or extend away from building foundations. Drain the rain barrel and turn it upside down to prevent freezing and cracking. Store hoses and mesh screens. While much of the literature about rain barrels cautions homeowners to take rain barrels "off line" in the winter/spring thaw, this hasn't been necessary at the demonstration project being conducted by the City of Superior, WI (see example above). Rain barrel/hose combinations can be drained of water and left hooked up with the spigots open. Such a winter season procedure was done without problems in winter 2003/4 and 2004/5 at the Superior Waste Water Treatment Plant., WI. Open barrel spouts should, as always, be directed away from building foundations.
  5. Maintenance.
    Rain barrels operate pretty much trouble free. However, periodic checks throughout the season will ensure success – hoses can be inadvertently moved out of place during regular yard maintenance, loosening attachments. Check that lids and hoses are properly placed and attached, that hardware is functioning properly, that no yard pests have found an entrance into the barrels, and that water is being dispersed in expected locations.


Limitations

  1. Rain barrels can collect a relatively small amount of water compared to the runoff from a roof during heavy storms or prolonged rain events. To handle larger volumes of water, rain barrels are best used with additional water management practices such as rain gardens.
  2. Winter freezes prevent effective use of rain barrels until spring thaw.
  3. Rain barrels may lack aesthetic appeal and thus extra expense might be incurred to build structures to hide or camouflage rain barrels.
  4. Steeply sloping land can hamper safe placement and function of rain barrels. Some additional cost will be incurred to build concrete pads or reinforced wooden platforms that will safely bear the weight of a full rain barrel.
  5. Care must be taken when building rain barrels to choose an adequate container. Material must be sufficiently rugged to survive the constantly changing outdoor environment and strong enough to withstand the pressure caused by the weight of 50 or more gallons of water.

For more information contact:
Public:
City of Superior Public Works Department  
City of Duluth Public Works Department
Storm Water Utility Operations