Sizing & Design

STEP 1. Observe your roof runoff. Note where you have existing roof gutter downspouts, roof valleys or edges that drain large amounts of water.

STEP 2. Calculate the runoff volume. To determine how many rainbarrels you need and whether you should designate an area to directthe rain barrel overflow, you need to know the volume of water thebarrels will receive during a typical rain storm. Designing for a 1-inch storm will capture most of the runoff volume as long as thebarrels are emptied between storms.

Complete steps A-D to calculate runoff volume:

A) Calculate the square footage of the drainage area:  DRAINAGE AREA LENGTH (ft) X DRAINAGE AREA WIDTH (ft) = DRAINAGE AREA (ft2)

B) If multiple areas will be directed to the rain barrel, calculate thesquare footage of each and add them together.

C) Find the volume of stormwater from the total drainage area fora 1-inch storm by dividing the drainage area by 12 to convert theinch to feet:

TOTAL DRAINAGE AREA (ft2) ÷ 12 INCHES = STORMWATER VOLUME (ft3)

D) Most rain barrels give the holding capacity in Convertthe cubic feet to gallons by multiplying by 7.48.

STORMWATER VOLUME (ft3) X 7.48 GALLONS = STORMWATER VOLUME (gallons)

STEP 3. Determine how many rain barrels are needed. Attempt to capture volume from a one-inch storm.

STORMWATER VOLUME (gallons) ÷ RAIN BARREL CAPACITY (gallons) = # OF RAIN BARRELS NEEDED

STEP 4. Address the overflow. Be sure to note where the overflow will go during large storms. Avoid directing the overflow next to building foundations. Plan to use a splash guard, install a soaker hose, or build a slight swale to direct overflow away from your home and into an area where it can be absorbed, such as a naturally vegetated area or a rain garden.

You may want to complete the fist 2 installation steps prior to the workshop as well.

Installation

STEP 1. Level the area. Once you have determined where you want your rain barrels to go, level the ground surface. You can use crushed stone or mulch to stabilize the ground.

STEP 2. Install blocks or stand. Elevating the rain barrel isnecessary to allow room for a watering can, bucket, or hose attachment under the spigot. Elevating the barrels will also create stronger water pressure. Place the blocks or other materials to create a stand on the leveled ground andrecheck for level. Adjust as needed to achieve level. TIP: Your rain barrel should be secured on a firm, level surface. A full, 55-gallon rain barrel weighs over 400 pounds.

STEP 3. Connect the downspout to the rain barrel. Flow diverters allow you to easily direct flow from your gutter downspout into your rain barrel. To install the diverter, temporarily place the rain barrel on the blocks to mark where the diverter needs to be installed. Cut the gutter and install the diverter per the instructions, at a height that allows the water to flow from the diverter into the barrel. If not using a flow diverter, the gutter downspout can be directed or connected directly to the barrel.

STEP 4. Install the rain barrel.

1. A) Place the rain barrel on the blocks or
2. B) Direct flow from gutter downspout or diverter into the
3. C) Direct the overflow hose from the rain barrel to avegetated area or another stormwater practice, where it can soak into the ground