Developed by the Civic Garden Center of Greater Cincinnati

Introduction to Rainwater Harvesting

Harvesting Rainwater

• From simple 55 gallon drums to gigantic underwater storage tanks

• Catch water from roofs or pavement to use later for irrigation (or even flushing toilets or doing laundry)

• Logistics: legality, overflow, pollution

Hidden rainwater storage systems go underground or under buidlings/decks

Rain BarrelsPractical Considerations

• Locating your Rain Barrel– Location of your downspout– Proximity to the area you want to water– Uphill or level with area to water

• Other Considerations– Water pressure: higher the water level is the

more pressure you get– Gravity is your friend and foe

How Much Water?• A 1,000 square foot roof (an area 20 x 50 feet)

produces a volume of approximately 623 gallons of water for every inch of rain. (0.623 gal/square foot)

• An average rain barrel holds around 50 gallons of water.

• The good news is that your rain barrel will fill up very quickly - the down side is that you need to have a way to manage the overflow.

• Directing rain water from your roof into the storm water system is required in most municipalities so rain barrels need to have an overflow so extra water doesn’t flood property

Managing Rainwater Overflow• Prevent erosion damage, basement flooding for

you and your neighbors• Conform to municipal building codes. • Return to storm water system via a direct line

from your rain barrel• Use of a diverter installed on your downspout

above your rain barrel• Direct overflow into an adjacent municipal storm

drain • Direct overflow to a Rain Garden or Swale

Diverters: getting water in (and out)

Diverter D.I.Y.

Faucets and Overflows: getting water out

What you don’t want to happen!

Overflow outlets should be as high on the tank as possible to maximize storage capacity

¼ turn, full flow faucets have the best flow with just a simple turn

Faucets should be installed as low as possible on the tank so you can get all the water out, but make sure you have room under them.

Care and MaintenanceEmpty and rinse out your rain barrel at least once a year.

Mosquito Control:• Screen: If your barrel is open at the top• Vegetable Oil Treatment: If you do notice Mosquito hatchlings,

add a tablespoon of vegetable oil to the water’s surface.•

• Drain and Clean: At the sign of Mosquito hatchlings drain and rinse out the barrel.

• Mosquito Dunks: Bacillus thuringiensis (israelensis) or BTI kills mosquito and black fly larvae for 30 days or more.

Algae: Keep sun out with opaque container

Problem Solving…• No Roof?• Algae?

Winterizing Rain Barrels

Rain Barrels on Parade

This is just scratching the surface!

• There are so many creative ways to capture and store rainwater.

• After your site visit, do some browsing online to explore different materials, arrangements and solutions for rainwater harvesting.

• Make sure you are prepared to answer questions regarding the capacity of the system: how much water is flowing into it and how much will be used, how often.