Rainwater Catchment and Use
Guest Article for the Tallahassee Democrat July 5, 2013 By Mark Tancig
Photos by Laura Ciociola: Four 55 gallon containers placed under roof eave. This 55 gallon container with a spigot is placed under the valley of a roof.
Collecting rainwater is a common practice often discussed by proponents of the Sustainability movement, typically through the use of rain barrels or other water holding containers. The practice goes back thousands of years to the beginnings of civilization as a way to provide irrigation for food crops and human consumption, and was common until only a few generations ago. Nowadays, everyone in Leon County is connected to either municipal water supplies or a well with a pressurized tank, but we can still make use of the rainwater that spills off our homes, sheds, and other buildings.
The benefits of collecting and using rainwater include free irrigation water, reducing potable water use for landscape areas, reducing stormwater runoff from your property, and increasing awareness of how much water you use for outside (non-potable) purposes. All of these benefit your pocket book, the environment, or both.
The first step to collecting rainwater is getting the container to capture and store the water. Containers can range from 5 gallon buckets to 250 gallon tanks or, if you really want to go all out, a series of 5,000 gallon cisterns (the Leon County Extension Office recently completed a project that can collect up to 40,000 gallons). The most commonly used, affordable, and readily available container is a 55 gallon plastic drum with or without modifications. Helpful modifications include a spigot, an overflow, and a removable, mesh-screen lid for easy access and to keep out mosquitoes.
Next, the container needs to be placed where rainwater can be readily collected. The ideal site is under the eave of a building’s roof, especially near a roof valley. Placing the container under a gutter downspout increases how much water will be collected but does require cutting the downspout to fit the container. Make sure the container is stable since a full 55 gallon drum will weigh over 400 pounds (about 8 pounds per gallon). Larger setups – 250 gallon and above – will likely require some basic plumbing know-how, carpentry skills, and additional materials.
The next step is the easiest but requires Mother Nature’s cooperation – Rain. Some folks have experienced that as soon as you setup your container the drought begins. For others it seems to bring on monsoons. When the rain does come, it’s a good idea to monitor how well your container is collecting water in case adjustments are needed.
The last step is using your collected water. Collected rainwater can be used for many purposes including vegetable gardens (see below), flower beds, patio plants, trees and shrubs, bird baths, washing off bowls, buckets, your dirty hands, sand toys, etc. Ideally, your container has a spigot and it’s as easy as connecting your hose and turning it on. This works best if your rain barrels are uphill from your target watering area. Raising the container on blocks can help but remember to make sure it is stable. Submersible pumps can be used to increase pressure and/or water areas uphill from your container. You can also dunk 1 gallon jugs, 5 gallon buckets or various size watering cans into the container.
Using the collected water for human or animal consumption is not recommended due to contamination from the atmosphere, roof surface, and/or biological growth during storage in the container. Of greatest concern are metals leached from roofing materials (asphalt shingles, tin, aluminum) and bacterial growth due to environmental conditions (water, light, warmth). Research on harvested rainwater quality has found that while the collected water does not meet drinking water standards, most pollutants are at low enough levels acceptable for many non-potable uses. When using the collected rainwater to irrigate edible plants, it is recommended that the water be applied directly to the soil to minimize potential contamination.
Mark Tancig is a Water Resource Specialist with the Leon County Public Works. For more information about gardening in our area, visit the UF/ IFAS Leon County Extension website at http://leon.ifas.ufl.edu. For gardening questions, email us at Ask-A Mastergardener@leoncountyfl.gov