Rainwater Harvesting For The Landscape Contractor

By Dave Ouwinga, VP of EasyPro Pond Products

All that is needed for a water harvesting system is rain, and a place to put it. The system can be simple; using contoured areas so that water flows directly to planted areas, or sophisticated, featuring storage systems that can contain captured water for later use. Photos courtesy of Dave Ouwinga, VP of EasyPro Pond Products

Fresh water may well become the petroleum of the 21st century. The growing scarcity of fresh, potable water, combined with long droughts is leading a trend toward more and more water conservation measures. These measures are sure to get more profound in the future. Landscape Contractors need only look at how many cities currently impose landscape water restrictions to see this trend.

The beauty of water harvesting systems is that the water captured is free and not subject to city water restrictions. It behooves the landscape contractor to encourage their landscape clients to invest in water harvesting. This is a win-win for contractors. Contractors get paid for installing the harvesting system, and the system will provide the water needed to service their clients' landscape watering needs.

Dig the containment hole so there's at least a minimum of six inches additional depth, as the tank typically gets covered with six inches of dirt. Once the hole is dug to the proper size, install the non-woven underlayment fabric. This material protects the liner from tree roots, sharp rocks, etc. Have one worker climb into the hole and step the fabric into all the corners, to ensure enough material is left on all four sides. Install the rubber pond liner over the underlayment fabric. Work the liner into the corners. If the pump vault is going to be located in the center of the reservoir, install the liner with equal amounts of extra liner on all four sides. If the vault is going to be installed along one edge of the reservoir, then keep most of the extra liner to the opposite side so it can wrap over the top of the cubes back to the vault.

Set the pump vault in the desired location. Install the vault riser(s) on top of the vault. Assemble and install the Reservoir Cubes on top of the liner around the pump vault. This will fill in the reservoir and create a large underground void for water. Fold the excess liner over on top of the reservoir cubes. The liner over top of the cubes prevents dirt from washing into the reservoir.

Water, Water, Nowhere

According to a May, 2000 Fortune magazine article: ''Water promises to be to the 21st century what oil was to the 20th century: the precious commodity that determines the wealth of nations.'' More recently, water-rich states near the Great Lakes have begun to set up coalitions and laws to protect their water wealth from the water-poor states around them.

Landscape contractors need only to look at the growing desperation in southern states, as a result of the states' rapid development and long-term drought, to see the writing on the wall. Like oil, fresh water will only become scarcer in the future while demands continue to grow. Homeowners and business owners will all be asked to both conserve water, while paying more for the municipal water they use.

The area above the pump vault needs to be left exposed. Fold the liner up in this area, and back-fill with dirt on all four sides. This locks the cubes into place. Continue with fill above the cubes. When finished, you should only see an area approximately 30-36 inches in diameter above the vault. Connect the pump controller to the pump using the 32-inch PVC nipple. Lower the pump down into the pump vault. The pump power cord plugs into the bottom of the pump controller. The controller will plug into a standard GFI protected outlet. Place the cover on the pump vault when finished. You can use a row of 6 to10-inch rocks to create a ring around the vault lid. This keeps the liner and the dirt behind it from washing into the vault. Small river rock can be used to cover the vault lid allowing easy access to the pump in the future.

Expect Government Regulations

Cities will begin to require rainwater harvesting, starting with commercial buildings. Forward-looking homebuilders offer rainwater-harvesting system options, but they will probably become a requirement soon. Rainwater harvesting addresses many problems. By capturing rainwater from roofs and parking areas, the burden on storm water systems can be significantly reduced, lessening the impact of sewage discharge into waterways. Harvested water can be recycled to water landscaping and flush toilets, reducing municipal water demand.

Plumb the downspout water into the system. Water coming from the filter can be plumbed into the system above the reservoir cubes. Since this is above the water level in the reservoir, no fittings are needed. Cut a hole approximately 2/3 the diameter of the pipe being used using (usually three inches) in the rubber liner and push the pipe thru the hole. If the reservoir collects water from a large area, and overflow may be required. This can be done via a natural low spot in the liner around the pump vault or by installing a bulkhead fitting in the liner and run a pipe to a nearby ditch or low area. Either way allows excess water out of the reservoir.

Water Harvesting Ordinances

Tucson, Arizona's city council passed an ordinance in 2009 requiring all new buildings to be plumbed for grey water capture and toilet flushing.

The US is now at the leading edge of communities writing code requiring mandatory grey water harvesting in new construction. Governments will begin to reward buildings with sustainable water systems. Progressive owners and their communities are already valuing water harvesting as part of sustainability features and LEED Certification. As the LEED program becomes more established, communities will begin to reward qualifying buildings with financial incentives. Commercial and residential buildings with sustainable water systems will have a higher resale value. The systems will become long-term assets for new projects. All of these make for good arguments that landscape contractors can use to encourage their clients to install water-harvesting systems.

There are a wide number or approaches to water harvesting, and a holistic approach will evaluate all sources of water as well as the best applications of harvested water. These can include multiple sources for rainwater, grey water and groundwater in a system. There are both active and passive approaches to harvesting. These include passive approaches like green roofs, vegetative swales and permeable pavement, as well as active approaches that include mechanically filtering and storing harvested water. Properly planned systems should use a combination of these approaches depending on the building's planned use, its features, size and physical location.

There are a host of manufacturers offering rainwater harvesting kits and supplies, look to page 63 for a listing. Now is the time for landscape contractors to act by encouraging their clients to build water harvesting and grey-water recycling systems into their homes and businesses.