Jul 21 2014Share

Rain Harvesters Reshape Yards To Save Storm Water

By Kathleen Ferris

So you sit on your back porch during a good monsoon storm and watch sheets of rain fall off the edge of the roof. Where you see rain, there is a small group of people who see your watershed. These people are Rain Harvesters.

Rain Harvesters don't allow rainwater to pool by their foundations, to scatter their gravel onto the sidewalk, or to rush into the streets and down storm drains. These homeowners have learned to keep rainwater on their property and direct it to their trees, plants and gardens.

Plants prefer rainwater, mostly because it does not contain the salt found in treated water. Rainwater also prevents salt from building in your soil, which help roots to grow larger and take up more water.

During a storm that produces 1 inch of rain, every 1,000 square feet of a slanted rooftop can produce up to 600 gallons of runoff. The Valley receives about 7 inches of rain a year. Rain Harvesters sometimes use elaborate gutters, pipes, underground drains, barrels and cisterns, but there are simpler techniques Valley homeowners can use to make the most out of every storm. These techniques require a little digging and letting gravity do the rest.

For those who want to begin retaining more rainwater on their property consider the Rain Harvester’s mantra: slow the rainwater, spread the rainwater and sink the rainwater. Here are a few ways to set you on the path of becoming a Rain Harvester, which will save water and money. Your plants will thank you by staying healthier.

  • Observe: Watch the water falling from your watershed and determine the directions of its flow in your yard. Look for the high and low spots where the rain settles or runs off. Some backyards slant toward the house, which can cause rain puddles near the foundation. If a home backs up to an alley, the yard will slant toward the alley. Most front yards slant toward the street where rainwater is swept into storm drains.
  • Look to nature: Swales are sloping channels or washes that Rain Harvesters use to direct rainwater away from a foundation, alley or street and toward a tree or garden. Sometimes they occur naturally in your yard, but most of the time homeowners must create swales. For example, homeowners can dig sloping swales in the ground just below the roofline and direct water toward a garden or tree. Lining swales with plants and rocks helps prevent erosion. Spreading 2 inches to 4 inches of crushed gravel in the bottom of swales will help retain moisture.
  • Lower your gardens: Sunken gardens make more sense in the desert than planting on mounds. Rain Harvesters plant in basins, which catch water long enough to allow it to sink deep into the ground. Garden and tree basins are typically dug about 8-inches deep. A basin under a mature tree should be as large as the circumference of the tree’s canopy, also called the tree’s drip line. If your garden is well established, collect and hold more rainwater by either building dirt and rock berms or digging basins around the existing gardens, plant groupings and trees.
  • Lose the slab: Use pervious surfaces for uncovered patio areas and walkways. For example, open paving with blocks or flagstone allows water to sink into the ground and into the roots of nearby trees. Depress the pervious areas to allow water to sink and spread. This can help keep water from pooling around a home’s foundation or porch.

This could be the last monsoon season you let water get away. For more information about rain harvesting visit AMWUA or the Watershed Management Group.

For 45 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit

To stay informed, sign up for the AMWUA blog

Sign Up Now