Tuesday, January 19, 2010

Rain Water Harvesting and our Social Responsibility

Up to 70% our fresh domestic drinking water is consumed outside on the landscape.  By 9 a.m., after showering, using the bathroom, brushing our teeth and having a cup of coffee, each of us typically has used more than 30 gallons of water. After doing the dishes - 12 gallons per load - running the washing machine - 43 gallons per load - and watering the lawn - 10 gallons per minute - by the time we go to bed, we've used up to 150 gallons per person.

Nowhere is America's water crisis more evident than Lake Mead, just outside Las Vegas. The city has 2 million thirsty people - and gets 90 percent of its drinking water from the lake. 

Landscape designers have a social responsibility to reduce water use on the landscapes they design as well as educate clients on other options available to harvest water from other sources. 

Water harvesting will help save money on monthly water bills and reduce dependence on municipally-supplied water. A well-designed system will also decrease landscape maintenance needs.
Rain Water Harvesting Rooftop Collection Estimation:
  1 inch of rainfall on 1,500 sq.ft. roof could collect 900 gallons of water that can be used on trees, shrubs, and flowers.

Components of a Rainwater Harvesting System:
1. Catchment: the surface from which rainwater is captured.
2. Conveyance system: a means of moving the captured rainwater to where you want to store it. 
3. Means of Storage: locations where you can store the harvested rainwater.
4. Distribution System: rainwater stored in the ground or stored in tanks.
Water harvesting systems can be either active or passive, or a combination of both.

 A passive system directs harvested rainwater immediately into areas that are shaped to capture the water and allow it to percolate directly into the ground for use by plants.

A relatively shallow basin dug in the ground in order to collect rainwater, allows the water to sink into the soil. Basins are the most basic of all water collecting earthworks and will work in just about any situation.

Sculpting or contouring the landscape can capture all the rainwater that falls on a property in any given rain storm. Providing places for the water to be stored in the ground by creating berms, swales and basins, will yield quite a bit of water. Adding mulch on the top of the ground will increase the length of time the moisture remains in the soil.

 "If, as designers, we believe that design has the power to shape the future and that sustainability is something to strive for, how do we incorporate sustainability into our projects?" (APLD website)