Water Conservation Strategies for Commercial Landscaping

Increasing demand

Metro Atlanta water use• Single Family residential water consumption = 191 MGD

to 280 MGD (149 GPCD)• Outdoor water consumption = 38 MGD to 56 MGD

Regional Limitations to Water Resources• 98% of Atlanta’s water needs are supplied by surface water sources

• 80% of surface water is supplied by the Chattahoochee• Atlanta’s location at the headwaters limits the supply• Bedrock limits groundwater sources• Increasing demand: +1,000,000 residents in 10 years SOURCE: ARC

3. Minimize water demand

4. Meet demand with non-potable water

3. Deliver water efficiently

3 Steps for Outdoor Water Conservation

Minimize Water DemandUse regionally native or Drought-tolerant non-invasive species

Minimize the use of turf

Keep stormwater runoff on-site to nourish the landscape

Minimize Water Demand

Protect and restore healthy soil.

Minimize Water Demand

Meet Demand with Non-potable WaterBenefits of Rainwater Harvesting• Rainwater is free – helps to reduce utility bills• Can eliminate costly infrastructure• Not subject to watering restrictions• Eliminates the need for water softeners if used indoors• Rainwater is the most pure water (chemical free) to use on

plants, vegetables, etc.• Reduces runoff to storm drains• Entire system costs range from $.75/gallon to $2/gallon

with a payback period of less than ten years (NCSU).• Important part of an overall strategy to conserve water

resources

History of Rainwater Harvesting• Rainwater harvesting is an ancient technique dating back as far

as 4,000 years ago.• Still widespread in India, Australia, the Caribbean and other

regions with poor public infrastructure and dry climates.• Enjoying a resurgence in the US, partly due to superior water

quality and partly due to the desire to reduce consumption – an estimated 100,000 systems are in use.

• Currently, there are no national standards governing rainwater harvesting.

• However, rainwater harvesting is currently mandated for new construction in Bermuda, US Virgin Islands and other Caribbean islands.

• Incentives are in place to offset costs in Texas (maybe in the southeast soon?)

• Simplest systems are land-based and may consist of earthen berms and reservoirs.

• More complex systems take many forms…

Meet Demand with Non-potable Water

Memorial Garden @ the SLC (Photo courtesy of Kevin Kirsche, University Architects)

Components of A Rainwater Harvesting System

Meet Demand with Non-potable Water

The supply (amount that can be collected and stored) must equal or exceed the demand

(anticipated amount that will be used)

Water Balance and System Sizing

Meet Demand with Non-potable Water

Assumptions: demand of 3,000 gal/mo; collection efficiency of 85%; .62 gal/S.F. of catchment per inch of rain; 10,000 gallon storage capacity; 1,000 gallon starting volume; Dallas, Texas location

System Sizing Example

Meet Demand with Non-potable Water

Drip Irrigation

Deliver Water EfficientlyAvoid waste through overspray and evaporation. Deliver directly to the plant.

Irrigation ZonesWeatherTrak Controller

Apply water only when and where it is needed.

Rain Sensor

Soil Moisture Sensor

Deliver Water Efficiently

The Lady Bird Johnson Wildflower Research Center – Austin, Texas

• 70,000 gallons of total cistern storage capacity

• 17,000 S.F. of catchment area

• Broken up into several catchments and cisterns throughout the site

• Aesthetic / experiential system created by conveying water through aqueducts to exposed above-ground cisterns

• Local materials create a sense of place

• Used solely for irrigation

The Lady Bird Johnson Wildflower Research Center – Austin, Texas

The Southface Energy Institute – Atlanta, Georgia

• 1,750 gallon rooftop cistern for toilet flushing and mechanical demands

• Below-grade cistern stores site runoff for non-potable uses (irrigation)

• Collector area should yield approximately 42,000 gallons per average year

• Combined with efficient interior fixtures, this results in a total water savings of 150,000 gallons per year when compared to a comparable

conventional building – a 74% reduction.

Resources: http://www.twdb.state.tx.us/assistance/conservation/alternative_technologies/rainwater_harvesting/rain.asp