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Case Studies
As part of an on-going program of testing and evaluation of ET controllers and how they affect the environments into which they are placed,
Aqua Conserve has completed the following studies. While water-use savings varied widely depending upon individual historical usage, the over-all
results demonstrated a net savings worth noting in each study. In each study the participants were selected by the participating agency.
One might conclude that a concentrated effort to distribute ET based controllers throughout a community would provide a significant reduction in the amount of water used for
landscape irrigation.
It is worth noting that there are many associated benefits to conserving water in this manner. The landscape itself benefits from irrigation more closely aligned to specific plant demands. Over-watering promotes weed growth, stimulates insect infestation, promotes soil compaction and prevents oxygen from reaching the root zones. Irrigating more closely to ET demands results in a healthier landscape.
Unfortunately, the irrigated landscape is not the only area affected. Run-off from over-watering sends harmful pollutants "downstream" to creeks, rivers and ultimately to the sea. These pollutants contaminate everything along the way and wreak havoc with the environment. Reducing watering to actual plant requirements reduces or eliminates wasteful run-off.
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U.S. Department of the Interior
 The Study revealed average water savings of up to 20,735 gallonsor 27.7CCF per account for the irrigation season from installing the ET controller and sensor. Of the devices, the ET controller had the strongest effect on reducing consumption, with the highest confidence level.
The potential impact of utilizing the ET controller and sensor are great. In Seattle and purveyor service areas there are about 315,000 single-family accounts and approximately 15-20% have in-ground automatic irrigation systems. Of the 315,000 customers, 5% or about 15,750 customers, have a total peak differential of over 44,880 gallons or 60 CCF. About 50% of those customers have an automatic irrigation system, If the estimated 7875 customers, who have the 44,880 gallon differential and an automatic irrigation system, installed the ET controller and sensor, the Saving Water Partnership could potentially save 1.2 million gallons per day or 3 billion gallons during the peak season.
Based upon reports from various pilot studies conducted with Aqua Conserve controllers, it appears significant water savings can be achieved for a relatively low initial cost and no ongoing costs. Significant savings have been reported even when the controllers were used without the temperature and rainfall sensors.
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City of Sonoma
 While the results for the City of Sonoma are much more wide-ranging than the results of Valley of the Moon, significant savings were obtained in both studies. Due to the wide variation between users in percent savings and the actual gallons used (example: one used 100% more water yet was one of the lowest in terms of water used) the final results are best expressed as total water saved as a percentage of the historic water use. The results are:
Total water use savings equalled 17% of historic use. Outdoor water use savings equaled 23%. Water saved during one season equalled 647,000 gal. Or 1.99 acre feet
Through the use of ET-based controllers, long term reduction in average residential landscape water usage can be achieved in terms of mitigating transmission supply system (shortages) during peak water demands.
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Valley of the Moon Water District
 Water saved on 10 accounts was 20.10% or 419,000 Gallons from June to November (totaling 6 Months).
Robert D. Freeland
Special Projects Coordinator
Total water use savings equalled 23% of historic use. Outdoor water use savings equalled 28%.
Overall, irrigation for the group of volunteers was reduced by 21.47%. Total savings during this first year was 1,424,000 gallons or 4.37 acre-feet.
Jim Reed Conservation Specialist
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Keesen Water Management
 Keesen Water Management designs irrigation systems and observes contractor installation to ensure lower maintenance and water costs. Our design philosophy is the result of many evaluations of existing systems.
Equipment that is high quality and performance, low in maintenance, long lasting and water conserving is the essential component of an acceptable irrigation system. Thus, selecting the right equipment for an irrigation project is vital to its long-term success.
ET group: Twenty nine participants were used for statistical evaluation.
Twenty two participants used less than the ET adjusted amount, one used more. Total gallons saved by group: 1,082,000
Average gallons saved per customer: 47,040
Average % below the ET adjusted number: 23%
Twenty two participants used less than ET adjusted amount, one used more. Total gallons saved by group: 760,00
Average gallons saved by each participant: 33,043
Average % below the ET adjusted number: 18%.
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