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BUILT GREEN, MAYBE WE SHOULD HAVE CALLED IT BUILT BETTER

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Reclaimed water systems: Can we reduce demand on treated water?

By: Joanne Herlihy, Dufford and Brown, member HBA Water Advisory Committee, with case studies by Dave Crane, Crane Real Estate, and Kristin Shewfelt, McStain Neighborhoods

There are two major types of water used for nonagricultural purposes, potable and nonpotable water. Potable water is defined as water that has been treated so that it may be used for drinking, personal or culinary purposes. The reality, however, is that a large percentage of the water being treated to potable water standards in costly water treatment facilities is not used for these explicit purposes. which represents an extremely inefficient use of potable water.

Nonpotable water is water that is not treated to a level that is safe to drink, but is treated under Department of Public Health and Environment standards to a level that is safe enough for other uses. The article and case studies below explore the use of alternative water systems, including reclaimed water and raw water irrigation systems. which can play a significant role in reducing the need for potable water supplies.

Reclaimed water systems
By Joanne Herlihy

Reclaimed water (also referred to as recycled water) is wastewater effluent from homes and businesses that has been filtered and disinfected at a wastewater treatment facility to meet Colorado Department of Public Health and Environment standards. Once treated to these standards, it can then be used for another purpose usually industrial and irrigation, but also in other capacities such as wetland restoration and fire protection. Using reclaimed water for irrigation and nonpotable industrial uses reduces demands on valuable surface water and groundwater used for drinking water.

Reclaimed water is delivered from the treatment facility to customers through a separate system of purple pipes. To

Using reclaimed water for irrigation and nonpotable industrial uses reduces demands on valuable surface water and groundwater used for drinking water.

eliminate any risks because of unintended connections between reclaimed water and a municipality's potable or drinking water systems, there are no direct cross connections or interconnections between the two systems. In sonic instances, the systems are designed with air gap connections to allow potable water to be put into the reclaimed system to respond to emergencies. but the air gap makes it impossible to send reclaimed water to the drinking water system. As an added precaution, however. there are utilities that do not allow customers to switch back and forth between treated and untreated systems. Reclaimed water pipes are laid at a depth lower than drinking water pipes so that even in the case of an underground leak. the reclaimed water would flow away from the drinking water pipes. While reclaimed water is not intended for drinking, it is treated to a safer standard than water at most beaches and so is safe for adults. children, pets and wildlife that may come into incidental contact with it.

The use of reclaimed water for nonpotable purposes has been a widely accepted practice around the world for decades. A number of states, such as Florida. California and Texas, have or are in the process of building reclaimed water facilities and Colorado communities arc joining those ranks. The city of Westminster. for example, is already operating a reclaimed water facility that at full build-out is anticipated to recover over 2,700 acre-feet from wastewater for local irrigation uses. This represents savings of potable water equal to the amount needed to serve over 2.500 single-family homes for a year. Westminster's reclaimed water customers include Westminster city property, business parks and several golf courses, including Legacy Ridge, Heritage, the Ranch County Club and Golf Course and Hyland Hills. At an estimated cost of $140 million dollars, Denver Water is currently in the process

Case study in the use of reclaimed water systems: Irvine (Calif.) Ranch Water District

By Dave Crane

The Irvine Ranch Water District (IRWD), located in Irvine, Calif., is one of the pioneers in water reclamation through a dual piping system. IRWD operates a tertiary treatment plant and a totally separate distribution system consisting of 245 miles of pipeline, eight storage reservoirs and 12 pump stations for reclaimed water. Reclaimed water now makes up 20 percent of IRWD's total water supply and provides irrigation for 80 percent of all commercial and community landscapes, including parks, schools, golf courses and open space. Over 5,650 acres of landscaping are irrigated with reclaimed water. A few estate-sized residential lots also use the water for irrigation and most water features are filled with reclaimed water. Reclaimed water has also been used in industrial applications. A carpet mill estimates they save from 500.000 to 1 million gallons per day of potable water by using reclaimed water in their production process.

In addition to outside use, IRWD has received health department permits for interior use of its reclaimed water. Reclaimed water is currently used for toilet flushing in the district's offices as well as several high-rise office buildings. Potable, or drinking, water demand has dropped by as much as 75 percent in these buildings due to reclaimed water use.

of building a water recycling system (treatment facility and distribution system) that. upon completion, will he able to treat and deliver up to 17.440 acre-feet of water per year, or the equivalent of supply' to about 34.900 homes. The Denver Water project is planned in three phases with the first phase to be completed in early 2004 and the final phase in 2013. Denver Water's reclaimed water customers will include Xcel Energy's Cherokee Power Plant, Park Hill Golf Course, Stapleton, the Rocky Mountain Arsenal, DIA. Denver parks currently served by the City Ditch, and the Lowry Redevelopment area.

Limitations, both legal and financial, exist on the amount of reclaimed water that can be made available for delivery. Legally, in Colorado, the amount of water available for use is controlled by terms and conditions of' the water rights owned by a municipality. Generally. use of a water right is limited to the consumable portion of that water: i.e., the amount of water consumed after a single use is made of the water. The nonconsumed portion is not available for use and must be returned to the source to be made available to the next water rights holder.

A simple example is residential use of water. Of potable water delivered to a home and used for various domestic purposes. generally 90-95 percent of that water is returned to the municipal system as wastewater. If the underlying water right is not decreed to he fully consumable. then after the residential use of the water, the municipality must return wastewater, after treatment, to the river for use by other water rights holders.

In other words, though a municipality

Case study in the use of raw water irrigation systems: McStain Neighborhoods At High Plains Village, Loveland

By Kristin Shewfelt

At its High Plains Village community in Loveland. McStain currently has pumping rights to flouts Reservoir for the northern portion of its 300-acre parcel, referred to as Millennium. All the common areas and open space in the Millennium parcel, with a projected start date of mid-2005, will he on a separate raw water (untreated) irrigation system. The southern parcel (RMV II subdivision) is currently retrofitted to accommodate raw water irrigation in the future. The use of a raw water system is tied to the securing of water rights for the parcel and the extension of infrastructure from the Millennium parcel.

McStain has been able to calculate significant water savings through the use 01' raw water irrigation. This includes the refund of in-lieu water fees already paid for potable water supplies previously dedicated for open space and common areas as well as a reduction in water costs for ongoing irrigation.

may generate a large amount of waste-water, the amount of that wastewater that can he reclaimed and made available for subsequent uses, such as industrial and irrigation, is limited to the amount of fully consumable water available to that municipality.

Financially, a large part of the cost of a reclaimed water system is the delivery system. Because reclaimed water must be delivered in separate pipelines, pipelines and pumping systems must be installed for delivery of the reclaimed water from the treatment plant to customers. These costs can be significant where pipeline must be laid through an already developed area.

Neither Westminster nor Denver has any near-term plan to supply reclaimed water to individual residences for irrigation. This is due in large part to the limitation on the amount of reclaimed water that can be made available and in part due to the cost of installing a delivery system to small individual users.

2008 Built Green Colorado

Home Builders Association of Metro Denver, 9033 E. Easter Place, Suite 200, Centennial, CO 80112
(303) 778-1400 fax: (303) 733-9440  info@builtgreen.org

Last Updated: 04/10/2004