Water Conservation

Case Studies

Following are some interesting case studies from the Southwest Florida Water Management District. Although the examples are from Florida, they apply universally.

After a comprehensive water use evaluation, a St. Petersburg, Florida, manufacturer was given the following recommendations for water conservation:

Bathroom Retrofits (potential savings of 2 million gallons of water and $11,700 each year)

• Replacing toilets with new 1.6 gallon per flush models
• Retrofitting urinals with low-volume valves
• Installing lavatory aerators that allow a flow of 2.0 gallons per minute

Cooling Adjustments (potential savings of 1.7 million gallons of water and $9,400 each year)

• Installation of a flow control device
• Adjustment of conductivity up to a higher level that could still provide reliable service while using less water

Recirculation System (potential savings of 1.7 million gallons of water and $9,400 each year)

• Reduction in water loss through the use of an existing storage tank

An office building in St. Petersburg, Florida, was given the following recommendations for water conservation:

Bathroom Retrofits (potential savings of 0.2 million gallons of water and $744 each year)

• Replacing flushometer valves to reduce the flow
• Installing lavatory aerators that allow water flow at a rate of 2.0 gallons per minute

Cooling Adjustments (potential savings of 1.5 million gallons of water and $6,874 each year)

• Adjustment of conductivity up to a higher level that could still provide reliable service while using less water

Water-Efficient Fixtures and Appliances

In 1992, federal legislation was passed that requires U.S. plumbing manufacturers and importers to adhere to the following water-efficiency standards:

• Showerheads: 2.5 gallons per minute
• Faucets: 2.5 gallons per minute
• Toilets: 1.6 gallons per flush

Most toilets made in the 1980s used 3.5 gallons of water per flush, while earlier models used 5 gallons or more. Older showerheads used as much as 4 to 12 gallons per minute. The new standards mean that an average household could reduce per capita indoor water use from over 70 gallons per day to approximately 50 gallons per day. New technologies can reduce water usage to 25 gallons per day without sacrificing performance.

Some newer fixtures include the following:

• The laminar flow faucet conserves water by getting objects and hands wet faster and by allowing lower flows to feel like higher flows. It produces dozens of very close parallel streams of water instead of just one stream.
• Low flow faucets use aerators that add air to the water stream to make a small stream feel bigger.
• Faucets that use a pedal on the floor to turn on the water. When the pedal is not being pressed, the water turns off. A handy device that saves water during washing, shaving, and brushing teeth.
• Dual flush toilets have two buttons to release water. They use approximately 1.6 gallons of water for a full flush and 0.8 gallons for liquids only.
• Showerheads that use only 1.5 gallons per minute. This showerhead reduces water use and energy by approximately 40% compared to a 2.5 gallon per minute model, and 70% compared to older 5 gallon per minute models.

Irrigation Systems

The amount of water a plant needs depends on the plant type, plant size, and weather conditions. A good rule of thumb, according to Clemson University’s Extension Service, is to plan to irrigate one inch of water per week. The one inch refers to the amount of water that actually enters the soil. Use this amount for a few weeks. Then, adjust the amount as needed. If the ground stays very wet, lower the irrigation amount. If plants appear stressed, use more water. Remember that plant growth and weather conditions change, so adjusting the irrigation amount is an ongoing job.

Other considerations for adjusting irrigation amounts follow:

• Evaporation: a typical sprinkler operated at noon on a hot, windy, dry day in summer can lose 30% or more of the water to evaporation.
• Runoff: water is wasted because it is applied too quickly and the soil can’t absorb it. Sandy soils accept water more quickly than clay soils and dry soil accepts water more quickly than moist soil.
• Frequency: irrigate as seldom as possible. Irrigating once deeply is better than irrigating twice or three times shallowly.
• Municipal Water Systems: to save money, install an irrigation water meter. Sewer usage usually involves no fees since the water is not returned to the municipal sewer system.
• Sprinkler Heads: should be placed so that their stream of water actually touches the next sprinkler (or is within one to two feet of touching). The overlap ensures good, uniform coverage.
• Timers: operate a sprinkler automatically, reducing the possibilities of overwatering and the number of staff hours devoted to the task.

Xeriscaping

The word xeriscaping comes from the Greek word xeros, which means dry. It is a term used for water-conserving landscaping. Xeriscaping is a practice that uses slow-growing, drought-tolerant plants to conserve water and reduce yard trimmings. Xeriscaping varies from region to region. Plants that are appropriate in one climate may not work well in another. Landscapes need to be planned to be compatible with locally available resources, including water, soil types, and sunlight.

A traditional landscape can be transitioned to a more resource-efficient landscape, but that requires planning. Proper design and plant selection can reduce the amount of waste a landscape generates through maintenance. Over time, however, time and money can be saved. Xeriscaping generally requires less fertilizer and fewer pest control measures, which results in reduced impact on air and water quality.

Since the 1980s, the concept has been adopted in areas in the desert Southwest and the states of California and Florida as well as other areas. In Albuquerque, New Mexico, residents can receive up to an $800 rebate on their water bill for xeriscaping, while businesses can receive up to a $5,000 rebate.

Submetering

Submetering water usage has been shown to strongly promote water conservation. In properties that are submetered or otherwise billed, tenants generally consume 18% to 39% less water than in properties that include one shared water meter. Simply put, just as billing tenants individually for the electricity they use significantly reduces energy usage, submetering reduces water usage.

Reducing water usage clearly is good for properties, residents, and the environment. When water usage is included as part of the rent, it can be a significant percentage of operating costs. In contrast, water submetering can control costs and lead to lower rents for multifamily, office, and industrial space. So can the Ratio Utility Billing System (RUBS), which bases its billing on the size of a unit or the number of residents occupying it and does not require additional equipment or metering services.

New technologies are available that use wireless systems to read meters. An automated meter reading (AMR) system increases the frequency and accuracy of system-wide reporting and does not need a field technician. It also allows companies to give time-of-day-based conservation incentive plans for their customers, simplifying and reducing the cost of reading meters and the cost of utilities to the end user.

A network meter reading (NMR) system requires some type of communications device, which is typically retrofitted to a utility’s existing meters. This device sends signals through the system’s local area network to a pole-top device, which begins to process the information from the meter. For example, this device will route alarm signals back to the system’s head end with a higher priority than it sends back standard meter reads.