Sustainable Facilities Tool

Water Efficiency

Buildings are significant users of the Earth’s potable water supply.  The goal of a responsible building operator should be to encourage a smarter use of water, both inside and outside the facility.  Indoor water use reduction is typically achieved through efficient plumbing fixtures, fittings, appliances and process equipment used to heat and cool the building; outdoor water use reduction efforts should focus on water-wise landscaping.  By using less potable water, a building will also reduce the amount of energy needed to transport, treat, and redistribute that water, not to mention the cost savings associated with reduced potable water consumption.  Innovative solutions for water efficiency should include not only a reduction in the amount of potable water used, but also a reduction in the use of non-potable water where appropriate (for flushing toilets, watering the landscape, etc). 

Related Topics

Aerator

Aerators are flow restriction devices designed to limit the amount of water that comes out of a dispenser by mixing air into the water stream.  Aerators maintain steady pressure in the water flow and restrict the amount of water that is used for a given task.  

www.epa.gov/owm/water-efficiency/products/bathroom_sink_faucets.html

www.epa.gov/watersense

Automatic Fixture Sensors

Motion detectors can be installed on toilets, urinals and faucets to ensure that they automatically flush or turn on and turn off. They can be hard wired or they can run on batteries.  Note that automatic sensors for flush fixtures DO NOT improve water use – they simply ensure (or mean to ensure) that those fixtures are flushed.  In order to achieve water savings in toilets and urinals, low flow flush valves must also be installed.  Automatic sensors for flow fixtures on the other hand allow for a reduced duration of use, thereby reducing the amount of water used.

Blackwater

Blackwater is nonpotable water.  Exact definitions for what constitutes blackwater vary, but wastewater from toilets and urinals is always considered blackwater.  Water from food preparation areas, shower water, or bathtub water is sometimes considered blackwater, based on state and local laws.  Blackwater cannot be used in place of potable water and ideally would be processed separately from greywater.

Bleedoff/Blowdown

The intentional release of a portion of the recirculating water from a cooling tower is called Bleed off or Blowdown.  The recirculating water carries dissolved solids, which need to be removed because they can cause mineral buildup inside the system.

www.process-cooling.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000214768

www.sydneywater.com.au/publications/factsheets/SavingWaterBestPracticeGuidelinesCoolingTowers.pdf

Cooling Tower

A piece of building equipment which uses water to absorb heat from air-conditioning systems and regulate air temperature in a facility.

www1.eere.energy.gov/femp/program/operations_maintenance.html

www.process-cooling.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000214768

www.sydneywater.com.au/publications/factsheets/SavingWaterBestPracticeGuidelinesCoolingTowers.pdf

Drip Irrigation

Irrigation which is delivered through low pressure buried mains and submains.  From the submains, the water is delivered to the soil through a network of perforated tubes or emitters.  This high efficiency means of irrigation soaks the soil more efficiently and uses less water than traditional spray irrigation.

www.awwa.org/waterwiser/

www.muextension.missouri.edu/xplor/agguides/hort/g06912.htm

www.epa.gov/watersense/docs/water-efficient_landscaping_508.pdf

Dual-Flush

Dual-flush toilets are those that have two levels of flushing – a higher water use flush for solids and a lower water use one for liquids.  Dual-flush toilets have been in use for many years in countries like Australia, where water rationing is very common.  Dual-flush toilets are available in tank or flush valve types.  They can conserve significant amounts of water but require educating of building occupants for optimum water saving results.

Evapotranspiration Controllers (ET Controllers)

Evapotranspiration Controllers (ET Controllers) use soil sensors or weather reports to determine the appropriate amount of irrigation.  These devices, as well as rain sensors and other “smart” irrigation devices, help prevent water waste.

http://www.rainbird.com/landscape/products/controllers/etmanager.htm

Faucet

A faucet is a valve controlling the release of water.  Faucets can be fitted with flow restrictors or aerators to make them more water-efficient.

www.epa.gov/owm/water-efficiency/products/bathroom_sink_faucets.html

www.epa.gov/watersense

Flow fixtures

Flow fixtures include showerheads, bathroom faucets and kitchen faucets.

Flow Restrictor

Flow restrictors are devices designed to limit the amount of water that comes out of a dispenser.  They can be attached to faucets or inserted inside toilets, showers, or urinals.  They save water by limiting the amount of water provided for a given task.  

www.epa.gov/owm/water-efficiency/products/bathroom_sink_faucets.html

www.epa.gov/watersense

Flush fixtures

Flush fixtures include toilets and urinals.

Gallons per flush (GPF)

Gallons per flush (GPF) references the amount of water used per flush in flush fixtures, such as toilets and urinals.

Gallons per minute (GPM)

Gallons per minute (GPM) references the amount of water used by a flow fixture in a measured amount of time (one minute).

Greywater

Greywater is the wastewater from showers and sinks. Greywater can be captured and used in place of potable water to flush toilets or irrigate landscapes.  Greywater DOES NOT contain water from urinals or toilets, and usually does not have food preparation contaminants.

Hardscape

Hardscape is the inanimate elements of the building’s landscaping. For instance sidewalks, plazas, parking lots, and stone walls are all hardscape. Hardscape prevents water from being absorbed into the soil and can contribute to the heat island effect if it is dark in color.

Lavatory

Lavatory is a term meaning a basin for washing. Essentially, the hand washing basins located within a restroom are called lavatories. A low flow public lavatory sink is any that flows at .5 gpm or less.

Low Flow

Low flow plumbing fixtures use less water than their conventional counterparts by providing water at a lower rate.  Conventional fixtures typically base their water usage on the current Energy Policy Act (EPAct) which dictates the maximum allowable water usage per fixture type.  To significantly reduce water use, building managers can install fixtures that use less water than the baseline.  For instance, for commercial restroom sinks (also known as lavatories), the current baseline is 2.2 gallons per minute (gpm).  By installing 0.5 gpm aerators, the building can save 1.7 gallons per minute of run time.

www.epa.gov/watersense

www.epa.gov/owm/water-efficiency/products/bathroom_sink_faucets.html

Makeup Water

Water fed into a cooling tower system to replace water lost through evaporation, drift, bleed-off/blowdown, or other causes.

www.process-cooling.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000214768

www.sydneywater.com.au/publications/factsheets/SavingWaterBestPracticeGuidelinesCoolingTowers.pdf

Potable water

Potable water is drinkable water.  It flows from faucets and showerheads and is used in dishwashers, all of which require clean water for sanitary purposes.  Potable water is also used to flush toilets and irrigate landscapes – both are functions that could easily use greywater (recycled water) without compromising efficiency.  Where feasible, greywater should be used for these functions.

Process Water

Water used for industrial processes and building systems, such as cooling towers, boilers, and chillers. Greywater can sometimes be appropriately used as process water, conserving potable water.

Restroom Sink

Essentially, the hand washing basins located within a restroom are called restroom sinks.  A low flow public lavatory sink is any that flows at .5 gpm or less.

Showerhead

Showerheads control the speed and pressure of the water flowing from the pipe. There are many types of showerheads, including low flow, cascading, and handheld. A low flow showerhead is any that flows at or below 2.5 gallons per minute (gpm).

www.epa.gov/owm/water-efficiency/products/index.html

www.epa.gov/watersense

Toilet

There are conventional toilets and low-flow toilets.  Low-flow toilets save water with every use and save large quantities of water over time.  Low-flow toilets should use less than 1.6 gallons of water per flush (gpf).  An older conventional toilet designed to flush 3.5 gpf can successfully be retrofitted to use 1.6 gallons per flush (gpf). 

www.epa.gov/owm/water-efficiency/products/index.html

www.epa.gov/watersense

Urinal

Urinals can be conventional, low flow, or waterless.  A low flow urinal is any that uses less than 0.5 gallon per flush (gpf).

www.epa.gov/owm/water-efficiency/products/index.html

www.epa.gov/watersense

Water Closet

Water Closet is a term meaning flush toilets. There are conventional water closets and Low-flow water closets. Low flow water closets are preferred, as they save water on every use and save large quantities of water over prolonged use. A low flow water closet is one that uses less than 1.6 gallons per flush (gpf).

Water Use Baseline

The baseline is the plumbing code for a given flush or flow fixture.  It is the minimum level of efficiency prescribed by a governing body (usually UPC, EPA, or IPC).  

http://www.iapmo.org

http://www.iccsafe.org

Waterless/Dry/Nonwater Urinal

There are waterless toilets and waterless urinals, although waterless urinals are far more common.  Waterless urinals have no flush mechanism.  Liquid travels through a gel-filled cartridge which forms a seal to eliminate any odors.  Maintenance involves the replacement of the cartridge after a certain number of uses.  There are various types of waterless toilets including foam, incinerating and composting - all of which eliminate the need to flush drinkable water down the toilet.

Xeriscaping

A landscaping method that makes routine irrigation unnecessary.  The practice uses drought-adaptable, low-water, and native plants to decrease the amount of watering required.  Xeriscaping also uses soil amendments such as compost and mulch to reduce evaporation of water.

www.muextension.missouri.edu/xplor/agguides/hort/g06912.htm

www.epa.gov/watersense/docs/water-efficient_landscaping_508.pdf