End-Use Plumbing Fixtures
End-use fixtures-toilets, urinals, and aerators-offer managers of commercial, industrial, and institutional operations simple and straightforward opportunities to conserve water through retrofit or replacement of existing fixtures.
End-use plumbing fixtures found in today's buildings are typically grouped into three age segments: pre-1980, 1980 to 1994, and post-1994. Pre-1980 plumbing fixtures are generally considered highly to be inefficient. Fixtures installed from 1980 to 1994 are considered much more efficient that the pre-1980 ones. Finally, the highly efficient post-1994 fixtures with performance mandated by the federal Energy Policy Act of 1992 yield approximately 62 percent less water consumption than the pre-1980 fixtures and 39 percent less water use than 1980 to 1994 fixtures.
Toilets are among the best targets for cost effective water consumption reduction in residential-type applications such as hotels, representing about 35 percent of residential water use, and up to 70 percent of interior water use in a typical office building.
Toilets manufactured and installed before 1980 typically use between 5 and 7 gallons of water per flush. Between 1980 and 1994, toilets manufactured and installed in buildings use around 3.5 gallons per flush. The Energy Policy Act 1992 standards require toilets installed in new construction to use no more than 1.6 gallons per flush. Based on four flushes per day per person, post-1994 toilets can save about 16 gallons per day (roughly 70 percent) per capita over the pre-1980 toilets and 8 gallons per day (about 55 percent) per capita over fixtures installed between 1980 and 1994.
Some owners of early 1.6 gallons per flush toilets reported dissatisfaction. Many improvements have been made in toilet design to address these issues. The type of toilet should be chosen carefully for its level of use and application. Educating employees not to flush trash and of the importance of water efficiency will also help maintain user satisfaction. Actual customer satisfaction surveys conducted in Santa Rosa, California; Denver, Colorado; and New York City had a high customer satisfaction rate for customers installing ultra-low flush toilets.
Beyond the minimum federal standards for toilets, the U.S. Environmental Protection Agency (EPA) has developed a "WaterSense" label for high performing toilets. The EPA estimates that replacing old toilets with WaterSense labeled toilets could save approximately 2 billion gallons per day across the country. A WaterSense labeled high-efficiency toilet is a high-performing, water-efficient toilet that uses less than 1.3 gallons of water per flush. Toilets are certified by independent laboratory testing to meet rigorous criteria for both performance and efficiency.
Based on records of the age of facilities, facility managers can determine the efficiency of existing toilets and the benefits of retrofitting buildings with newer, more efficient models. Gravity flush toilets,consisting of a tank that drains using gravity upon flushing, are the most common of all toilets and are most likely to be found in medium-to-light use business applications. Water efficiency options for gravity flush toilets include improved maintenance, retrofit, or replacement. In general, however, full replacement provides greater water savings than retrofits.
Retrofit options of gravity flush systems are most effective on units that consume more than 3.5 gallons per flush. For toilets that consume 3.5 gallons per flush or less, retrofit options may hamper toilet performance or increase maintenance cost. Most retrofit options are available for less than $20 and include toilet dams, early closure flapper valves, and dual flush adapters. Toilet dams are flexible inserts placed in a toilet tank to keep 0.5 to 1.0 gallon out of each flush cycle. Early closure flapper valves replace the existing flush valve in the tank. These devices are adjustable to optimize performance and can save 0.5 to 2 gallons per flush. Finally, dual flush adapters allow users to use a standard flush for solids removal or a modified smaller flush for liquid and paper. Dual flush adapters can save between 0.6 to 1.2 gallons per flush.
Flush valve, or flushometer toilets use water line pressure to flush waste into the sanitary sewer system. They consist of a valve and a toilet bowl fixture. Most larger facilities use flush valve toilets, especially in higher-use areas. Valve inserts are available and can reduce flush volumes by 0.5 to 1.0 gallons per flush. Some of these devices consist of plastic orifices, perforated with holes in a wheel and spoke pattern. Others actually replace the existing valve mechanisms of a 5 gallons per flush unit with a 3.5 gallons per flush valve without changing the toilet bowl fixture. In general, as is the case with gravity toilets, full replacement of flush valve toilets provides greater water savings than retrofits.
Replacing older toilets with 1.6 gallons per flush models will provide the most water savings. Such replacements have the potential to offer a payback period of less than four years in residential-type applications, such as hotels and dormitories. Facilities may achieve quicker payback in these situations:
- If they experience high water and/or sewer costs;
- If they have a relatively high number of users per toilet; or
- If they currently use high water consuming (pre-1980) toilets.
Urinals use about one-half the water of toilets and have become significantly more efficient over time, and with the 1992 federal requirements. Up until the early 1990s, urinals generally used between 1.5 and 3 gallons per flush -- current standards require urinals to operate on one gallon per flush or less. Waterless urinals are also available that use a biodegradable liquid in place of water to provide flushing action. As with toilets, facility managers should look for opportunities to retrofit or swap out older, poorly performing urinals with newer, more efficient models.
Manufacturers that produce faucets and aerators meeting WaterSense efficiency and performance criteria can apply to have their products certified and earn the WaterSense label. WaterSense labeled faucets require that the maximum flow rate not exceed 1.5 gallons per minute at a pressure of 60 pounds per square inch at the inlet when water is flowing. Minimum flow rates shall not be less than 0.8 gallons per minute at a pressure of 20 pounds per square inch at the inlet when water is flowing. These standards, however, do not cover non-residential faucets and would only apply to smaller facilities where residential plumbing fixtures are used.
Larger non-residential restroom faucets are used almost exclusively for hand washing or simple rinsing, compared to lavatory faucets in homes and in other private bathrooms that face a myriad of uses. As a consequence, the maximum flow rate for public restroom and metering fixtures are set significantly lower than the flow rate for private lavatory faucets. A separate set of standards already apply to these types of fixtures. The ASME has established a maximum flow rate for public lavatory faucets at 0.5 gpm.
Retrofitting existing faucets with flow restrictors or aerators also generally provides a low-cost and effective water saving option. Assuming that a low volume aerator can reduce faucet flows from 4 gallons per minute to 2 gallons per minute, and that each individual uses the faucet 5 minutes per day, facility managers can save10 gallons per day per person. Aerators screw onto faucet heads and add air to the water flow while reducing water flow. They are available at common ratings of 0.5, 0.75, and 1.0 gallons per minute. Flow rates as low as 0.5 gallons per minute are adequate for hand wetting purposes in a bathroom setting. Aerators cost $5 to $10 and typically yield a payback within a few months.
Flow regulators can also be installed in hot and cold water feed lines to faucets. Common flow rate designs include 0.5, 0.75, 1.0, and 1.5 gallons per minute. Flow restrictors can be used where aerators cannot be used, or where there is faucet abuse, such as aerator removal. Flow restrictors can be installed for less than $25 and also yield a payback within months.
In addition to plumbing efficiency standards, new technologies have also been integrated into today's end-use fixtures that can increase their water use efficiency. Electronic controls, for example, can be installed with new plumbing fixtures or retrofitted on to many types of existing fixtures. Automated controls for faucets, toilets, and urinals help address occupants' concerns about disease transmission from contact with bathroom surfaces and fixtures, and they can reduce water consumption. These controls are rapidly gaining popularity in all types of commercial and institutional facilities. With toilets and urinals, some of the water savings may be attributable to reduced incidence of intentional multiple flushing- a common practice that contributes to excess water use.
Urinals with electronic sensors or with automatic, controlled flushing can conserve large amounts of water. At times when urinals experience heavy use, traffic can be detected and the urinals flushed periodically based on traffic rather than per person. This can significantly reduce water use (DOE Energy Efficiency and Renewable Energy).
As with urinals and toilets, faucets incorporating infrared motion sensors have been shown to reduce water usage by 70 percent over push-down, self-closing faucets. Depending on the faucet, a 10-second hand wash typical of an electronic unit will consume as little as 1-1/3 cups of water. Many commercial faucets can be retrofitted very quickly, requiring just 7 to 9 minutes per fixture. Some manufacturers estimate a payback period of less than 6 months when a conventional fixture is replaced with an electronic one. Replacement of conventional faucets with metering or self-closing faucets, however, is usually not cost effective due to high cost relative to the small amount of water savings potential.
Controls can also help increase water efficiency in kitchen applications. Aseptically operated faucet controls, for example, activate water flows by the use of either knee or foot pedals. During food preparation work in kitchen areas, faucets with hand operated controls can often be left on for convenience and/or ease of operation after preparation work is complete. Knee or foot pedals will not only reduce the quantity of water used during these periods, they also make faucet controls more convenient for staff and improve sanitary conditions for food preparation.
Pre-rinse Spray Valves
Dishwashing operations in commercial kitchens such as restaurant kitchens use over two thirds of an establishment’s water. Nearly one-half of this water may be used by pre-rinse spray valves, hand-held devices that uses spray water to remove food waste from dishes prior to cleaning. A great deal of energy is also used to heat the water used by spray valves. Like other end use fixtures, pre-rinse spray valve performance is based on its flow rate in gallons per minute (gpm). Since January 2006, new national standards require that all newly installed pre-rinse spray valves have a maximum flow rate of 1.6 gpm. Low-flow pre-rinse spray valves can save water while maintaining the same cleaning performance. Increased water savings also directly correlates with energy savings by reducing the amount of water that needs to be heated. Compared to a pre-rinse spray valve with twice the flow rate (3.20 gpm) used an average of 1.5 hours each day, a low-flow, a 1.6 gpm spray value can save nearly 52,000 gallons of water each year, as well as over $1,000 in annual energy costs for heating water (California Urban Water Conservation Council, 2007).
ReferencesCalifornia Urban Water Conservation Council (CUWCC). 2007. CEE Commercial Kitchens Initiative: Program Guidance on Pre-Rinse Spray Valves. CUWCC. Available at: www.cuwcc.org/sprayvalves.lasso.