Commercial Restroom Water Audits
Toilets (Water Closets)
For a full discussion of toilet fixtures (residential and commercial), including descriptions of the types of fixtures and reports on water savings with high-efficiency toilets (HETs), go here.
Water savings can be achieved by replacing older model toilets using 3.5 gpf (13 Lpf) or greater with ne
w ULFTs (1.6 gpf - 6.0 Lpf), HETs (1.28 gpf - 4.8 Lpf). The frequency of toilet flushes per toilet is highly variable from facility to facility. It is reasonable to assume an average of 2 to 4 flushes per person per 8 hour shift for workers; and 1 to 2 flushes per visitor. When conducting benefit/cost analyses, it is important to separate the calculations for women’s toilets versus men's toilets for two reasons: (1) the ratio of men's room toilets per male (worker and customer) is usually different from the ratio of women's room toilets per female worker and customer; (2) men wi
ll most often use urinals (when available) rather than toilets. Every facility is unique in its flushing frequency. While it is reasonable to use average toilet usage estimates for program planning, performing toilet retrofit projections on individual facilities requires calculations based on unique site data. A sample calculation might be:
- 364 days open per year
- 30 male workers/shifts, 10 female workers/shifts
- 200 male customers/day, 50 female customers/day
- 8 male toilets, 8 urinals
- 8 female toilets
Male Toilet Flush Quantities:
30 males x 364 x 0.5 toilet flushes/day = 5,460 toilet flushes/year
200 males x 364 x 0.25 toilet flushes/day = 18,200 toilet flushes/year
23,660 flushes / 8 toilets = 2,975 flushes/year/male toilet
Male Urinal Flush Quantities:
30 males x 364 x 2.5 urinal flushes/day = 27,300 urinal flushes/year
200 males x 364 x 1.75 urinal flushes/day = 127,400 urinal flushes/year
154,700 flushes / 8 urinals = 19,300 urinal flushes/year/urinal
Female Toilet Flush Quantities:
10 females x 364 x 3 toilet flushes/day = 10,920 toilet flushes/year
50 females x 364 x 2 toilet flushes/day = 36,400 toilet flushes/year
47,320 flushes / 8 toilets = 5,915 flushes/year/female toilet
Conclusion: This example shows replacing male urinals will likely garner the greatest savings and replacing female toilets offers better return on investment than male toilets.
It is important to note that water consumption by toilets and urinals should NOT be based upon the number of fixtures installed in the building, but rather upon personnel occupancy of the building.
The predominate types of toilets in CII restrooms are the flushometer valve/bowl combination or the pressure-assist tank-type toilet, although gravity-tank toilets are used frequently in light commercial applications. In most instances, both the bowl and the flush valve of the flushometer valve toilets must be replaced to assure water savings and adequate flushing performance. The cost to replace a flushometer type toilet usually ranges from $250 to $400, depending on whether or not the valve will be replaced. Wall-mounted flushometer valve toilets are the most commonly found in new buildings, while floor mounted toilets are more common in older buildings.
As with all toilets in the commercial sector, there are several best management practice considerations:
- No less frequently than annually, inspect diaphragm or piston valves in flushometer-valve-type toilets, and replace any worn parts. To determine if the valve is in need of replacement, determine the time it takes to complete a flush cycle. A properly functioning flush valve should not have a flush cycle longer than four seconds.
- If replacing valve inserts, confirm that the replacements are consistent with the valve manufacturer’s specifications, including the rated flush volume. If replacing the entire valve, ensure it has a rated flush volume consistent with manufacturer specifications for the existing bowl, including the rated flush volume.
- Periodically check to ensure the control stop (which regulates the flow of water from the inlet pipe to the flushometer valve and is necessary for shutting off the flow of water during maintenance and replacement of the bowl or valve) is set to a fully open position during normal operation.
- Upon installation of a flushometer toilet, adjust the flush volume in accordance with manufacturer's instructions to ensure optimum operation for the facility's specific conditions. Periodically inspect the flush volume adjustment screw to ensure the flush volume setting has not been modified from the original settings; if it has, it could change the water use and performance of the product.
- Ensure that the line pressure serving the fixture meets the minimum requirements of the fixture manufacturer (minimums are commonly specified as 35 psi).
- If installed, check and adjust automatic sensors to ensure proper settings and operation to avoid double or phantom flushing. Alternatively, remove sensor systems and replace with manually activated flush valves, which are shown to significantly reduce water consumption at the toilet. There is no evidence the sensor-activated flush valves save water. In fact, studies in office buildings and other public venues show that water use increases when manual valves are replaced with sensor-activated valves.
- If installing dual-flush toilets, it is wise to post instructions for the toilet users.
- Excessive paper (toilet paper, disposable seat covers and paper towels) are the most common causes of clogged toilets. Consider alternate methods of hygiene (sanitizers, continuous roll seat cover dispensers, hot air hand dryers, etc.), and select new toilets models that exceed 500 grams (1.1 pounds) in MaP Testing.
- Flushing performance is very important for success. Refer the MaP testing before selecting new toilets.
For a full discussion of urinal fixtures, including descriptions of the various types of fixtures, go here.
Many urinal fixtures being installed today are high-efficiency urinals (HEUs). An HEU is defined as a fixture that flushes at 0.5-gallons or less. This definition includes 0.5-gpf urinals and non-water urinals as well as the one-quart (0.25 gpf) and one-pint (0.125 gpf) urinals currently available in the marketplace from several manufacturers. For a listing of all available HEUs, go here.
The water savings benefit of replacing urinals is highly dependant on frequency of use and the type of replacement proposed. Frequency of use is determined by calculating the quantity of male 8-hour shifts, and the average urinal flush per man per 8-hour shift (usually 2 to 4). Depending on the nature of the CII facility, visitors may add significantly to the daily flush counts.
Many options exist for urinal replacements, from simply replacing the flush valve to reduce flow, to replacing the entire fixture with an HEU. All options vary in the costs and benefits. In many cases, marginal water savings can be achieved by simply retrofitting the urinal flushometer valve to a lower gpf diaphragm, though many older urinals will not function properly at these reduced flows. Unfortunately, this type of valve-only retrofit can be easily and mistakenly reverted back to the higher flush volume during routine maintenance; thus, we seldom recommend this “partial” measure. Much consideration is needed to determine the best retrofit or replacement for any given restroom. To assure water savings are sustained over time, the best strategy is to replace the entire urinal and flush valve with an HEU.
As with all urinals in the non-residential sector, there are several best management practice considerations:
- No less frequently than annually, inspect the flushometer diaphragm or piston valves, and replace any worn parts. If replacing valve inserts, verify that the replacements are consistent with the valve manufacturer’s specifications, including the rated flush volume. If replacing the entire valve, ensure it has a rated flush volume consistent with manufacturer specifications for the urinal fixture itself. That is, the urinal fixture should be designed to function at the lower flush volume of the high-efficiency valve.
- Annually check and adjust automatic sensors, if installed, to ensure they are operating properly to avoid double or phantom flushing. Sensor-activated flush mechanisms often result in more frequent urinal flushing than manual flush valves. There is no evidence the sensors valves save water. In fact, studies in office buildings and other public venues show that water use increases when manual valves are replaced with sensor-activated valves.
- Flushing urinals equipped with automatic flush sensors will often have an override switch, allowing maintenance personnel to activate the flush manually. Activating the override switch may release a larger volume of water than is typical for the standard flush. Train custodial and maintenance personnel on how to clean and maintain urinals with automatic flush sensors to ensure that the urinal is returned to its intended flush volume after maintenance operations are completed.
- Train users to report continuously flushing, leaking, or otherwise improperly operating urinals to the appropriate management or maintenance personnel.
- Non-water urinals are considered compliant by most, but not all plumbing code authorities. The Uniform Plumbing Code and the International Plumbing code allow the urinals, but some local cities and counties have not yet approved the devices. It is wise to contact the local authority having jurisdiction before installing non-water urinals.
Flow rates for faucets in public (commercial) lavatories can reasonably be reduced to 0.5 gpm (1.9 Lpm) or lower. (The current national standard and all of the major model plumbing codes in the U.S. call for a maximum flow rate in non-residential lavatory faucet installations of 0.5 gpm (1.9 Lpm.) Projected savings are usually based on usage frequencies similar to toilet and urinal use. Flow durations are often estimated to be 5 to 30 seconds per use. Retrofitting aerators on the faucets is the most common and least expensive strategy to achieve the 0.5 gpm (1.0 Lpm) rate. The water savings are small when compared to replacing toilets, but the cost of retrofit is minor, usually less than $5.00 per faucet.
Some lavatory sinks are fitted with metering faucets (automatically shut-off after a preset time span) or negative shut-off valves (user must continue to exert pressure on valve handle to maintain water flow). These types of valves save water and deter flooding the lavatories. Metering faucets for public applications are subject to the same codes and standards as other faucets, all of which set the maximum water use at 0.25 gallons per cycle (.94 L). That is, the “on-off” cycle (or time during which the faucet is on) cannot result in a total volume in excess of 0.25 gallons (.94 L) of water. It is important to note that metering faucets are NOT subject to a maximum flow rate. Hence, if a cycle is 15 seconds, that then means the flow rate can be as high as 1.0 gpm (3.8 Lpm). A 20% reduction (to a total volume per cycle of 0.2 gallons – 0.76 litres) may be achieved by shortening the cycle to 12 seconds at 1.0 gpm (3.8 Lpm), leaving sufficient water for washing one's hands.
Sensor-activated faucets are another option for the commercial rest room. However, there is no independent, scientific evidence that sensor-activated faucets save water. To the contrary, recent studies have provided valid evidence that sensor faucets use much greater water than manually activated valves. Sensor activated valves provide user convenience, but are now known to be wasters of water.
For a full discussion of showerheads, including descriptions of the types of showerheads and the marketplace, go here.
Some CII facilities include showers. The Energy Policy Act of 1995 set maximum showerhead flow rates rate at 2.5 gallons per minute (gpm) (9.5 Lpm). Despite this federal mandate, some showers can still be found flowing in excess of 5 GPM (19 Lpm). Depending on frequency of use, replacing showerheads in the locker rooms might offer significant water savings.
New, well-designed 2.0 to 2.5 gpm (7.6 to 9.5 Lpm) showerheads offer a satisfying and effective shower experience for users. There are some models of showerheads that flow significantly less than 2.0 gpm and also have high levels of consumer satisfaction, but these are not recommended due to safety concerns. As showerhead flow rates have decreased, the incidents of accidental scalding have increased, caused by the loss of thermal buffering in water volume when supply water temperature or line pressure changes suddenly. Thermostatic mixing valves prevent this problem, and are now required by most plumbing codes. To date, thermostatic mixing valves are only tested and certified for flows of 2.5 gpm (9.5 Lpm) or greater. Installing showerheads with flow rates below 2.5 gpm (9.5 Lpm) is not recommended until thermostatic mixing valve requirements are flow rate-matched to accommodate lower flows.
Water savings projections can be easily estimated by measuring the flow rates of the pre-existing showerheads, estimating the usage rate, and calculating the water use differential. A facility that has 20 showers taken per day, using 4 gpm showerheads, could save 9,000 gallons per month (34 m3) by converting to 2.5 gpm (9.5 Lpm) showerheads. This equates to more than 100,000 gallons saved per year (380 m3).
Building managers are sensitive to user satisfaction, especially private membership clubs, and shower quality can evoke strong negative reactions.
Therefore, when installing new showerheads or replacing older, inefficient showerheads, choose WaterSense-labeled models. WaterSense-labeled showerheads (www.epa.gov/watersense/products) are designed to consume 2.0 gpm or less, 20 percent more water-efficient than standard showerheads. In addition, WaterSense-labeled showerheads are independently certified to meet or exceed minimum performance requirements for spray coverage and intensity (force). WaterSense has established maximum and minimum flow rates at three different building line pressures: 80, 45, and 20 psi (the upper, mid, and lower range of potential household pressures)1. In addition to the pressure and flow rate requirements, WaterSense created criteria for spray coverage and intensity to ensure product performance under conditions of lower flow rates.2 WaterSense-labeled showerheads are independently tested and certified to meet these criteria before they receive the label.
1The minimum flow rate is defined as a percent deviation from the maximum flow rate of the showerhead. For instance, the showerhead’s flow rate at 20 psi cannot be less than 60 percent of the maximum flow rate (i.e., a showerhead with a maximum rated flow rate of 2.0 gpm will not flow at less than 1.2 gpm even in a living unit with very low water pressure).
2WaterSense requires that minimum spray force shall not be less than 2.0 ounces (0.56 newtons [N]) at a pressure of 20 ± 1 psi (140 ± 7 kPa) at the inlet when water is flowing. Also, the total combined maximum volume of water collected in the 2- and 4-inch annular rings shall not be less than 25 percent or more than 75 percent of the total volume of water collected.