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Residential Shower and Bath Introduction
The question is often asked: What uses more water, a shower or a bath? The answer has been and always will be, “It all depends …… ”.
Showers are typically the third largest water use in the residential setting after toilets and clothes washers. According to the AWWA Residential End Uses of Water study, the average American shower uses 17.2 gallons (65.1 L) (and lasts for 8.2 minutes at at average flow rate of 2.1 gpm (7.92 Lpm) ((Mayer, et. al, 1999).
Water Usage and Bathing Method
Showers
Two factors influence the water usage of a shower: flow rate and duration. Current national energy policy act (EPAct) standards mandate that all showerheads manufactured in the U.S. have a maximum flow rate of 2.5 gpm (9.5 Lpm). There are certainly some showerheads and shower systems that exceed this flow rate, and others that use 1.5 gpm or less (5.7 Lpm).
Before 1980, many showerheads exceeded 5 GPM (18.9 LPM). Energy conservation initiatives enacted regulations to limit shower flows to reduce hot water usage and consequently the natural gas and electricty used to heat water. In the mid-1980s, some states restricted flows to 3.5 GPM (13.2 LPM), and later reduced further to 3.0 GPM (11.4 LPM). The Federal Energy Policy Act set a nationwide regulation to limit showerheads to a maximum flow of 2.5 GPM (9.5 LPM) in the mid-1990s, following California’s mandate in 1992.
The duration of the shower has equal effect on water usage. A 20 minute shower will use twice as much water as a 10 minute shower taken at the same flow rate. Many have hypothesized reducing flow rates of shower heads might cause users to take much longer showers. Scientific studies that monitored thousands of homes across the nation have proven the flow rates have little influence on the duration of the shower. In fact, users of 2.5 GPM (9.5 LPM) shower heads increase the duration of the shower less than 1 minute, compared to those showering with 3.5 GPM (13.2 LPM) shower heads.
Learn more about showerhead flow restrictors and timer devices here:
Shower Flow Restrictors Introduction
Shower Timers Introduction
Baths
The size of the bathtub, and the level the user fills the tub also affects water use. With the exception of whirlpool and jetted tubs, the size of standard bathtubs in North America has generally decreased over time. The typical modern (non-jetted) bathtub today will hold approximately 25 to 45 gallons (94.6 L to 170.3 L) of water depending upon the fill level. A person who only fills the tub half-way will consume approximately 20 gallons (75.7 L). Bathers that fill the tub up to (or exceeding) the owerflow valve will use 40 to 50 gallons (151.4 L to 189.2 L).
Showers vs. Baths
The response to the opening question can best be illustrated in the following chart.
* Shower spa consumption includes the water usage of the soap/shampoo shower required after the spa event
As the chart illustrates, a person that takes long showers or uses a high flow rate shower head can conserve water by using a shallow bath instead. In most cases, but not all, showering is more water efficient than using a bathtub under typical circumstances.
While bathtub water usage is indifferent to duration of the event, water usage from showers is greatly influenced by durations. It is important to eliminate other activities when showering. For example, shaving while in the shower can double or triple the amount of water used. These activities are better managed while taking a bath, rather than a shower because the bath water usage remains constant. Similarly, showering with a friend (as some suggest) is not likely to save water if the duration of the showering event exceeds 15 minutes.
"Navy Showers" and Lathering Valves
An additional method to reduce water use in showers is to turn off the water while lathering and shampooing, often called a “navy shower”. The method requires three steps: 1) turn on water to rinse body and hair; 2) turn off water while shampooing hair and washing body with soap and washcloth; 3) resume water flow and rinse off all shampoo and soap.
Using this technique, the total duration water flow can easily be reduced to 5 minutes or less. This is more easily performed when an on-off or lathering valve is attached to the showerhead so the water temperature remains properly adjusted at the desired level. Many water efficient showerheads have integral shut-off valves already attached. Separate “shut-off” or “lathering” valves can be purchased at many hardware stores, and are easily installed between the shower neck and the showerhead. Many organizations (including manufacturers) promote the installation of these showerheads.
However while such a valve appears to enable the user to save water, not all homes can use the device. In rare cases, it also might endanger that user and lead to thermal shock and/or scalding when the water flow is resumed. In households where the water pressure on the cold water side differs from that on the hot water side (most often where a hot water re-circulating pump exists), closing this small valve could result in hot water flowing into the cold water leg or vice-versa. Depending upon the length of time the valve is closed and the variance in line pressures, when the valve is opened, the temperature of the water exiting the showerhead can be significantly different than it was prior to closure. This sudden temperature shift results in a shock to the body (potentially causing a slip and fall) and possibly scalding in those instances where hot water has backed into the cold water line. For these reasons, showerheads with integral shut-off valves or separate valves designed to be installed between the shower arm and the showerhead are not recommended in the following cases: (1) pre-1987 homes where no scald protection valve is installed behind the wall; (2) showers with flow rates below 2.0 gallons per minute (7.6 Lpm); and (3) showers that are used by elderly or infirm people more easily subject to thermal shock, slipping and falling.
Shower Spray Types
Most showerheads are designed to produce a water spray in one of three major categories: a) stream spray; b) atomizing spray; or, c) aerating spray. There is no one best type, for individual preferences determine user satisfaction among the different models. Each type has advantages and disadvantages.
Stream spray showerheads emit the water in many (often more than 20) small continuous streams, and the streams are set in a circular pattern to balance coverage area and comfort. Most users find the water temperature remains fairly constant, but the velocity of the water emitted is somewhat hampered by the need to retain water flow below 2.5 GPM (9.5 Lpm).
Atomizing showerheads use the turbulence of the water passing through the head to create water droplets, and emitting these droplets at high velocity. Most users find the high velocity of the water to be pleasantly invigorating and assisting the rinsing of shampoo from thick hair. The spray pattern is circular, and more filled-in compared to stream spray heads. The disadvantage is the small water droplets tend to cool down quickly as they pass through the air. Some users complain of the water spray feeling hot on their shoulders while cold on their lower legs. This cooling effect also caused an updraft of air in the shower stall, which causes billowing of shower curtains during the shower. Atomizing spray heads were very popular with utility conservation programs in the 1980s and 90s, partially due to the low cost of manufacturing. Advancements in alternate designs and concerns for customer satisfaction has made these models less popular.
Aerating showerheads are very similar to atomizing models, with the addition of air mixed in with the water inside the head through venturi action. The aeration assists in the water appearing more voluminous to the shower user. Unfortunately, the aeration increases the heat transfer of the water, cooling the water faster than even the atomizing spray.
Newer showerhead designs employ multiple sprays types to take advantage of the beneficial aspects of each type of head. These “hybrid” showerheads have resulted in greater consumer satisfaction and water savings. A utility planning to implement a showerhead replacement program should choose products very carefully. Dissatisfied users will remove the showerhead, or tamper with the flow controls; resulting in no water savings. Only the showerheads that remain installed and used will save water for the utility and customer.
Re-circulating Showers
With rare exception, re-circulating showers are not designed or operate in a water efficient manner. These systems are often called “vertical body spas” and they often use more water than a typical shower or bath. The re-circulation pumps require a reservoir of water in the shower basin to properly operate. Some makes and models of these systems require more than 45 gallons (170.3 L) of water in the basin – more than twice the water usage of a typical shower. The user cannot use any soap or shampoo during the system operation; the spray heads would start emitting suds at a very high velocity. The user must take a “real” shower after the re-circulating shower, adding additional water usage to the event.
Multiple Showerheads
There is a rapidly growing trend to install multiple showerheads in single user shower stalls, in attempts to subvert the Federal requirements of 2.5 GPM (9.5 LPM) maximum flow rate for showerheads. There are current efforts to develop plumbing code regulations to close up this loophole. Water conservation advocates are encouraged to support local, state and nation
al
ef
forts to restrict showerhead installations to standardized health codes of no more than one showerhead per 1296 square inches (8281 square centimeters) of shower stall floor area, and require showerheads to be at least 36 inches apart (.91 m). This proposed requirement would not allow a second showerhead installed unless the shower stall was designed for two persons (minimum of 2592 square inches of floor area).
For more information on showers and non-compliant showerheads and showering systems access these Alliance for Water Effiency web resources:
The question is often asked: What uses more water, a shower or a bath? The answer has been and always will be, “It all depends …… ”.
Showers are typically the third largest water use in the residential setting after toilets and clothes washers. According to the AWWA Residential End Uses of Water study, the average American shower uses 17.2 gallons (65.1 L) (and lasts for 8.2 minutes at at average flow rate of 2.1 gpm (7.92 Lpm) ((Mayer, et. al, 1999).
Water Usage and Bathing Method
Showers
Two factors influence the water usage of a shower: flow rate and duration. Current national energy policy act (EPAct) standards mandate that all showerheads manufactured in the U.S. have a maximum flow rate of 2.5 gpm (9.5 Lpm). There are certainly some showerheads and shower systems that exceed this flow rate, and others that use 1.5 gpm or less (5.7 Lpm).
Before 1980, many showerheads exceeded 5 GPM (18.9 LPM). Energy conservation initiatives enacted regulations to limit shower flows to reduce hot water usage and consequently the natural gas and electricty used to heat water. In the mid-1980s, some states restricted flows to 3.5 GPM (13.2 LPM), and later reduced further to 3.0 GPM (11.4 LPM). The Federal Energy Policy Act set a nationwide regulation to limit showerheads to a maximum flow of 2.5 GPM (9.5 LPM) in the mid-1990s, following California’s mandate in 1992.
The duration of the shower has equal effect on water usage. A 20 minute shower will use twice as much water as a 10 minute shower taken at the same flow rate. Many have hypothesized reducing flow rates of shower heads might cause users to take much longer showers. Scientific studies that monitored thousands of homes across the nation have proven the flow rates have little influence on the duration of the shower. In fact, users of 2.5 GPM (9.5 LPM) shower heads increase the duration of the shower less than 1 minute, compared to those showering with 3.5 GPM (13.2 LPM) shower heads.
Learn more about showerhead flow restrictors and timer devices here:
Shower Flow Restrictors Introduction
Shower Timers Introduction
Baths
The size of the bathtub, and the level the user fills the tub also affects water use. With the exception of whirlpool and jetted tubs, the size of standard bathtubs in North America has generally decreased over time. The typical modern (non-jetted) bathtub today will hold approximately 25 to 45 gallons (94.6 L to 170.3 L) of water depending upon the fill level. A person who only fills the tub half-way will consume approximately 20 gallons (75.7 L). Bathers that fill the tub up to (or exceeding) the owerflow valve will use 40 to 50 gallons (151.4 L to 189.2 L).
Showers vs. Baths
The response to the opening question can best be illustrated in the following chart.
* Shower spa consumption includes the water usage of the soap/shampoo shower required after the spa event
As the chart illustrates, a person that takes long showers or uses a high flow rate shower head can conserve water by using a shallow bath instead. In most cases, but not all, showering is more water efficient than using a bathtub under typical circumstances.
While bathtub water usage is indifferent to duration of the event, water usage from showers is greatly influenced by durations. It is important to eliminate other activities when showering. For example, shaving while in the shower can double or triple the amount of water used. These activities are better managed while taking a bath, rather than a shower because the bath water usage remains constant. Similarly, showering with a friend (as some suggest) is not likely to save water if the duration of the showering event exceeds 15 minutes.
"Navy Showers" and Lathering Valves
An additional method to reduce water use in showers is to turn off the water while lathering and shampooing, often called a “navy shower”. The method requires three steps: 1) turn on water to rinse body and hair; 2) turn off water while shampooing hair and washing body with soap and washcloth; 3) resume water flow and rinse off all shampoo and soap.
Using this technique, the total duration water flow can easily be reduced to 5 minutes or less. This is more easily performed when an on-off or lathering valve is attached to the showerhead so the water temperature remains properly adjusted at the desired level. Many water efficient showerheads have integral shut-off valves already attached. Separate “shut-off” or “lathering” valves can be purchased at many hardware stores, and are easily installed between the shower neck and the showerhead. Many organizations (including manufacturers) promote the installation of these showerheads.
However while such a valve appears to enable the user to save water, not all homes can use the device. In rare cases, it also might endanger that user and lead to thermal shock and/or scalding when the water flow is resumed. In households where the water pressure on the cold water side differs from that on the hot water side (most often where a hot water re-circulating pump exists), closing this small valve could result in hot water flowing into the cold water leg or vice-versa. Depending upon the length of time the valve is closed and the variance in line pressures, when the valve is opened, the temperature of the water exiting the showerhead can be significantly different than it was prior to closure. This sudden temperature shift results in a shock to the body (potentially causing a slip and fall) and possibly scalding in those instances where hot water has backed into the cold water line. For these reasons, showerheads with integral shut-off valves or separate valves designed to be installed between the shower arm and the showerhead are not recommended in the following cases: (1) pre-1987 homes where no scald protection valve is installed behind the wall; (2) showers with flow rates below 2.0 gallons per minute (7.6 Lpm); and (3) showers that are used by elderly or infirm people more easily subject to thermal shock, slipping and falling.
Shower Spray Types
Most showerheads are designed to produce a water spray in one of three major categories: a) stream spray; b) atomizing spray; or, c) aerating spray. There is no one best type, for individual preferences determine user satisfaction among the different models. Each type has advantages and disadvantages.
Stream spray showerheads emit the water in many (often more than 20) small continuous streams, and the streams are set in a circular pattern to balance coverage area and comfort. Most users find the water temperature remains fairly constant, but the velocity of the water emitted is somewhat hampered by the need to retain water flow below 2.5 GPM (9.5 Lpm).
Atomizing showerheads use the turbulence of the water passing through the head to create water droplets, and emitting these droplets at high velocity. Most users find the high velocity of the water to be pleasantly invigorating and assisting the rinsing of shampoo from thick hair. The spray pattern is circular, and more filled-in compared to stream spray heads. The disadvantage is the small water droplets tend to cool down quickly as they pass through the air. Some users complain of the water spray feeling hot on their shoulders while cold on their lower legs. This cooling effect also caused an updraft of air in the shower stall, which causes billowing of shower curtains during the shower. Atomizing spray heads were very popular with utility conservation programs in the 1980s and 90s, partially due to the low cost of manufacturing. Advancements in alternate designs and concerns for customer satisfaction has made these models less popular.
Aerating showerheads are very similar to atomizing models, with the addition of air mixed in with the water inside the head through venturi action. The aeration assists in the water appearing more voluminous to the shower user. Unfortunately, the aeration increases the heat transfer of the water, cooling the water faster than even the atomizing spray.
Newer showerhead designs employ multiple sprays types to take advantage of the beneficial aspects of each type of head. These “hybrid” showerheads have resulted in greater consumer satisfaction and water savings. A utility planning to implement a showerhead replacement program should choose products very carefully. Dissatisfied users will remove the showerhead, or tamper with the flow controls; resulting in no water savings. Only the showerheads that remain installed and used will save water for the utility and customer.
Re-circulating Showers
With rare exception, re-circulating showers are not designed or operate in a water efficient manner. These systems are often called “vertical body spas” and they often use more water than a typical shower or bath. The re-circulation pumps require a reservoir of water in the shower basin to properly operate. Some makes and models of these systems require more than 45 gallons (170.3 L) of water in the basin – more than twice the water usage of a typical shower. The user cannot use any soap or shampoo during the system operation; the spray heads would start emitting suds at a very high velocity. The user must take a “real” shower after the re-circulating shower, adding additional water usage to the event.
Multiple Showerheads
There is a rapidly growing trend to install multiple showerheads in single user shower stalls, in attempts to subvert the Federal requirements of 2.5 GPM (9.5 LPM) maximum flow rate for showerheads. There are current efforts to develop plumbing code regulations to close up this loophole. Water conservation advocates are encouraged to support local, state and nation
For more information on showers and non-compliant showerheads and showering systems access these Alliance for Water Effiency web resources:
