Selecting Better Toilets by Design

Water efficiency and durability combine to produce superior results

Peter J. Arsenault, FAIA, NCARB, LEED-AP

Architects and other design professionals recognize that water usage is a growing critical concern in buildings of all types. Green building standards address overall water conservation, government regulations and codes dictate performance for specific plumbing fixtures, and end users seek responsible, affordable solutions. Historically, one of the biggest users of water has been the common flush toilet. Since all buildings have multiple restrooms or bathrooms with one or more toilets, making selections based on their water efficiency will directly impact overall water usage. However, like all fixtures in a building, the toilets must also meet all other design requirements for a particular building including long-term, reliable operation and integration with space design. Therefore, since there are many different choices available on the market, it is important to have a fundamental understanding of what to look for when selecting and specifying the most appropriate toilet fixture for a particular project.

Consider the Flush Toilet

We can easily take it for granted, but if we think about it, the flush toilet is one of the most enduring and relied upon things that we include in buildings. It uses no electricity to operate, has relatively few moving parts, and uses some rather sophisticated product design to function repeatedly for years without leaks. All we need to do is travel to someplace where they aren’t available and we realize the contribution they make to sanitary and hygienic living when connected to appropriate infrastructure.

Where did this important invention come from? Like all good products, it evolved over time. As early as Greco-Roman times, water was used for carrying away waste. Communal latrine style facilities built of masonry and stone are found in ruins around the Mediterranean that were constructed directly over flowing streams or creeks. While this approach lacked any treatment process to stop environmental contamination, it did keep the community itself more sanitary. This approach of keeping such facilities separate from buildings for living and working dominated for a considerable time period until eventually other options started to develop and emerge. While aristocrats and nobility seemed to have the luxury sooner, it wasn’t until the 1700s and 1800s however that innovations came about allowing average people to seriously consider bringing the toilet indoors. In both England and the U.S., early versions of the flush toilet used wooden water tanks raised up from a lower bowl that simply relied upon releasing a significant amount of water to flow from the tank through the bowl in order to operate. When it was placed in its own room without any other fixtures, it gained the name of the “water closet.”

The early 1900s saw the design of flush toilets begin to take the form we are familiar with today. Several inventors and manufacturers focused on the use of porcelain as the dominant material for both the bowl and the now closely aligned water tank. They developed variations in the way that they worked, the internal mechanisms that allowed water to flow and stop (i.e. flush), and integrated the curving plumbing trap into the bottom outlet to allow water to remain in the bowl afterwards. For decades, their acceptance, use, and sheer numbers grew to the point where they became commodities that were first expected and then required by code in every habitable building in the U.S. With a common perception that water was abundant and available and all buildings could be connected to underground infrastructure for treatment, there was little need to worry too much about efficiency, just functionality.

Regulations and Standards

Things began to change in the 1970s following the oil embargo when the first Energy Policy and Conservation Act was passed by Congress and signed into law in 1975. This legislation acknowledged that not only was energy a valuable resource that needed to be addressed, but so was water. There are two reasons for this. First, most potable water requires a significant amount of energy to pump, move, treat, process, and deliver to consumers. Only a small fraction of this water is actually consumed by people through drinking or cooking. For example, most residential water is used for washing, showering, and flushing which all typically then require more energy for removing, processing, and treating it before returning the water back to the environment. According to government studies, the average American family of four uses 400 gallons of water per day with approximately 70 percent of that water being used indoors. Bathrooms are identified as being the largest consumer with a toilet alone found to use 27 percent of the water! Hence, reducing the amount of water required by a household, and toilets in particular, directly reduces the amount of energy used to first deliver and then to recover that water. Second, as populations have increased in certain areas of the U.S., the demand for water has also increased to the point where it is exceeding the available reliable supply. In some cases, those supplies are already being disputed for territorial control. The combination of increasing water scarcity and the energy requirements of processing water in aging infrastructure systems have driven the logical inclusion of water conservation in energy legislation ever since.

In 1992, the United States Congress passed the Energy Policy Act, which mandated that beginning in 1994 common flush toilets were only to use only 1.6 US gallons (6.1 L) of water per flush instead of the more common 3.5 gallons at the time. These were sometimes referred to as Ultra Low Flow (ULF) toilets. Some of the initial products offered by some manufacturers became problematic since their design reduced water flow but did not function as well. Those who looked at their products in total were able to design in effective operation as well as reductions in water use to meet the new regulations.

High-Efficiency Toilets (HETs)

Manufacturers have continued to improve their products to use less water without sacrificing functional performance. Those toilets that have achieved full operation while using only 1.28 gallons per flush (4.8 liters) or less, are generally identified as high-efficiency toilets or HETs. With a nearly 20% reduction in flush volume compared to ULF toilets, HETs have become the new sustainability standard for toilets. Some operate with a consistent single-flush operation using the full flush volume each time. Others have a dual-flush operation allowing for a choice in how much water is used based on a full flush for solid matter and a lower setting for liquids only. While most HETs function traditionally purely on water, others achieve even higher efficiencies and performance by using compressed air to create a pressure-assisted flush. These products can operate with as little as 1.1 gallons per flush and represent a 30% water savings compared to ULF toilets; up to 60% or more compared to older toilets that may still exist in some buildings.

When considering operational performance, the Maximum Performance (MaP) score is the common standard used. It is measured by a score in the range of 250 to 1,000 which is intended to represent simulated grams of solid matter. A toilet with a MaP score of 1,000 should remove all waste with a single flush, not plug, not harbor any odor, and be easy to keep clean. The minimum performance threshold for a toilet to be considered an HET is a MaP score of 350. As a practical matter, most manufacturers shoot for the maximum score of 1,000 to demonstrate full functionality. It should be kept in mind, however, that while this is an important test and indicates a good measure of performance, it is done as a test one time on a new toilet. As such, a MaP score is not an indicator of reliability over time to continue to achieve that score. Rather, the design and make-up of the components of the product are better indicators of durability and reliability.

Handicapped Accessibility

Another significant factor that has influenced toilet designs in recent decades is the enactment of the Americans with Disabilities Act (ADA) and the broad adoption of ICC / ANSI 117.1 standards that address handicapped accessibility in buildings. Since most building codes have incorporated or attached by reference these standards for public buildings, and public rest rooms and bathrooms in particular, toilets must comply in several ways. Architects are familiar with, and generally focus on, things like access, clearance, and distance to walls that are required to be compliant. Toilet manufacturers focus on other things to be sure that their product can comply with the standards and be labeled as handicapped accessible. The first is the height of the seat measured from the floor. While a traditional toilet will measure on the order of 16 inches or less, the ICC / ANSI requirements are for a somewhat taller 17 – 19 inches from floor to top of seat. This added height is closer to a wheelchair seat height making transfer easier when needed or eases general standing and sitting for ambulatory handicaps. The other major requirement is for the operation of the toilet which needs to match the general mandates for any operable parts in buildings to be considered accessible. Specifically, they must be operable with one hand and shall not require tight grasping, pinching, or twisting of the wrist. Further, the force required to activate operable parts shall be 5.0 pounds (22.2 N) maximum. Most flush operations can achieve this but they must be tested and proven in order to be classified as handicapped accessible.

The benefits to handicapped persons in having toilets meet these standards are fairly obvious, but it is interesting to note that able bodied consumers are weighing in too. Manufacturers have noticed a trend for consumers to request these handicapped accessible toilets in homes or other facilities simply because they prefer them. This may be borne from people using them in public facilities or having them recommended for older people in general, but either way, this is one area where the concept of “universal design” seems to be taking hold. By this way of thinking, facilities and environments are designed with everyone in mind (hence the “universal”) not just those with special needs due to physical handicaps. Designing for current trends and preferences for all, seems to make more sense than sticking with tradition for its own sake.

Flush Toilet Types and Applications

Modern day toilets have clearly evolved to meet a variety of performance and regulatory demands. Within that framework, though, there are variations and options that accommodated different types of building applications, different budgets, different design styles, and different degrees of durability based on anticipated use. Some of those variations are discussed as follows.

Bowl Types and Applications

The common material of choice for bowls is vitreous china which is long lasting, and able to be glazed with a very smooth and sanitary surface that is impervious to water. It is also readily formed into sizes and shapes to suit different needs. The common round shaped bowl is common and space efficient making it particularly good for tight spaces. An elongated shape is often preferred when space allows both for appearance and comfort. A new option is available from some manufacturers that is referred to as a compact elongated bowl meaning that it retains the elongated shape but uses less space to do so. This makes it particularly good for retrofit applications or for handicapped accessible areas where additional space is needed. In any case, the bowl can be stylized to create a particular look appropriate for traditional, transitional, or contemporary design styles.

The internal shape and configuration of the bowl is a significant part of the successful operation of the toilet overall. The water comes down in to the bowl through openings in in the perimeter rim, which are designed to act as multiple rim jet inlets of various capacities. As the water rises in the bowl, it causes the serpentine shape of the outlet to fill and create a siphoning action that moves everything into the drain pipe. All of this internal shaping and working also directly affect the amount of water needed for the proper flushing of the toilet. Hence, this is one area where different manufacturers spend a good bit of design time and effort to refine, improve, and optimize performance for water efficiency.

The base of the bowl also has some variations. Better models have a broader footprint, making them more stable and spreading weight out a bit more. They are also particularly good for retrofit since they can cover over a broader floor area that may have been affected by a previous toilet. Another option is to select a toilet with no floor base but rather use a rear outlet wall mounted toilet. This can help with floor clearances particularly in handicapped accessible situations.

Tank Sizes

The tank is simply the portion of the toilet that receives and stores water for the next flush. Although the capacity of the tank in terms of gallons of water held for each flush can be held constant for a given design, the physical size and shape can vary. Some of the variation will depend on style. For example, a one-piece toilet with a more contemporary design will commonly include a tank portion that is lower in height and generally appears understated. More typically, the tank is a separate component, also made of vitreous china that connects directly to the inlet in the bowl component. It can be shaped to favor a more round or more square appearance based on its overall design style to match the bowl style.

A significant distinction among tank sizes is the depth from front to back. In most situations it is preferred that the back of the tank sits fairly tight to the wall behind it. However, its location on the bowl is fixed and the location of the bowl is determined by the plumbing rough-in for the sanitary drain line. Usually that rough-in is located such that the center of the sanitary drain line is 12 inches from the wall. Most tanks are designed with a 12 inch rough-in in mind. However, we all know that field conditions do vary and sometimes that rough-in location calls for a shallower or a deeper tank to avoid either a conflict with the wall or a gap behind the tank that is too large. For these situations, manufacturers offer alternative tank depths to accommodate drain line rough-ins ranging from 10 inches to 14 inches that otherwise function the same and essentially have the same appearance as the standard 12-inch rough-in tanks. Hence a plumbing contractor can choose a tank with an appropriate depth and match it with the specified bowl type (round, elongated, ADA compliant, etc.) to achieve a proper installation.

Flush Valve Types

The flush valve is the operational mechanism within the tank that constitutes the “moving parts” of the toilet. All of them rely on a lever or push button operation activated by one hand of the user. That action releases or moves a flapper type of plug such that the full volume of water is allowed to flow down by gravity quickly into the bowl. The flow of water down around the rim causes the swirling action that raises the water level in the bowl and the outlet causing a siphon action that drains everything away. Once the tank is empty, the flapper plug falls back into place closing the connection between the tank and bowl. Concurrently, a float valve of one type or another is used to turn the flow of fresh water on or off. When the tank is full the float is raised up and closes a small valve that would otherwise let water flow into the tank. When the tank is emptied by the lever / flapper plug action, the float drops allowing the valve to open and new water to run into the tank. A smaller amount of fresh water is also channeled down into the bowl to refill it as well. As the tank and bowl re-fill to the designated level, the float rises up again and closes the valve leaving everything ready for the next operation.

The variation between different versions of flush valves often comes down to materials used and minor variations in design. Levers can be placed on the front or side of the tank depending on style while push buttons are often placed on the top. The flapper plug can be shaped in various forms and made from various types and thicknesses of plastic or rubber depending on the durability needed. It can also be connected to the lever by plastic pieces or more durable metal lever arms and beaded chain. The float valve can be a horizontal style or a space saving vertical style that runs up and down along the flush valve mechanism.

Perhaps the biggest modern advance in flush valves is the use of compressed air to assist in the flushing operation. In this system, a re-designed mechanism traps air in a smaller compartment within the tank. As water fills, it uses the water supply line pressure to compress the trapped air inside. The compressed air is what then forces the tank water into the bowl. Hence, instead of the siphon action of a gravity unit that pulls the water down, the pressure-assist unit pushes water and waste out. This flushing action is obviously more vigorous and manufacturers state that it cleans the bowl better than gravity units. This claim is borne out by the fact that some achieve MaP scores above 1,000 on the order of 1,250 or so certainly by virtue of the addition of the compressed air. The pressure assist is also a particularly good option for larger buildings such as hotels or motels or other situations where the flushing distance is longer to get to the main drain line. Of course, there is a little bit of a price premium and the amount of water needed may vary between models, but they may be the best long-term choice for higher use situations. They are also available with a dual-flush operation meaning that they can be activated to use on the order of 1.1 gallons per flush or 1.6 gallons per flush by varying the amount of air and water that are pushed through.

Green Building Contributions of Flush Toilets

As we have seen, attention to water usage and conservation is a notable concern. While some minimum standards are mandated by regulation, many design professionals are more interested in achieving superior performance as part of an overall green building strategy. In that regard, there are two notable programs that both encourage and recognize water efficiency as part of an environmentally sustainable building.

U.S. EPA WaterSense

Launched in 2006, WaterSense is a voluntary partnership program sponsored by the U.S. Environmental Protection Agency (EPA). It is designed to make it easy for Americans to save water and protect the environment by choosing water-efficient products and services. Items that meet WaterSense specifications must be independently tested and certified, and only then can they carry the WaterSense label. Generally, WaterSense labeled products will be about 20 percent more water efficient than their code minimum counterparts in the same category.

When it comes to toilets, the WaterSense threshold is a maximum 1.28 gallons per flush or less while still providing equal or superior performance. This is 20 percent less water than the current federal standard of 1.6 gallons per flush. In order to earn a WaterSense label, toilets must be independently certified to meet rigorous criteria for both performance and efficiency. Only toilets that complete the third-party certification process can display the WaterSense label.

The significance of this program is notable. By replacing old, inefficient toilets with WaterSense labeled models, an average family can reduce water used for toilets by 20 to 60 percent—that’s nearly 13,000 gallons of water savings for a typical home every year. Nationally, if all old, inefficient toilets in the United States were replaced with WaterSense labeled models, it could save 520 billion gallons of water per year, or the amount of water that flows over Niagara Falls in about 12 days. From an economic standpoint, the average homeowners could save more than $110 per year in water costs, and $2,200 over the lifetime of the toilets. Further, in many areas, utilities offer rebates and vouchers that can lower the price of a WaterSense labeled toilet.

Whether remodeling a bathroom or designing the construction of a new building, it is worth considering installing WaterSense labeled toilets as a high-performance, water-efficient option. These labeled toilets are available at a wide variety of price points and a broad range of styles by numerous manufacturers. Further, many water utility companies are encouraging their use by offering rebates on the order of $50 – 200 per HET toilet with specific details and requirements for these incentives varying by location. For more information or a list of WaterSense labeled products, visit www.epa.gov/watersense. To learn more about finding rebates for a particular location, see http://www.epa.gov/WaterSense/rebate_finder_saving_money_water.html

LEED® by the U.S. Green Building Council

The green building movement in this country has given rise to quantifiable rating systems that seek to establish specific levels of achievement in the creation and performance of green buildings. The best known of these green building rating systems has been developed by the U.S. Green Building Council and known as the LEED® rating system. The LEED 2009 system is in place until the year 2015 which overlaps with LEED version 4 introduced late in 2013. Since buildings are currently being designed under both systems, it should be noted that credits may be earned somewhat differently for each when seeking certification. This family of green building rating systems also includes one specifically for homes updated in 2013 and referred to as LEED for Homes version 4.

LEED is a comprehensive rating system that addresses Water Efficiency as one of its fundamental categories in all building situations. In LEED v. 4, toilets are specifically addressed as part of the overall intent to reduce indoor water consumption. First there is a prerequisite that toilets use 20 percent less water than the code baseline of 1.6 gallons per flush. That prerequisite further states that “All newly installed toilets …that are eligible for labeling must be WaterSense labeled (or a local equivalent for projects outside the U.S.)”. Hence, in order to even consider LEED certification, HET / WaterSense labeled toilets are an automatic, entry level item at 1.28 gallons per flush performance. In order to earn actual points for indoor water conservation, the water consumption must be lower still. Depending on the particular LEED program used (i.e. New Construction, Schools, Core & Shell, etc.) between 1 to 7 points are available for these further reductions. Generally, each 5 percent of further reduction will earn one point such that 25 percent total reduction garners 1 point, 30 percent achieves 2 points and so forth. This can be achieved in part by using toilets that achieve higher efficiencies than WaterSense products (i.e. 1.1 gallon per flush models). Since the focus is on reducing potable water use, it can also be achieved in part by channeling “grey water” from sink and shower drains to be used for flushing toilets.

For LEED for homes, there is a choice within the Water Efficiency category to follow either a Performance Path option by using a computer-modeled level of water performance or a Prescriptive Path option by following a checklist of specific items. In some cases it is worth looking into both options and determining which produces the better results and higher potential rating.

Specifying Flush Toilets

When specifying and selecting the best toilet for a particular building or design application, it should be clear by now that there are choices and details to pay attention to. The Master Format section number commonly used is 22 41 13 for Residential Plumbing Fixtures and 22 42 13 for Commercial Plumbing Fixtures. Some of the relevant items to address in a standard 3-part specification format are highlighted as follows.

Part 1 General

When it comes to specifying the most appropriate toilets for a particular building, especially a green building, the first place to look at is testing certifications and labels. Calling for HET and WaterSense labeled toilets are likely a minimum requirement. It may be appropriate to call for MaP ratings as well, particularly if you are looking for a fixture with a rating of 1,000. If a handicapped accessible designation is also required that should be referenced.

Submittals will be similar to most plumbing products for information and confirmation of specification compliance. There may also be the need for coordination drawings or details with the rest of the plumbing system design. Other general specification items should include warranty requirements. Vitreous china commonly carries a limited lifetime warranty, pressure valves up to a 10-year warranty and 5 years for all else.

Part 2 Products and Options

Identifying the details of specific toilets including materials and options that are desired requires covering several items. If multiple product types are selected for a building, then obviously they each need to be specified and their locations identified on the drawings.

The basic size and configurations of the vitreous china tanks and bowls need to be identified as to round, elongated, or compact elongated. If a particular manufacturer’s style is required, that should also be spelled out. It is also important to identify the color of the vitreous china glaze. White is the common default color with an off-white also offered as standard by most manufacturers. There are other custom colors available as well that will vary by manufacturer.

Next to identify is the flush valve details including the required gallons per flush performance. If a compressed air valve is required that should be clearly called out with all other corresponding performance requirements. From there, the flush valve can be specified with particular materials or by types to suit the durability and usage frequency of the toilets.

Part 3 Installation

Installing toilets is generally straightforward but usually requires the skill of a plumbing subcontractor for best results. In the event field conditions dictate it, the plumbing subcontractor should have the flexibility and freedom to change the tank to suit the depth needed for a proper installation. In all cases, manufacturer’s recommendations should be followed for installation, cleaning, and testing.

Conclusion

Architects concerned with green building design or meeting clients’ performance expectations in general understand the need to address water use reduction in buildings. Recognizing that one of the biggest users of water in a building can be the common flush toilet is the first step toward controlling that water usage. Using the information from this discussion can allow architects and other design professionals to discern the different performance and water reduction capabilities of the different types of toilets available. With that information, the best and most appropriate choices and selections can be made to specify products that suit both the overall design and functional performance goals of a building.

Peter J. Arsenault, FAIA, NCARB, LEED AP, is a nationally known architect, sustainability consultant, technical writer, and continuing education presenter. www.linkedin.com/in/pjaarch

 

Founded in 1932, Gerber Plumbing Fixtures LLC is a leading manufacturer of high performance plumbing fixtures, faucets and fittings sold exclusively through professional wholesalers throughout the United States and Canada. Gerber has a comprehensive residential and commercial product offering, including HET toilets, HEU urinals and WaterSense certified faucets. www.gerberonline.com