EXECUTIVE SUMMARY

Toilets in the U.S. have been designed to use less water to help meet water supply planning needs. However, the basic technology employed – that of a siphonic flush – has not changed. When the National Energy Policy Act reauthorized the U. S. Department of Energy in 1992, national standards for water use were included. The included toilet standard matched the industry standard for low-consumption toilets, mandating a 1.6 gallon per flush (gpf) toilet instead of the previous industry standard “Water Saver” toilet which used 3.5 gpf. Most toilet manufacturers adapted by keeping the 3.5 gallon toilet tank to provide the head for a forceful flush, while adjusting the inner workings of the toilet to achieve the 1.6 gallon flush. The two most common adaptations were to install a flush-valve flapper which closes before all the water escapes the tank (early-close flapper) or to install a plastic bucket, or toilet dam, which retains some water in the toilet tank behind the dam, thus lowering the volume of flush. Some manufacturers switched to low-capacity tanks with a standard flapper, and others chose to utilize a new pressurized flush technology.

Since 1.6 gpf, low-consumption toilets became the standard, there have been anecdotal reports of problems with their functioning, including a need for multiple flushes to clear the bowl, and frequent clogging. More anecdotal evidence suggests that the functioning of some early low- consumption toilets has continued to decline as they age. Even though low-consumption toilet performance has improved since the first models, many current models still rely on the same adjustments to the 3.5 gallon toilet. Lack of correct replacement parts seems a likely contributor to a possible decline in toilet performance with age, as early-close flappers are replaced with generic flappers which allow a 3.5 gallon flush, or as toilet dams are removed. Research on the functioning of aging low-consumption toilets can serve as a starting point for discussion of the extent of the problem, especially the decline in performance due to aging and replacement of parts.

Households that participated in the City of Tucson Water Department’s low-consumption toilet rebate program in 1991-1992 were selected for study in order to investigate the functioning of older low-consumption toilets. Data loggers were attached to the water meter on the water line going to each house, and four days of data at a 10-second interval were recorded. Data gathered from 170 homes were analyzed using specialized software for identifying toilet flushes. Toilet flushes were measured according to their peak flow, duration and volume of flush and compared to the expected inventory of toilets in the home. A follow-up survey confirmed the number and type of toilets in the household, asked about toilet function problems, and elicited a rating of owner satisfaction with the functioning of these low-consumption toilets.

Results

Data logging revealed that more than half (57.1%) of homes with approximately 7-year-old toilets supplied through Tucson Water’s low-consumption toilet rebate program had no detectable problem with their function. While this result is encouraging, considering the alterability of many brands of low-consumption toilet, several types of problems were detected, including high flush volumes, an increase in double flushing compared to 3.5 and 5 gallon toilets, and recurring flapper leaks.

Data-logging revealed the average flush volume for all rebate toilets was 1.98 gallons per flush, or about 24 percent higher than the 1.6 gallons per flush they were designed to use. As is shown

in Table ES-1, 26.5 percent of households had at least one low-consumption rebate toilet with a high flush volume, averaging greater than 2.2 gpf.

Double flushing was considered a problem if it occurred once a day or more. Double flushing occurred in 14.2 percent of homes with rebated toilets, or 10.9 percent of rebated toilets. Data logging revealed that occurrence of frequent double-flushing was higher for rebated low- consumption toilets than for non-low-consumption, non-rebate toilets. The difference in proportions between the 10.9 percent of rebated low-consumption toilets requiring frequent double flushing and 6.6 percent of non-rebate, non-low-consumption toilets requiring double flushing is statistically significant, but not large. The small difference in double flushing problems between low-consumption and non-low-consumption toilets underscores the fact that double flushing is not confined to low-consumption toilets, but some models of low- consumption toilet do require more double flushing than non-low-consumption toilets.

A third problem identified was recurring flapper leaks. At least 12.1 percent of households had recurring flapper leaks in their low-consumption rebate toilets. It appears that flapper leaks

Table ES-1. Low-Consumption Toilet Problems by Flush Valve Type

1. Number of homes from which a toilet with this type of flush mechanism was removed.

2. Calculation of Some Problem’ includes homes from which toilets were removed due to poor function. Pressurized toilets were removed from three homes due to poor function. A toilet with an early-close flapper was removed from one home because the toilet was rendered inoperable by actions of children in the household, not poor function.

occurred at a higher rate in low-consumption rebate toilets than in non-low-consumption non- rebate toilets, but it was not possible to determine the exact amount of difference in the rate of flapper leaks because of difficulties in determining the source of some flapper leaks.

As a result of these toilet function problems, it appears that water savings projections used in planning by a utility over the expected 20-year life of these 1991-92 year low-consumption toilets would need to be adjusted downwards to accurately accommodate the increase in average flush volume due to deterioration in toilet function over time and persistent toilet leaks. This adjustment should incorporate the 24 percent higher average flush volume measured for low- consumption toilets, as well as the higher rate of recurring flapper leaks and slightly higher rate of frequent double flushing in the rebated low-consumption toilets compared to non-low- consumption toilets.

Despite the ease with which early-close flappers can be replaced with standard flappers, it does not appear that early-close flappers are more likely than other flush valve mechanisms to produce high flush volumes or any other low-consumption toilet problem. Double flushing, high volume flush and flapper leaks in toilets with early-close flappers occurred at a slightly lower rate than for all types of toilet.

Low-consumption toilets with a standard flapper performed about average, with 39.1 percent of homes with some problem compared to 42.9 percent for all types. This type of toilet had the highest rate of frequent double flushing among flush mechanism types, with 21.7 percent of homes. Toilets with a standard flapper had a slightly below average rate of high flush volume (26.1%) and a below average rate of flapper leaks (8.7%).

Toilets with a toilet dam and a standard flapper performed worse, on average, than toilets with an early-close flapper or a standard flapper. Toilets with a toilet dam showed some problems with toilet function in 51.2 percent of homes. Toilets with toilet dams had the second highest rate of double flushing (17.1%) and the highest rate flapper leaks (17.1%) compared to other flush mechanism types. Easy alterability of toilet dams may help to explain worse performance of this type of mechanism.

Toilets with a specialized tube and bell flush mechanism performed the worst. Some toilet function problem was detected in 55.6 percent of homes with toilets with a tube and bell flush mechanism. Toilets with this mechanism had by far the greatest percentage of homes with high flush volume (44.4%). It is possible that some homeowners have installed the 3.5 gallon design of this mechanism in their toilets as a replacement, or have modified the 1.6 gallon mechanism to flush at a greater volume.

Pressurized toilets performed best compared to toilets with other flush mechanisms. Pressurized toilets had the lowest percentage of homes with frequent double-flushing, the lowest percentage of homes with high flush volumes and the lowest percentage homes with some low-consumption toilet problem. The percentage of homes with pressurized toilets with some toilet function problem would have been lower had not some been removed for performance problems. High performance ratings for pressurized toilets revealed that owners were either very happy with their pressurized toilets or dissatisfied enough to remove them.

The survey of homeowners showed that 85 percent of those replacing their flappers had done so by going to the hardware store, where proprietary replacement flappers are usually not available. Also, 24 percent of those who knew they had flappers as toilet flush valves used in-tank bowl cleaners, which may play a role in deterioration of rubber or plastic toilet parts. However, no attempt was made in the survey to distinguish between halogenating cleaners, some of which can cause damage, and non-halogenating cleaners, which do not cause damage.

Recommendations

1. The water industry should collectively press through the ASME/ANSI standards process for toilet designs which are not alterable. This means casting toilet dams as part of the tank if a toilet dam is used. This also mean using tanks with low-consumption capacity that do not require an early-close flapper. Toilets with specialized flush mechanisms should be made so a 3.5 gallon per flush replacement mechanism will not fit into a toilet that was designed to flush 1.6 gallons.

2. The water industry should not offer rebates or direct install programs which include toilets with alterable designs or with specialized parts for which replacements may not be readily available later in the life of the toilet.

3. We endorse Metropolitan Water District of Southern California’s recommendations that a warning be included with new toilet packaging about use of halogenating bowl cleaners and that a program be established to inform all homeowners about the possible effect of halogenating bowl cleaners.

4. Attempts should be made to replicate this study and confirm its findings with other populations of aging low-consumption toilets. One example of a much larger population of similar-age and model low-consumption toilets are those installed under Los Angeles Department of Water and Power’s toilet rebate program.