SUMMARY AND CONCLUSIONS

Data logging of homes with approximately 7-year-old toilets supplied through Tucson Water’s low-consumption toilet rebate program, combined with surveys of more than half the households, revealed that nearly half of aging low-consumption toilets had problems with high flush volumes, frequent double flushing, and/or flapper leaks.

Data logging revealed that the average flush volume for all low-consumption rebate toilets was 1.98 gallons per flush, or about 24 percent higher than 1.6 gallons per flush they were designed to use. In addition, 26.5 percent of households had at least one low-consumption rebate toilet with an average flush volume greater than 2.2 gpf.

Frequent double flushing, which was defined as occurring in at least 15 percent of possible flushing events during a trace (on average about once a day), occurred in 14.2 percent of homes with rebated low-consumption toilets, or 10.9 percent of rebated toilets. Data logging also 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 was statistically significant, but not large. The small difference in double flushing problems between low- consumption and non-low-consumption toilets underlines the fact that double flushing is a problem that is not confined to low-consumption toilets, but that some models of low- consumption toilet do require more double flushing than non-low-consumption toilets.

The survey respondents also reported problems with frequent double flushing. Thirty-eight percent of all rebate low-consumption toilets versus 16 percent of non-rebate, non-low- consumption toilets were reported to require frequent double flushing. This difference was also statistically significant. The rate of frequent clogging was also significantly higher in rebated low-consumption toilets (28% of toilets) than in non-rebate, non-low-consumption toilets (8% of toilets).

In the survey, homeowners were allowed to use their own standard to determine what was frequent double flushing. For interpreting the results from the data loggers, double flushing once per day or more was used to define frequent double flushing. The survey suggested a greater problem with double flushing than did the data loggers. This result indicates that many homeowners considered double flushing to be a problem even if it occurs less than once per day.

Also, at least 12.1 percent of households had recurring flapper leaks in their low-consumption rebate toilets. Flapper leaks were also identified in non-low-consumption toilets. It appears that flapper leaks occurred at a higher rate in low-consumption toilets compared to non-low- consumption toilets, but it was not possible to determine the exact amount of increase in the rate of flapper leaks in rebated low-consumption toilets than in non-low-consumption toilets because of difficulties in determining the source of some flapper leaks.

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 the deterioration in their function over time. This adjustment should incorporate the 24 percent higher average flush volumes measured for low-consumption toilets, as well as the higher rate of recurring flapper leaks and slightly higher rate of frequent double flushing in these low-consumption toilets compared to non-low-consumption toilets. However, the combined effect of flapper leaks and frequent double flushing is smaller than the increase in average flush volume.

Overall ratings of the performance of low-consumption toilets purchased under the rebate program showed that their owners currently view their functioning positively. The average rating of low-consumption rebate toilets of 3.83 was above “neutral” (3) and just shy of “satisfied” (4). The rating for low-consumption rebate toilets was only slightly lower than the average rating given for all non-rebate toilets (3.92) and non-rebate, non-low-consumption toilets (3.93) and is similar to the overall rating of many of the same toilets when they were new as reported in the Los Angeles Department of Water and Power survey of rebate program participants in 1992 (overall rating 7.4 out of 10, or 3.7 out of 5).

Despite the ease with which early-close flappers can be replaced with standard flappers, it does not appear that early-close flappers were 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 or models of toilet. The most common toilet in the study was the Wellworth Lite, which is the only toilet model in 10 or more households which uses an early- close flapper. The Wellworth Lite had the smallest percentage of households with toilets with a problem detectable through data logging (38.2%), as well as below average percentages of homes with frequent double flushing (12.5%), high flush volumes (23.2%) and flapper leaks (10.7%). The Wellworth Lite received an average satisfaction rating of 3.82, which was not statistically different from the mean rating for all rebate toilets.

Low-consumption toilets which use a standard flapper for the flush valve have been designed to a achieve a 1.6 gallon flush without using a toilet dam or an early-close flapper. Some problem with toilet function was found in 39.1 percent of homes with these toilets, which was slightly worse than toilets with an early-close flapper, but below the average for all toilet types or models (42.9%). Toilets with a standard flapper had the highest rate of double flushing of any flush mechanism type, at 21.7 percent. These toilets had the lowest rate of flapper leaks (8.7%) and a slightly below average percentage of homes with high flush volumes (26.1%).

The Atlas is the most numerous of toilets with a standard flapper. This model had above average rates of double flushing (20.0%) and high flush volume (30.0%), and a below average rate of flapper leak (10.0%). The customer satisfaction rating for the functioning of the Atlas was slightly above the mean rating for all low-consumption toilets (3.87, 15 toilets).

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 problem with toilet function in 51.2 percent of homes, compared to 40 percent of homes with a toilet with an early-close flapper. Compared to other flush mechanism types, toilets with toilet dams had the second highest rate of double flushing (17.1%), the highest rate of flapper leaks (17.1%), and an average rate of homes with high flush volumes (26.8%).

However, there were large variations in the functioning of individual models of toilet with a toilet dam. The Lamosa Sahara had the highest percentage of homes with high flush volumes (60%), but had no homes with frequent double flushing. On the other hand, the Preserver had the highest percentage of homes with frequent double flushing (30.8 %) and an about average percentage of homes with high flush volume (23.1%). Both of these toilet models had higher than average rates of flapper leaks. Customer satisfaction ratings for these toilets were below the mean for all toilets (Lamosa Sahara 3.57, 7 toilets; Preserver 3.67, 6 toilets).

Toilets with the tube and bell flush mechanism were rated worst in overall function of all toilet mechanism types. 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%).

The Allegro, which uses a proprietary tube and bell flush mechanism design, had the second highest percentage of homes with high flush volume (40%). It is possible that some homeowners have installed the 3.5 gallon design of this mechanism in their toilets when it was necessary to replace the old mechanism or have modified the 1.6 gallon mechanism. The Allegro had among the lowest customer satisfaction ratings (3.43, 7 toilets).

It appears that toilets with a pressurized flush technology perform best compared to toilets with other flush mechanism types. Pressurized toilets had the lowest percentage of homes with frequent double flushing (9.1%) and the lowest percentage of homes with high flush volumes (9.1%). Pressurized toilets also had the lowest percentage of homes with some low-consumption toilet function problem (35.7%). These results are reflected in the function of the Quantum, which had a small percentage of households with toilets with detectable problems (38.5%), and had the lowest percentage of households with high flush volumes (10%) or multiple flushes (10%). Good pressurized toilet performance also was reflected in the customer satisfaction ratings. All 14 rebate toilets with pressurized flush technology that were still in service were rated as very satisfactory (5).

The percentage of homes with pressurized toilets with some toilet function problem would have been lower, had not some of the pressurized toilets been removed for performance problems. Four Quantum pressurized toilets in 3 households had been removed due to bad performance or lack of available replacement parts. It appears from this limited sample that when pressurized toilets work well, residents are very happy with them, but when they do not perform correctly or need major repairs, residents can be dissatisfied enough to remove them.

Of survey respondents who knew whether or not their toilet had a flapper as the flush valve, 58 percent had replaced the flapper on their rebate toilets. Eighty-five percent of those replacing their flappers had done so by going to a hardware store to get a replacement flapper. The fact that such a high percentage of toilet owners get their flappers from a hardware store underlines the fact that the correct early-close flappers must be available at a hardware store in order for toilet owners to maintain the low-water-use design of their toilets. Production of a standardized early-close flapper that will work with all 1.6 gallon toilets may be necessary to allow hardware stores to efficiently supply the correct replacement flappers for low-water-use toilets.

Use of halogenating in-tank bowl cleaners also has been a factor in flapper performance and durability. The survey revealed that 24 percent of those who knew they had flappers as toilet flush valves used in-tank bowl cleaners. However, no attempt was made to distinguish between halogenating cleaners and non-halogenating cleaners. Tests conducted by MWD in 1994 and 1998 show that some toilet manufacturers are making their flappers more resistant to halogenating compounds. MWD’s recommendations that a warning be included with new toilet packaging about use of halogenating bowl cleaners and a program be established to inform all homeowners about the possible effect of halogenating bowl cleaners on flappers seem appropriate, especially if the finding that a quarter of those with toilets with flappers use in-tank bowl cleaners holds for other communities besides Tucson.