The "Ultra-Low-Flush Toilets: Customer Satisfaction Survey," published in December 1999, differed from previous studies in that its sole purpose was to ask customers how happy they were with the toilets.

The MWDSC surveyed 1,300 customers who received 13 different models of low-flow toilets from 11 manufacturers through rebate programs in 1998 and 1999. The highest satisfaction rating of all toilets was an 8.37 out of 10, and the toilet with the lowest rating received a 5.91. More than half of those surveyed reported never experiencing blocking or clogging. However, 67% of respondents said they had to double-flush once or more a month.

Based on overall customer satisfaction, the top five toilets were: the American Standard Cadet 2164.1; the Toto CST703/CST704; the Mansfield Alto 130-160; the Western Pottery Aris; and the St. Thomas Marathon 6201.0.

"We have been benchmarking ourselves and doing our own testing and have concluded that there is essentially no difference in the way current 1.6-gpf toilets flush compared to 3.5-gpf toilets," said Steve Bissell, marketing manager/sanitary products for Kohler Co. "Before the 1.6-gpf mandate, no one really took the time to look at flushing technology. Now that we have been forced to focus on it and have really examined it, I believe we as an industry can now take flushing performance of 1.6-gpf toilets beyond that of 3.5-gpf toilets."

Considering how 1.6-gpf toilets were mandated into existence in 1992, their flushing performance has come a long way, said Lance Nordell, team leader/product development and marketing at American Standard.

"As an industry, we did the best we could in the time frame we were given," Nordell said. "Then we continued to develop products from that point. For example, a lot of complaints about older 1.6-gpf toilets were that the water spot was too small, but now we're pretty close to what they used to be with 3.5-gpf toilets. Also, we changed the hydraulics of getting water into the bowl, altered trapways and did things with jets and gave 1.6-gpf toilets an overall re-engineering since the first generations were introduced."

The American Standard Cadet model referred to in the MWDSC survey, model 2164, is the former Cadet model, Nordell said. Since the introduction of the original Cadet model in 1991, minor performance-enhancing adjustments have been made, followed by a major redesign two years ago.

The Kohler Wellworth model included in the survey was sold from 1989 through 1996, Bissell said. Both the internal and external workings of that model remained the same during those years. The next generation of Wellworth toilets, including improvements to the internal hydrodynamics, was introduced in 1996.

"Overall in the Wellworth line we made an improvement in the trapway size, which was increased by 33%, to reduce the potential for clogging," he said. "We worked on the hydrodynamics of how water flows through the toilet to make it flow better. For instance, the siphon jet primes the trapway and pulls waste down into it earlier in the flush, and provides a strong stream of water to get a good flush, using only the power of gravity."

Customer dissatisfaction with 1.6-gpf toilets led to an alleged black market for 3.5-gpf toilets in Canada. In an attempt to quash HR 623, the Plumbing Standards Improvement Act, which would repeal the 1.6-gpf standard, the president of the American Supply Association told members of a congressional subcommittee to ignore the black market stories.

Harold Williams, ASA president, cited results from a survey of its members in states bordering Canada, in which 92% of those surveyed reported that toilets from Canada were having no impact on product sales in the United States.

"If this rumor were true, plumbing wholesalers along the Canadian border would have seen a drop in their sales, but that has not happened," Williams said.