As a professional engineer and engineering consultant, John Koeller, PE, principal of Koeller & Co., loves to solve problems and address issues related to water use efficiency and conservation. For the past 30 years, he’s been doing just that.

However, he didn’t start his engineering path in that sector. For the first 20 years (from 1973-1993) of his 50-year career, Koeller did environmental work in the United States for organizations such as the Army Corps of Engineers and private sector businesses.

In 1993, he switched career paths and moved into the water conservation and efficiency realm. 

The move was motivated by a session on water he attended, which materialized into some water conservation and efficiency business. Simply put, “I found it fascinating,” Koeller says.

For one of his first projects, he was contracted by the Metropolitan Water District of Southern California to oversee its toilet replacement program from 1993 to 1998. This involved the distribution of free, more-efficient toilets to address the drought issue in the region. The program intended to reduce water demands by replacing toilets using 3.5 gallons or more of water per flush with toilet fixtures that used no more than 1.6 gallons per flush, as mandated by California and the federal government’s enactment of the Energy Policy Act of 1992.

The program involved purchasing and distributing up to 25,000 two-piece, 1.6-gallon toilets a month, which were given out to residential customers around Southern California.  “Unfortunately, we later began receiving comments from a number of program participants complaining of poor flushing performance and, at that point, we realized we had purchased a lot of marginal product,” Koeller recalls.

As Koeller explains, people didn’t call the manufacturer to complain about the toilets; instead, they called the water utility that provided them. So Koeller and his team gathered some of the major water utilities together at an American Water Works Association meeting and informed them that a better system needed to be developed for measuring performance for flushing and leakage of the toilets being manufactured at that time. And that’s how Maximum Performance Testing (MaP) was born.

In 2002, Koeller partnered with Bill Gauley, P.Eng, principal at Gauley Associates in Canada, to obtain funding from 22 water utilities in the United States and Canada and develop a program to test and rank toilet models for efficiency and flush performance.

“The water utilities commissioned us to develop a test that was more reflective of the real world than the certification test in the national product standard,” Koeller says (see sidebar). 

The Evolution

Koeller and Gauley’s first MaP test report was released in 2003, revealing that half of all models tested failed the minimum 250-gram threshold for flushing waste. 

“We thought that was the end of it,” Koeller notes. However,  the manufacturers whose toilets came out as poor performers said, “We can do better. If you test the new and improved toilet models we will bring into the marketplace, will you revise your report?” Of course, the answer was “Yes.” As a result, the manufacturers developed hundreds of better-performing toilet models and almost all were MaP-tested.

Initially, toilet models were MaP-tested at Gauley’s laboratory in Mississauga, Ontario, Canada, but it soon became apparent that it made more sense for new toilet models to be MaP-tested at the same location where they were being certified. Currently, 11 accredited laboratories in North America and Asia perform MaP testing. 

When testing occurs, the results get sent to Koeller and Gauley, who report the flush performance results on on their website www.map-testing.com. 

“We post test results on our website and consumers can get the information free,” Koeller explains. “Water utilities can also use the information to create rebate programs. We’re the intermediary for communications purposes, you might say.”

Twenty years later, MaP testing is an ongoing process. Koeller and Gauley recently agreed to test products from their 189th manufacturer. “We have the flush performance results of well over 5,000 fixture models in our database; all of those results are freely available to the public,” Koeller says. 

“Our website has posted a lot of information over the last 20 years to help the public make smart purchasing decisions,” he adds. “However, the MaP program also has encouraged manufacturers to improve their products. Now, most of the products on the market perform exceptionally well. Some manufacturers were able to design a toilet to remove as much as 1,000 grams of soybean paste in a single flush. If you ever saw 1,000 grams of soybean paste, you’d be amazed any toilet could flush it. That, to me, was our contribution to the plumbing industry.”

Where We Are At Today

Today, the American Society of Mechanical Engineers/Canadian Standards Association’s national product standard for a conventional toilet specifies a maximum water use of 1.6 gallons/flush; many states now mandate less — 1.28 gallons. That number stemmed from the Leadership in Energy and Environmental Design program’s initiative years ago to reduce water consumption by 20%.

However, it didn’t stop there for the MaP team. About seven years ago, it began identifying toilets that could perform as well with even less water — flushing at least 600 grams of waste while using no more than 1.1. gallons (4 liters) per flush. “We’d seen a lot of four-liter toilets that worked very well, and Gauley’s 2005 drain line transport study found those lower-volume toilet models would work satisfactorily in typical residential dwellings,” Koeller notes. As a result, the MaP PREMIUM designation was created for those models.

The team took that information to the water utilities, which motivated many of them — including utilities in California, Denver, Seattle and Atlanta — to change their rebate programs to only rebate MaP PREMIUM toilets. 

“We currently identify more than 400 PREMIUM toilet models that meet those more rigorous requirements and are on the rebate lists in those regions,” he adds. (To see the list, visit www.map-testing.com/map-premium.) 

Incidentally, Koeller and Gauley are under contract for work on the Environmental Protection Agency (EPA) WaterSense program and the California Energy Commission Title 20.

“We believe we have significantly influenced the improvement of toilet flush performance and other factors over the past 20 years,” Koeller says. “Because of MaP testing and the competitive nature of the industry, many manufacturers were strongly motivated to engineer better-performing toilet models flushing with only 1.28 or 1.1 gallons/flush.” 

Current Government Initiatives

In June, the EPA announced that it is considering revising the WaterSense Specification for Tank-Type Toilets (https://bit.ly/3L12hbN), most recently updated in 2014. As a result, it is looking to reassess flush volume requirements, including the criteria for dual-flush systems to reduce the maximum allowed flush volume on the dual-flush toilet from 1.6 gallons to 1.28 gallons. 

Dual-flushing toilets were developed to save water by allowing users to select a lower flush volume to remove liquid waste. If, however, users always choose the full-flush volume – which can be as much as 1.6 gallons – there is no water savings and, in fact, the toilet would use more water than a typical single-flush 1.28-gallon fixture, Koeller says. As such, it seems logical to remove the 1.6-gallon option for dual-flush models.

Expanding Water Use Horizons

When asked his opinion on what has been the most significant milestone in the plumbing industry over the last 50 years, Koeller says: “Significantly reducing water consumption of water-using fixtures and fixture fittings while still providing consumer satisfaction was shown to be possible. The plumbing industry stepped up to reduce water consumption without sacrificing user satisfaction.”

What the future holds is unknown, but Koeller believes the focus will be on new products that expand the horizon in terms of water use and water efficiency. In his opinion, this includes leak detection equipment and systems, humidifiers and evaporative cooling (including cooling towers).

He also foresees initiatives in the green building and design community to flush toilets with treated greywater or other nonpotable water. “However, there is some conflict between what you deliver for a toilet flush versus for a bidet seat; that is, between treated greywater versus potable water.”

Koeller foresees the biggest impact on water use and water efficiency will come from improving outdoor water use. “The focus is already shifting away from indoor, recognizing that you can go only so low and you can’t go much lower without risking affecting the function of the wastewater systems. Outdoors, there’s a huge opportunity for water savings by whatever means — efficient irrigation, no irrigation, xeriscaping or turf removal.”