They flushed smashed bananas. They flushed mashed potatoes. But the two engineers soon discovered that the best method for testing a toilet’s flushing ability was soybean paste. Its consistency was perfect.

And so Bill Gauley and John Koeller have used soybean paste, also known as miso, for almost two decades to test toilets, part of their carefully calibrated protocol that has become a common testing standard throughout the toilet industry.

The two men say today’s toilets are flushing marvels, able to clear an average of two pounds of paste and paper per flush — more than just about anyone needs, and four times as much as old commodes, despite using less than half as much water.

So Gauley and Koeller were surprised when President Trump recently started complaining publicly about toilets. “People are flushing toilets 10 times, 15 times, as opposed to once,” Trump said at the White House last month. He also talked about toilets during a rally in Milwaukee two weeks ago.

The comments were among a recent barrage of presidential complaints about the allegedly declining performance of common household items, including dishwashers (“Now you press it 12 times. Women tell me. . . . You know, they give you four drops of water.”) and shower heads (“You turn on the water. Drip, drip, drip.”) and lightbulbs (“Costs you five times as much, and it makes you look orange.”).

Trump blamed government efficiency standards, which he indicated he planned to gut.

But Trump’s frequent allusions to a bygone era filled with superior appliances misses what is largely a story of American ingenuity and continued progress.

Several manufacturers and trade groups said these items work better than ever today — while also using less water and power, the result of years of corporate investment and testing. Industries that might normally cheer reduced regulation say they don’t want government efficiency standards eased.

The one exception: a trade group for electrical equipment manufacturers, which welcomed the administration’s decision last fall not to enforce a stronger standard for lightbulbs. That decision upset environmental groups, which say the move will allow for the continued use of energy-wasting incandescent bulbs.

The makers of dishwashers, toilets and shower heads say their objections to weakening government regulations should be viewed as a success story.

“Ripping out all that regulation, from my standpoint, seems pretty wasteful,” said Kerry Stackpole, executive director of Plumbing Manufacturers International, a leading trade group. “We’re not hearing lots of complaints about showers and shower heads.”

Julie Wood, senior director of corporate communications at GE Appliances, said in a statement: “We are not in favor of unlimited water and energy use for dishwashers.”

“I can’t imagine what [Trump] was talking about,” said Koeller, the co-founder of Maximum Performance Testing, an independent tester of most toilet brands sold in North America. “We know what the real world is. And it’s not close to what he claims.”

White House spokesman Judd Deere said in a statement that Trump believes in eliminating “harmful, burdensome, and unnecessary regulations.”

Deere added that the president has “unleashed the American economy, provided greater regulatory certainty, given consumers more choice, and continued to safeguard the water supply and improve air quality.”

The efficiency standards targeted by Trump were mostly passed under the Republican administrations of Ronald Reagan and the Bushes. Global warming was less of a concern back then. The rules were often in response to rising utility bills and a patchwork of state laws.

The first bill to deal with major appliances was vetoed once by Reagan before Congress passed it again in 1987, including by an 89-to-6 vote in the Senate, thanks to a coalition of manufacturers and conservationists.

Trump’s attack on efficiency standards has been encouraged by outside groups, such as the conservative-leaning Competitive Enterprise Institute, which in March 2018 asked the government to allow for a new, faster class of dishwashers. The goal: a cycle time under one hour.

Sam Kazman, the institute’s general counsel, who helped draft the petition, blamed tighter water and energy regulations for slower dishwashers. The average cycle time jumped from 70 minutes in 1983 to about 140 minutes in 2018, according to the petition’s calculation of Consumer Reports data.

“They take a long time and they do not do as good a job as they used to,” Kazman said in an interview.

The petition is so far a success. It garnered more than 3,000 comments, many of them supportive, such as the one that offered, “Please make Dishwashers fast again.” The Energy Department said last year it would consider the petition’s suggestion.

Kazman, who noted his displeasure with a new dishwasher he recently purchased, said he was initially surprised by manufacturers’ objections to his petition.

“But they have investments that they need to protect,” Kazman said, “and the fact is that those investments are compelled by overregulation.”

But the Association of Home Appliance Manufacturers said the petition aims to solve a problem that doesn’t exist. The trade group wrote a letter responding to the petition, saying that while its members “appreciate the sentiment,” the group didn’t see a need for a new class of dishwasher. Many consumers already have one, they said: Almost all dishwashers shipped in 2017 came with a faster-cycle option that got the job done in under an hour, on average.

“The point is that, at this point in time, energy efficiency need not be sacrificed to achieve maximum consumer satisfaction,” the trade group wrote in its response.

Consumer Reports said its testing data didn’t show signs of weakening performance by modern dishwashers. A change in the advocacy group’s methodology makes absolute comparisons across decades difficult. But, Consumer Reports said, about a quarter of the 150 dishwashers it recently tested earned an “excellent” rating — what a spokesman described as “impressive.”

Trump’s complaints about shower heads deal with a change made 25 years ago. Shower power was cut by federal regulations in 1994 to 2.5 gallons per minute, down from 3.5 or higher. Several states, including California and Colorado, cut that to two gallons or lower.

At first, manufacturers struggled to produce a product that consumers liked, said Stackpole, of Plumbing Manufacturers International.

“It’s like any new invention,” Stackpole said. “When you first start out, it’s a little bumpier. Like with software.”

But companies experimented with different diameters and tighter nozzle heads. They added adjustable sprays. The biggest problem today, Stackpole said, is low water pressure from pipes feeding into a home. That can produce an unsatisfactory shower, no matter the shower head.

Flushing toilets with less water seemed like a harder problem to solve. Federal laws in the mid-1990s set a limit of 1.6 gallons per flush. Toilets had allowed 3.5 or even 5 gallons per flush.

Gauley and Koeller — who both previously worked on water-efficiency projects — founded Maximum Performance Testing because they noticed that some toilets performed well while others struggled. And it wasn’t always related to water use. Consumer surveys showed that some old 3.5-gallon toilets rated worse than low-flow toilets.

The protocol devised by these two men also tests for WaterSense, a voluntary certification program created by the Environmental Protection Agency that certifies performance in toilets that use 1.28 gallons per flush or less.

They learned over the years how to make better toilets.

“It’s not rocket science,” Gauley said modestly.

Their test requires a toilet to clear 350 grams of waste — that’s about three-quarters of a pound — in a single flush. They settled on that number because, as Gauley explained, it represents the 99th percentile of what a healthy man can produce in a single sitting.

The soybean paste is squeezed through a tube into narrow segments, each four inches long and weighing 50 grams. The segments are dropped through a guide, just above the rim, to simulate real-world experiences. A toilet must clear seven of them, along with four balls of precisely six sheets of toilet paper, to pass.

But toilet trouble is increasingly a thing of the past. Designs have improved. The engineering is solid.

Last year, the average toilet they tested — including some that used much less than 1.6 gallons — cleared 895 grams of waste, or almost two pounds. That’s 17 paste segments.

“If you could see what 895 grams looks like, you’d be shocked,” Koeller said. “It’s huge.”