"When it comes to testing toilets, it turns out the appropriate substitute for human feces is miso paste. That's what EPA uses to ensure that commodes earning its WaterSense efficiency label flush effectively.
To earn the label, tank-type toilets currently must use 1.28 gallons or less of water per flush while eliminating 350 grams of miso paste, along with toilet paper.
That may be news to President Trump, who last week complained that low-flow toilets were not getting the job done, so 'people are flushing toilets 10 times, 15 times, as opposed to once.'"
Source: Greenwire, 12/16/2019