Perhaps no one takes all this more seriously than Jack Sim, a Singapore businessman who in 2001 founded the World Toilet Organization.
Its World Toilet Summit has met annually in many cities since then - in Moscow, a visit to the space station toilet was a highlight - and in early November it made its U.S. debut by teaming up with a plumbing convention in Philadelphia.
Mostly, the summit was about public toilets, which are ripe with issues.
Are they safe enough, accessible enough, green enough, clean enough? Are there enough to begin with?
The universal answers: No, no, no, no, and definitely not!
Furthermore, public facilities lack privacy. Europeans and Asians are appalled at how high most American stall doors are, leaving a person's legs and possibly even underwear on display.
There is little gender equality. Women still have to wait in long lines while the men sail through, although a bill to address the imbalance in federal buildings has been introduced in Congress. Although it's unlikely to move, "this is the highest level potty parity has gotten to," gushed Kathryn H. Anthony, a University of Illinois architecture professor. "It's historic."
When the summit organizers picked Philadelphia for their first U.S. conference, they were coming to an area rich in toiletry.
Benjamin Franklin was an early adopter of the flush toilet, and while his no longer exists, visitors to Franklin Court can still see his privy.
Fast-forward to 2006. The city became infamous for the plumbers union battle over installing waterless urinals in the Comcast Center.
Philadelphia also may well be the first large city in the United States to have public composting toilets. Two are in Fairmount Park along the Wissahickon, and one was installed weeks ago along the Schuylkill at Walnut Street.
Plenty of people, it turns out, care deeply about toilets.
Bill Chapman, founder of the Australian Toilet Organization, visits restrooms worldwide, counting urinals and toilets, sniffing for odors, noting whether the hand dryers are strategically located.
Chicago's Nancy Klehm is an under-the-radar activist whose Humble Pile "urban nutrient-recovery project" involved collecting the excreta of her neighbors, composting it for a few years, and then returning it as fertilizer. Tests confirmed it contained no bacteria, she said.
"By embracing our bodies as soil-makers, we can start healing our city soil," Klehm said. There's a new term for it: humanure.
Marian Loth of the Netherlands invented a urinal for women called the "Lady p." - not yet a market success - and is working on her doctorate, studying toilets on trains. (So no need for her to bother riding SEPTA's commuter trains, which have none.)
Georgia's Tom Keating, a self-described "toileteer," has made public schools his stomping grounds. He contends that 40 out of 100 students never use the bathrooms. They're nasty. They have no doors, no paper. They're the turf of bullies.
"I call that a national disgrace," Keating said. How can we have compulsory education, yet, once the children are there, make it all but impossible for them to use the bathroom? He estimates that at least a fifth of school bathrooms need improvement.
Outside the developed world, a lack of toilets is a leading cause of illness, which affects education and productivity. UNICEF estimates that proper sanitation would reduce deaths from diarrhea by 32 percent.
Sim sees this as not just a public-health travesty, but one of the best business opportunities going. "One billion of anything is a lot to sell," he told the plumbing conference in a keynote speech.
People in poorer countries can afford cell phones. Why not toilets?
Friday's World Toilet Day will be marked by such events as the "Big Squat," where people worldwide will be asked to squat for one minute - preferably in public, although as a simulation only, please - to champion those who don't have access to sanitation.
But it's tough talking about this stuff. People keep giggling. Or blushing.
To bring toilets "out of the water closet," Sim and other advocates often go for shock value, tossing in the "s" word.
A more polite strategy comes from the U.K.'s Loo of the Year Award.
Judges consider about 100 criteria, from whether there's an odor to whether there are disposal facilities for "nappies."
Last year, among 1,548 entries, the big winner was that American icon: McDonald's.
Many say the modern flush toilet is - or should be - obsolete. We take a substance that has nutrient value, add drinking water and paper, pipe it long distances, and then use huge amounts of energy to treat it.
As such, composting toilets are gaining new appreciation, fueled by concerns about water shortages and the decline of agricultural soils.
"We are standing at a fork - the toilet as the root of environmental pollution, or as a gateway for resource reclamation," said Imai Shigeo of the Japanese sanitary-fixture manufacturer INAX.
But for most of the Western world, it's all about the flush.
"In the U.S., we're better off trying to get 99 percent of the people to have a toilet that uses 30 percent less water than coming up with a toilet that uses 99 percent less water that only 1 percent of people will adopt," said James McHale, a vice president of the American Standard bathroom-fixtures firm.
Until 1992, most toilets used 3.5 gallons of water or more per flush. That year, federal legislation lowered the maximum amount to 1.6 gallons. The U.S. Environmental Protection Agency encourages more conservation by limiting the flush to 1.28 gallons for a toilet to get a "high-efficiency" rating.
The holy grail is 1 gallon or less - all without compromising on performance. (Meaning no clogs, no leftovers.) What good is a low-flush toilet if you keep flushing?
On the exhibition floor of the plumbing conference, toilet manufacturers were showing off their best.
The typical person is a 250-gram "performer," said American Standard's Mike Friedberger. (That's just over half a pound.) But in the quest to keep the plunger idle, most toilets are built to accommodate 1,000 grams.
Any more, Friedberger said, and "you don't need a toilet, you need a doctor."
New on the U.S. market - although common in Europe - is the dual-flush toilet. Users push one button for a small flush, which is usually around a gallon. The larger button gives a full flush.
At the Japanese company Toto, toiletry was also about luxury.
The company is working on surfaces that are so smooth they rarely need cleaning.
Toto's "Washlet," a state-of-the-art seat starting at $800, has a heated surface. A small, extending wand acts like a mini powerwasher, with both the water temperature and pressure adjustable.
A dryer finishes the job.
It has a deodorizer.
"We say that once you use it," said Toto executive Chris Ehlers, "you'll never go back."
Contact staff writer Sandy Bauers at 215-854-5147 or firstname.lastname@example.org. Visit her blog at http://go.philly.com/greenspace