Filthy toilets remain a blight across Asia despite rising standards of living, with dire effects on poverty reduction and public health.
Social activists say dismal sanitation facilities are causing preventable diseases in poor communities where people would readily spend money on a mobile phone -- but not on a latrine.
"I think it's very prevalent," said Jack Sim, a Singaporean businessman who founded the sanitation advocacy group World Toilet Organisation. "The handphone is the competitor of the toilet."
US business magazine Forbes says Asia now has the second largest population of billionaires worldwide at 332, behind the United States' 413 while leapfrogging Europe's 300.
But in Asia's teeming urban slums and impoverished villages, toilet facilities are either non-existent or rudimentary.
"The lack of good toilets as well as sanitation is still a problem in Asia," said Babar Kibir of Bangladesh-based BRAC, one of the world's biggest non-government organisations.
Sanitation has an "immense effect" on poverty reduction, Kibir said.
"It has linkages with poverty, child mortality, combating disease and environmental sustainability," the director of BRAC's Water, Sanitation and Hygiene Programme, or WASH, told AFP.
People living in poor sanitary conditions are vulnerable to illness which often prevents them from finding regular employment, Kibir said, adding that much of the meagre income they earn would be spent on medical treatment.
Diarrhoea, malnutrition, arrested physical growth, loss of eyesight, typhoid, dysentery and hepatitis are diseases commonly associated with poor sanitation.
"Poor people, particularly women and children, can enjoy protection from diseases, malnutrition and death by using safe water and sanitation facilities including improved hygiene practices," said Kibir.
Singapore's Sim said charity alone cannot help solve the problem of an estimated 2.5 billion people worldwide without access to proper sanitation.
Businesses, governments, banks, micro-finance institutions and NGOs must band together to create a business model that can offer affordable and sustainable toilet systems to the poor, he said.
Sim, organiser of an annual conference called the World Toilet Summit, estimated the global market for sanitation hardware at one trillion dollars.
"I hope that the commercial sector comes in... We need to go to scale, we need to see this as a wonderful business opportunity."
In Bangladesh, one of Asia's poorest countries, BRAC's WASH programme provides micro-loans to the poor to build toilet facilities, charging only a minimum service charge. Grants are given only to the very poor.
But the programme goes beyond just providing latrines -- it comes as an entire package, which includes designing and building eco-friendly toilets and raising awareness in the community about the need for good sanitation.
Men, women and adolescents are taught good hygiene practices, while local community and religious leaders and micro-credit groups are roped in to help instil the message, Kibir said.
Sim said some aid agencies focus on building toilets but neglect the education part.
"They want to count how many toilets they have given, but they are not counting how many toilets are being used," Sim said.
People should be taught that a good toilet is an "aspirational goal" that can boost self-esteem and social standing, apart from improving health -- and toilet bowls could even be given as wedding gifts, he said.
Citing Japan's impeccably clean toilets, Sim said: "The peer pressure is there -- that when you don't have a clean toilet, you are shaming your company, your building, your country, your community.
"The toilet tells a lot about the culture of the people. They can be carrying Louis Vuitton handbags but if their toilets are so dirty that shows they are still an immature society, they're still not sophisticated, not elegant," Sim said.