Under the 'Swaachh Bharat' programme, household sanitation coverage increased at a rate of 13 per cent annually between 2016 and 2018, WHO said.
Everyone should have access to safe sanitation facilities including hygienic toilets that are connected to quality sewage systems, WHO said, adding that for many people in its South-East Asia region, as across the world, access to these services remains a problem.
WHO Regional Director for South-East Asia Dr Poonam Khetrapal Singh said 900 million people region-wide lack basic sanitation and more than 500 million practise open defecation.
Singh said that in recent years, member states have made significant progress and region-wide urban coverage of basic sanitation is now close to 70 per cent.
In a majority of countries, rural coverage exceeds 50 per cent and the share of the region's population practising open defecation has been reduced from more than 50 per cent to less than 30 per cent, while several member states have achieved more than 90 per cent coverage of basic sanitation services.
These advances are to be commended and they must also be built on, she said, adding that the return on every dollar invested in safe sanitation is estimated to be nearly six times increased productivity and fewer premature deaths.
"All people everywhere should have access to safe sanitation services, including hygienic toilets that are connected to quality sewage systems.
"For many people across the WHO South-East Asia Region, as across the world, access to these services nevertheless remains a problem, with 900 million region-wide lacking basic sanitation, and more than 500 million practising open defecation," Singh said.
"This leads to increased human-feces contact and transmission of a range of diseases, from cholera to typhoid and hepatitis A and E to tapeworm," she said on the eve of World Toilet Day.
WHO's South-East Asia Region comprises Bangladesh, Bhutan, Democratic People's Republic of Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste.
As outlined in WHO's recently launched Guidelines on Sanitation and Health, there are several ways member states can sustain their many gains, accelerate progress and make safe sanitation services accessible to all, she said.
"First, health authorities should work across sectors to ensure all communities have access to toilets that adequately contain excreta. Of key importance is targeting communities in hard-to-reach areas, as well as those living informally in cities or urban zones.
"India's Swaachh Bharat campaign is a good example of how this can be done to rapid effect and on a large scale, with household sanitation coverage increasing at a rate of 13 per cent annually between 2016 and 2018," Singh said.
Secondly, authorities should ensure all toilets are connected to services that provide safe sewage treatment and disposal, she said.
This means conducting health-risk assessments of sanitation systems on an ongoing basis, with issues or gaps remedied as a matter of priority. It also means engaging planning authorities at the local level to ensure this process is sustainable and that the environment remains free of human waste, Singh said.
"And third, health facilities themselves must provide safe and functional water, sanitation and hygiene services.
"Region-wide, too, many facilities still lack these basic services, representing a missed opportunity to drive down health care-associated infections, reduce the length of hospital stays and decrease maternal and newborn deaths among other benefits," she said.
Singh asserted that WHO is committed to supporting member states as they strive to make toilets and safe sanitation services accessible to all.
"Doing so will help achieve several of the region's own flagship priorities, as well as the wider sustainable development agenda, including sustainable development goals 3 and 6 (on health and sanitation respectively). Indeed, as World Toilet Day highlights, the benefits of access to toilets and safe sanitation for all are many and must be harnessed to maximum effect," she added.