More than 140 million people in South-east Asia lack access to safe drinking water, while nearly a billion have no access to basic sanitation, according to official figures last year.
Regional governments need to put in more effort to provide safe and sustainable water and sanitation services, particularly to rural areas, according to the latest United Nations Water Global Analysis and Assessment of Sanitation and Drinking Water report, released by the World Health Organisation.
Countries in the region face geographic and economic inequalities in access to water and sanitation.
Even where national strategies are well-developed, government institutions are well-coordinated and sufficient financing is available, several countries report a shortage of workers with the relevant skills to effect changes.
The shortage is due to inadequate educational facilities and recruitment practices, added the report.
In Indonesia, more than 32 million of its 257.6 million citizens lack access to safe water and nearly 101 million lack proper sanitation, according to a World Bank report last year.
In Jakarta alone, only about 40 per cent of its 10 million residents have access to piped water for cooking, last year's official data from the Central Statistic Agency showed.
More than a third (36 per cent) of the population in the city still use artesian wells, while 15 per cent use bottled or refilled water. Surprisingly, almost 8 per cent of those living in Jakarta still rely on rainwater.
In rural areas, poor villagers are highly susceptible to diarrhoea and other water-borne diseases as water from wells or spring water is not properly treated.
Even if the water is boiled, it is stored in dirty pots and pans.
The current government, however, plans to raise the population's access to clean drinking water by 30 per cent and basic sanitation access by 40 per cent by 2019.