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3.1 Wastewater characteristics (Topic a)

3.1.1 Water supply and sanitation

Across the region, the most significant progress in water supply and sanitation was made in East Asia (People's Republic of China, DPR Korea, Hong Kong, Japan and Republic of Korea). With the exception of the People's Republic of China, the East Asian countries achieved 100 per cent coverage of safe drinking water supply and sanitation in 1990. The People's Republic of China achieved safe water supplies for 87 per cent of its urban population. Other sub-regions have also made great improvements in urban water supply since 1980, particularly in South Asia. However, progress in sanitation has lagged behind, most notably in urban India and Bangladesh. Whilst urban areas throughout the region are now better served with water, sanitation and health services, the urban poor in slums and squatter settlements have generally been overlooked for the reasons mentioned earlier (ESCAP 1993).

The volume of wastewater depends upon water supply coverage and industrial demand. The water supply demand for developed countries is about 250-300 L/person/day, with all of the population having access to water supply service. In the developing countries the water supply demand is about 160-200 L/person/day, with only 60% of the total population having access to an adequate water supply. In urban areas the proportion increases to 90% of the population.

Taking the case of Indonesia, the volume of wastewater introduced to a septic tank system is approximately 160 L/person/day. Typical sources of household wastewater, expressed on a percentage basis are toilet (30 %), laundry (15 %), bath (25%), kitchen (10%) and other (7%) (Caturono et al., 1996).

A survey conducted in Vietnam showed that sewage flows have been calculated on the basis of an average flow of 150 L/person/day, for the year 2015, compared to the long-term water supply demand, which was estimated as 180 L/person/day.

Table 3.2 shows the estimated domestic public water supply and wastewater flows for the different types of cities in Vietnam. Wastewater flows are very uncertain as the flows are not measured in any of the cities. It can be seen that the estimated wastewater flows for the Class I cities (very big cities with population > 3 million) are higher than domestic water supply. This may be explained by the fact that many households are using private water wells and some of these households might also be connected to public sewers. This is particularly common in the South, for example in Ho Chi Minh City (HCMC). The data reveal that water supply is increasing with the city size and that this trend is even stronger with regards to wastewater. Specific wastewater flow is only 39 L/person/day in the Class III cities ( big medium cities with population < 1 million), while Class II cities (big cities with population between 1 million - 3 million) flow is 69 L/person/day increasing to 125 L/person/day in Class I cities. This reflects the fact that a smaller proportion of households with flush or pour flush toilets are connected to public sewers or drains in the smaller cities.

Table 3.2: Public water supply and wastewater flows in Vietnam
  Public Water
water supply
City Class I 200 119 238 125
City Class II 180
87 157 69
City Class III 150 62 93 3

With the rapid development of the economy and continued urbanization growth, the amount of water used for industrial and municipal purpose has been increasing. Total water consumption in China in the late 1960ís was about 476.7 billion cubic meters, of which 57.2 billion cubic meters of water (about 12% of the total amount) were consumed in urban areas and by industries. The quantity of water used for industrial and municipal purposes in 1993 was about 114.3 billion cubic meters (about 22% of the total amount). Industrial and municipal water consumption in China increased by 100% over 15 years (Lin 1999).

Water supply needs in Central Asia in particular are still poorly served. The progress in sanitation is less impressive, particularly in South Asia where less than 5 % of the rural population in Bangladesh, Bhutan, India, and Nepal had access to adequate sanitation by 1994.

Wastewater from industries depends on the type of industry and degree of industrialisation, which varies from country to country. Volume of wastewater produced per industrial establishment in the Asia Pacific countries is generally less than in Europe.


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