Phnom Penh’s Municipal drinking water supply: water quality assessment

Sustain. Water Resour. Manag. (2015) 1:27–39 DOI 10.1007/s40899-015-0004-9 ORIGINAL ARTICLE Phnom Penh’s Municipal drinking water supply: water quality assessment Leng Vanny1 • Ge Jiwen1 • Hul Seingheng2 Received: 24 March 2015 / Accepted: 21 April 2015 / Published online: 5 May 2015  Springer International Publishing 2015 Abstract The quality of the municipal drinking water supply for the residents of Phnom Penh, Cambodia is assessed. Based on measurements of water quality for the source water, the treated water and the tap water taken over a 3-year period between 2009 and 2011, the evidence is that the water quality is good and meets both World Health Organization and national drinking water standards. This is despite only basic processes being employed in the water treatment process. This is possible because the source water is of good quality. However, developments in the Mekong river basin pose a number of threats to the quality of the source water. Source water quality degradation in terms of nutrients, heavy metals and pesticides is likely to impact the drinking water quality as the water treatment processes available do not address these species. Keywords Drinking water  Phnom Penh  Water quality  Assessment  Water treatment  Pollution Electronic supplementary material The online version of this article (doi:10.1007/s40899-015-0004-9) contains supplementary material, which is available to authorized users. & Leng Vanny Ge Jiwen Hul Seingheng 1 School of Environmental Study, China University of Geosciences (CGU), Wuhan 430074, China 2 Institute of Technology of Cambodia (ITC), Phnom Penh, Cambodia Introduction Access to safe and clean water is a basic need. The use of unsafe water and improper disposal of human waste, in combination with low hygiene awareness, can result in sickness that prevents people from working and being productive, thus contributing to increased levels of poverty. However, many local authorities in developing countries are unable to provide safe drinking water for some of their population. More than 1.1 billion people in the world, or 15 % of the global population, lack access to safe water (Sobsey 2006). A particular challenge extant in many regions of the world is establishing clean safe drinking water for urban populations following an extended period of war or conflict. This is a particular problem in poorer nations where corruption and lawlessness can complicate the establishment and delivery of a reliable drinking water source. Following, the Khmer Rouge genocide, foreign occupation and years of international isolation the capital city of Cambodia, Phnom Penh in the early 1990s faced such a challenge. This challenge has been met by the Phnom Penh water supply authority (PPWSA) who have in the intervening years been successful in establishing a municipal drinking water supply (Dany et al. 2000). Delivery of supply to a rapidly growing urban population in Phnom Penh and improvements to the water quality have established the PPWSA as an exemplar for other authorities to learn from (Biswas and Tortajada 2010). In Cambodia, securing a safe water supply for the citizens is important for promoting public health and economic wellbeing. For a number of decades, Phnom Penh City had inadequate water quantity and quality and water-related diseases accounted for nearly 30 % of all hospitalizations (UNICEF 2014a). The national targets in the Cambodian millennium development goals (CMDG’s) for improving 123 28 Sustain. Water Resour. Manag. (2015) 1:27–39 access to safe water are different for the urban and rural populations. These goals state that by 2015, the proportion of the population with access to a safe water source will be 50 % in rural areas and 80 % in urban areas: or 58 % as a nationwide average (Thailand MMoNRaEo 2006). Cambodia has already met these targets (UNICEF 2014b), and improvements to the provision of safe water in Phnom Penh have played a significant role in this achievement. The impact that improving access to safe water supply services has had on the health of Cambodians is indicated by the reduction in infant (under five) mortality rate from 115 per 1000 live births to 22 per 1000 live births between 1990 and 2012 (UNICEF 2014a), and this has been accompanied by an increase in access to safe drinking water from 34 % (UNICEF 2006) to 67 % (UNICEF 2014b) of the population over the period from 2002 to 2014. In terms of the water distribution system, unaccounted for water routinely exceeded 80 % during the late 1980s, and the pressure of water was so low that most households received no supply, even though they were connected to the system. However, since then significant improvements have been implemented (Biswas and Tortajada 2010). During the 15-year timeframe between 1993 and 2009, the annual water production increased by over 400 %, the distribution network by over 500 %, water pressure in the system by a factor of 12, and the customer base by a factor of six. Unaccounted for water reduced from 72 to 6 % (Biswas and Tortajada 2010). Table 1 summarises the state of the water supply in 1993 and 2009 and illustrates the substantial improvement the citizens of Phnom Penh have experienced in regard to access to water. Cambodia had no water quality standard for drinking water until the late 1990s when the PPWSA changed the parameters being monitored and adopted water quality standards from the World Health Organization (WHO). The successes of the PPWSA in establishing an effective water supply to a rapidly growing city in a poor country emerging from war and decades of neglect with endemic corruption (Un 2005) are worthy of attention as similar challenges are faced in many cities where stability has emerged and infrastructure for growth and development is being implemented. Table 1 Phnom Penh’s expanding water supply (PPWSA 2014) 1993 Indicators 2009 65,000 m /day Production capacity 300,000 m3/day NA* 20 % Water quality Coverage area WHO 90 % 10 h/day Supply duration 24 h/day 0.2 bar Supply pressure 2.5 bar 26,881 Number of connections 191,092 3 123 This paper reports on the water quality of the source water, the treated water and the tap water for the municipal water supply of Phnom Penh, the capital city of Cambodia. Relationships are investigated between the water quality of the source water and the water quality of the municipal supply with a view to understanding how the system may be improved, to anticipate challenges to future water quality. Materials and methods Currently, Phnom Penh has three water treatment plants (WTP) and each draws its water from a different source. The Phum Prek WTP supply is taken from the Tonle Sap near Phnom Penh Port. The Chamkar Mon WTP supply uses the pump station located near the Thai Embassy along the Tonle Bassac, and Chrouy Changva WTP pump station is located along the Mekong river. The locations are shown in Fig. 1. The combined capacity of t (...truncated)