After killing its lifeline, the Bagmati, Kathmandu valley is extracting its groundwater to the last drop. But the quality of groundwater here is fast deteriorating due to lack of proper sewage disposal system and years of overexploitation, warn analysts.
This is dangerous. In the absence of adequate water supply, almost every household in Kathmandu has either a borewell, a hand pump or a dug well. Some also depend on hittis, a traditional shallow groundwater source. Even the water supply authority, Kathmandu Upatyaka Khanepani Ltd (KUKL), depends on groundwater for up to 35 per cent of the water it supplies.
Lately, increasing cases of water-borne diseases like diarrhoea, typhoid, Hepatitis A and E are being reported from areas where people depend on supply water or groundwater, says Razni Malla, associate professor at the microbiology department of Tri Chandra University in Kathmandu. “This indicates microbial contamination in supply and groundwater,” says Shova Srestha, head of the department. The diseases are common among slum-dwellers who depend on shallow hand pumps situated close to drains or dump yards.
A study by non-profit Environment and Public Health Organisation (ENPHO) corroborates the observations. The study, which analysed groundwater across the valley, found over 80 per cent of the samples contaminated with E coli. Worse, the study found high concentrations of ammonia and iron in the groundwater of central valley. About 85 per cent of the samples had ammonia content above the WHO limit of 1.5 ppb (parts per billion) in the pre-monsoon period. Iron concentration in 97 per cent of the samples was above the WHO limit, says Narayan Prasad Upadhyay, technical advisor of ENPHO.
| Extent of groundwater pollution
- 80 per cent of groundwater samples from central valley had E coli
- 50 per cent of the deep tube wells in Kathmandu and Lalitpur municipalities contained arsenic much above the WHO standard
- 85 per cent of the groundwater samples from central valley had ammonia above the WHO limit
- 97 per cent of groundwater samples from the central valley had iron above the WHO limit
Source: Surveys by EMPHO |
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“Iron and ammonia are present in groundwater in certain pockets of the valley due to geological reasons,” says Suresh Das Sreshtha of non-profit Centre for Integrated Urban Development (CIUD). According to Shashank Shekhar, assistant professor in the Department of Geology, Delhi University, high concentration of iron and ammonia could be because of overextraction of groundwater. Concentration of ammonia can also increase because of sewage contamination, he adds. High concentration of iron turns water reddish brown leaving stains on clothes. Ammonia imparts foul smell to water, making it unfit for drinking. “When chlorinated, ammonia produces poisonous chloramines,” Sreshtha adds.
An earlier study by ENPHO had found that about 50 per cent of the deep tubewells in Kathmandu and Lalitpur municipalities had arsenic concentration much above the WHO standard.
Higher arsenic concentration in deeper aquifers and the presence of coliform bacteria in shallow aquifers complicates the situation. To deal with the situation, Nepal’s ministry of physical planning and works has prepared a policy of rainwater harvesting, which, it claims, will take care of the quantity and quality of groundwater.
The government has introduced a licensing system to stop rampant extraction of groundwater. CIUD has launched “Recharge Kathmandu campaign” for dilution of natural contaminants in groundwater. But these steps may not be enough unless the government introduces proper planning of sewage disposal in the Bagmati Action Plan, which is scheduled to be implemented in 2015, says Prakash Amatya, former executive director of CIUD. The government should also map arsenic-safe zones and manage groundwater sources, experts suggest.
