With growing urbanisation, industrialisation, agricultural and other anthropogenic activities, fresh water resources such as rivers, lakes, streams and ground water — are being depleted. Besides, these water resources are being contaminated with toxic metals, hospital waste, pharmaceuticals, agrochemical wastes, etc. The deterioration in water quality causes serious illnesses including typhoid, cholera, hepatitis A and E, polio, dysentery, etc., through waterborne bacteria, viruses and protozoa, while water-related diseases like malaria and dengue fever spread due to environmental pollution.

The quality of water is greatly affected by open drainage system in urban and peri-urban areas of the country. Household open drains are allowed to flow into water sources, recharging ground water and spreading ground water pollution.

The Pakistan Strategic Country Environmental Assessment Report (PAK-SCEA) 2006 says that approximately 2,000 million gallons of sewage is being discharged to surface water bodies every day. Human and animal waste including agricultural wastes are thrown directly into surface water resources like dams and nullahs passing though the main cities causing serious threats not only to agricultural soil but also to ground water and human health. According to reports 20-40 per cent diseases in Pakistan are related to water pollution and contamination of water resources.

Water management and open drainage system is a continuous challenge. For instance, Nullah Lai in Rawalpindi is heavily polluted with litter and untreated wastewater; it receives latrine effluents directly spreading environmental pollution along with surface and ground water pollution.

A need to minimise the impacts on water resources and health

According to Water and Sanitation Authority (WASA), Rawalpindi (east zone) alone produces about 44 million gallon per day of sewage. There is no sewage treatment at Rawalpindi and all the sewage is disposed into Nullah Lai through piped and open drains. More than 1,000 tonnes of garbage and construction material is deposited in the Lai Nullah on a daily basis. Some tube wells installed beside the Lai and water wells in the houses used for drinking and other purposes are recharged by the contaminated sewage and infiltration of contaminated water.

Numerous environmental hazards are also associated with open drainage including ground water contamination, impact on disease burden, decrease in soil productivity, contamination of vegetables and crops grown with wastewater become contaminated with pathogens become unhealthy for human consumption especially when consumed in raw form. Sometimes, these foul-smelling open drains originate from individual houses and join the big drain and fall ultimately into the rivers or informal settings.

A humid and warm weather promotes the growth of microbes in polluted environment. Change in climatic conditions (rainfall pattern, temperature and moisture) especially in the monsoon causes increase of dengue fever, diarrhoea, typhoid and cholera. Pollution also causes spread of malaria and is accountable for breeding places for Aedes aegypti (The insect does not survive at temperature below 5oC) spreading dengue virus in the country. Although vulnerability against dengue fever has declined in 2015 due to awareness campaigns among the general public and educational institutions by the provincial and local government, there is however, a strong need to control the breeding places and marshes providing habitat for reproduction of water related parasites which can be prevented by controlling open drainage. Hepatitis A and E spread through contaminated water along with other reasons and can be prevented by using safe food, contamination-free water and by adopting better sanitary conditions.

Beat Stauffer, a journalist and a graduate of environmental engineering with a focus on water systems, in 2012 compiled an article “Open channels and drains” published by Sustainable Sanitation and Water Management (SSWM) which suggested many alternate methods like septic tanks, constructed wetlands and biogas settlers. He further described cost analysis, advantages and disadvantages of the open drainage system. Certainly, there is one time cost for the development of infrastructure and septic tanks for drainage system but that will decrease the high- risk related to open drainage system. Design is one of the technical requirements and it should be large enough to carry the wastewater and proper flow.

A humid and warm weather promotes the growth of microbes in polluted environment. Change in climatic conditions (rainfall pattern, temperature and moisture) especially in the monsoon causes increase of dengue fever, diarrhoea, typhoid and cholera.

To mitigate open drainage impacts on environment and water quality, development of waste water treatment and proper solid waste management systems are of immense importance. The treatment should be safe, environmentally acceptable, technically and economically feasible. Permeable pavement system (PPS) can be one of the solutions for sustainable drainage system and provides onsite treatment of surface water, increase infiltration, reduce urban and rainfall runoff. PPS can be combined with water recycling technology and treated water can be used for car washing, gardening and flushing toilets.

Harvested rain and flood water may be utilised for groundwater recharge to compensate the anthropogenic influences. There is a need for sustainable urban drainage system to encounter the climate change challenges and population growth influence. Drinking water pollution is a serious threat to human health and need urgent attention of policy makers and government authorities.

According to the National Sanitation Policy, the government set the target to reduce the proportion of people without access to sanitation and safe disposal of liquids to 50pc by 2015 to meet the Millennium Development Goals but failed to achieve the goal. There is a need to increase budgetary allocation for safe water supply and sanitation schemes. Without significant adaptation, change in human behaviour and provision of sanitation infrastructure in the community, water pollution and control on water related diseases is unmanageable. There should be regular seasonal water level and water quality monitoring of groundwater sources. There is a need for wakefulness among the general public through media awareness raising programmes. Local governments and NGOs can contribute more to change the scenario; they can provide improved, contamination fee and healthy environment by controlling open drainage system. n

The authors work at the Centre for Climate Research and Development (CCRD), COMSATS Institute of Information Technology (CIIT) Islamabad.Email: toqeer.ahmed@comsats.edu.pk

Published in Dawn, Sunday Magazine, January 10th, 2016