Salman - You need to be careful about statistics given in reports. I have worked on water and sanitation issues in Pakistan for over 30 years. The percentage of people with access to a toilet is much higher than 50%. - probably in excess of 90% in both rural and urban areas in northern Punjab for instance. The challenges around sanitation relate to wastewater disposal (very little) and operation and maintenance. Cities like Lahore are largely sewered (albeit informally in many peripheral areas). People without access to sewerage normally connect their toilets to the nearest drain, often but not always via a crude interceptor tank. There is virtually no wastewater treatment. The issue with both formal and informal sewage disposal systems is maintenance and that brings us to the main challenge in Pakistan, as far as municipal infrastructure is concerned. I agree strongly with Jeffrey's basic point, that economists and international aid agencies in general, are often concerned about peripheral issues and don't tackle some of the clearly important issues. I agree with other respondents that cost benefit analysis is not always easy but does not take rocket science to see that a water supply system or sewer that is not maintained or to which no-one is connected will not cover its costs. I would recommend that anyone who is interested in development in Pakistan should read the book 'So Much Aid: So Little Developmentby Samia Altaf. One point to come out of that book is the need to be realistic and honest about what our initiatives achieve - development planners need to get beyond the meetings with top government officials and explore reality on the ground, which is almost always very different - more difficult and more complicated - than we assume.