Pakistan, Sept. 13 -- Karachi's waste problem is usually measured in tonnes. The city generates an estimated 14,800 tonnes of municipal waste every day. But the real story begins after the first tonne leaves a household. It travels through neighbourhoods, onto roads, into trucks, through transfer points and eventually to landfill sites. At every stage, something is lost-money, recyclable material, environmental safety and, sometimes, public health. Karachi therefore does not have only a garbage problem. It has a waste-management problem.

The quantity itself is becoming difficult to ignore. Estimates have varied over the years because different studies use different definitions and methods. Research has placed Karachi's daily generation a...