 of assigning economic and marginal costs and is a highly contested concept. Typical agreed ELL are of the order of more than 20%. A further problem is leakage from customer supply pipes. Only where there is universal metering does the customer have an incentive to reduce the leakage. In England the water companies have consequently offered to take control of customer supply pipes (and also sewers), in order to ensure that these are better maintained. Losses from distribution systems are a global problem, but the situation in the developing world is especially acute, with too many people without access to safe and affordable water supplies and sanitation. For a variety of reasons water systems have been unable to keep up with the rapid urbanisation of developing countries. While in the 1980s more people in urban areas gained access to safe drinking water - many countries doubling the provision of new water services - more recently the population has begun to outpace the gains made. In Jakarta the water supply and disposal system was designed for half a million people; in 2000 the city population was more than 15 million (Cosgrove and Rijsberman, 2000). It has been estimated that in 1980 there were some eight cities in the world with populations over 8 million people; by 2015 there will be 36, of which 23 will be in Asia (Brinkhoff, 2004). To add to these difficulties in many major cities in the developing world, piped water supplies are intermittent and do not meet accepted quality guidelines (World Development Report, 2004). As water for industrial use has become both scarcer and relatively more costly, usage has declined. In Japan industrial water use has dropped by some 25% since the 1970s in spite of increasing industrial output. In the United States there have been similar trends, due in part to improvements in manufacturing technology but also to the changing economic structure of industry. In parts of England (East) and in Sydney, Australia, increases in domestic demand have been met from the serendipitous