Non-revenue water is one of the lowest hanging fruits in order to improve the efficiency of water utilities around the world. Especially the water losses in the distribution systems are obvious when analysing data from water utilities. It is more than a decade since IWA presented the ‘best practice’ standard water balance but many water utilities have still no overview of the situation. Around the world we still see that non-revenue water accounts for 25 to 50 per cent of the total water supply and in emerging markets we have experienced even up to 75 per cent non-revenue water.

Significant reduction in non-revenue in Denmark

Danish water supplies have over the last decades worked intensively on reducing non-revenue water and managed to significantly decrease. It all started in 1989 by a tax on the water produced by the water utilities. The water supplies hereby got a strong incentive to reduce water losses and improve the quality of the distribution system. The result today is that most Danish water supplies are below 10% non-revenue water. The water utility of the capital of Copenhagen HOFOR has currently a non-revenue water of around 6.5%. However, the limit is actually much lower as many decentralised Danish water supplies have almost eliminated non-revenue water, e.g. Lynge Overdrev Water Supply which for more than a decade has had less than 1% NRW and all water consumption being metered.

The many benefits of reducing non-revenue water are obvious. The less drinking water the utility needs to treat and pump out in their network – the less energy the utility use. The less leakage from drinking water into sewage pipelines – the less sewage water needs to be pumped and treated. The less water loss – the less water abstraction – and the stress on the environment. The less leakages in the pipelines – the less risk of contaminating the drinking water.

The measures to reach this low national level have been many. Among the most important are setting up meters for all consumers, dividing the network into district metering areas, introducing pressure management to decrease pressure, installation of frequency converters for distribution pumps, establish hydraulic models of the distribution system, identify illegal connections, conducted active and not least focused leakage detection, recording of leakages and network quality on GIS, and in general optimising the investments in renewals of the most deteriorated pipelines and joints.

At the same time of reducing the non-revenue water, Danish utilities have managed through awareness campaigns and pricing without subsidies to lower the water consumption in Denmark. Nowadays, the Danish utilities have a good overview of their water distribution network, an overview of the daily production and consumption and in addition much lower energy consumption than a decade ago.

Sharing knowledge about non-revenue water

Many Danish consultancies work closely together with the Danish water utilities helping other utilities around the world decreasing their water losses. Within the last years such knowledge-sharing projects have been implemented in Malaysia, China, Thailand, Georgia, Taiwan, Turkey, Abu Dhabi, Saudi Arabia, Mali and South Africa.

Recently, the entire Danish water sector, involving consultants, equipment suppliers, contractors, universities, authorities and water utilities have prepared a knowledge-sharing platform “Rethink Water” with some white papers presenting examples of state-of-the art practice. Three of the white papers are focussed on water supply and non-revenue water: “Greater water security with groundwater”, “Ensuring great-tasting and safe tap water 24/7” and “Reducing urban water losses”.

The white papers can be downloaded free of charge at http://www.rethinkwater.dk/whitepapers.