This paper reports about a forecast of drinking water consumption in Hamburg
up to the year 2045 which was done in co-operation of the Institute for
Social-Ecological Research with the Ifo Institute. While the Institute for Social-
Ecological Research was responsible for the drinking water demand of
private households, the Ifo Institute undertook a long-term forecast of the
industrial and commercial drinking water consumption. Comparable water
demand forecasts for other cities or regions treat the industrial water consumption
compared to domestic consumption rather rudimentary. The innovation
of this forecast versus previous, conventional approaches is the choice
of the workforce instead of the population as a reference point for the water
requirements of enterprises. It is described in this paper how the problems of
predicting industrial and commercial water consumption based on limited
information were solved. Forecasts of sectoral employment were completed by
determining the specific water needs for each sector and by assumptions
about efficiency improvements in drinking water consumption. Those assumptions
were secured through written and oral inquiries of major customers
of the Hamburg Waterworks and experts from the water sector.