Fig. 1. (Left) Three complementary approaches for improving the productivity of higher-quality water. The water level
in each glass shows how much water is used in producing a fixed value of goods and services. Substitution uses lowerquality water in place of higher-quality water for some activities. Regeneration transforms lower-quality water into
higher-quality water by treatment. Reduction achieves the same value of goods and services using less higher-quality
water. In these hypothetical examples, each option cuts by half the use of higher-quality water and therefore doubles its
productivity. (Right) Percent increase in water productivity associated with the 21 case studies described in the text (51).
These productivity improvements are illustrative only and will vary substantially in practice. The scale at which a
particular water-saving intervention was implemented is indicated. The bars are color-coded to match the three general
approaches for improving water productivity.