This latter method was made possible by the extensive introduction of water metering, which was included in many concession contracts in the 1990s. The average household expenditure for water supply and sanitation in 2002 was 2.6%, ranging from 2.1% in the highest (wealthiest) quintile to 3.5% in the lowest (poorest) one.
Water metering, which was included in many concession contracts during the 1990s, enabled this latter method. In 2002, the average expenditure on water supply and sanitation for households ranged from 2.6% to 3.5%, with the highest quintile spending 2.1% and the lowest quintile spending 3.5%.