Peso water bills are from (in Spanish) Asociación de Entes
Reguladores de Agua Potable y Saneamiento de las Américas (ADERASA): Las tarifas de agua potable y alcantarillado en América Latina, p. 66; historic exchange rates to calculate US dollar tariff equivalents are from www.oanda.org
Calculated based on OSE tariffs assuming the smallest connection (11mm, 0.43 in) and a unit tariff of 13.07 peso/m3, which applies for consumption below 20 m3/month (700 cu ft/month), according to (in Spanish) URSEA: OSE 2004 tariffs