Hydraulic ram pumps and Sling Pumps

Key Factors for Sustainable Cost RecoveryReal cost tariffs sometimes also include:a) environmental costs (costs of protecting and conserving water source, or treatment of used waterdischarge);b) costs for ‘unaccounted for’ water (in some countries, unaccounted for water can represent up to60% of total water produced, which represented a considerable loss in revenues; this loss can berecovered in the tariff, while correcting measures are put in place);c) investment costs;d) depreciation costs.Metered graded rate applying a subsidy factor (see Annex 2 for example)Although tariff calculations are often developed on a project by project basis, tariffs formulas can alsobe determined at government level, as is the case in Colombia, which uses average costs to determinetariffs. A tariff requires information to be collected and then is determined through several steps:• calculating various costs,• defining the tariff,• setting the bill.Information required• Classification of users by social strata In Colombia, the Public Services Law (142/1994)classifies residential users, according to their socio-economic conditions, into 6 strata with thepoorest at strata 1 and richest at strata 6. Industries and institutions are classified as industrial andofficial users, respectively.• Consumption ranksI. Basic consumption satisfies the basic needs of a family, fixed at 20 m 3 per user per month;II. Complementary consumption, between 20 m 3 and 40 m 3 per user per month;III. Luxury consumption over 40 m 3.• Subsidies (Sub) and extra-charges according to consumption ranks and strata. For each stratathere is a subsidy (highest for the lowest strata). Official users receive no subsidy. Industries facean extra charge and receive no subsidies.• Calculating various costsAverage Investment Cost (AIC): is the cost of present and future investments in order to produceand distribute one cubic meter of water. It includes the initial and future investment (INI andFIN), the Total Water Produced in m 3 during 30 years (TWP) and the cost sharing of investmentsrecovered by connection (variable C).AIC($/m 3 ) = INI + FIN * (1 – C)TWPAverage Operation and Maintenance Cost (AOMC): is the operating and maintenance cost ofone cubic meter of water during the year. It takes into account the volume of water produced andthe leakage index (P=30%) for the same year.AOMC ($/m 3 ) = Total O&M costsM 3 produced * (1 – P)Long Term Average Cost (LTAC): is the operating and maintenance cost of producing one cubicmeter of water, taking into account the actual and future treatment capacity of the water supplysystem.LTAC = AIC + AOMC31