Refer to Chapter 4 and the discussion of ceramic water filters in Benin (see Tables 4.4 to 4.6). Develop two different benefit cost analyses for a household as follows:

Question

a) Construct a life cycle cost table comparing the ceramic water filter to purchased PurTM filtered water. What is the total life cycle cost of each option, and what is the return on investment ratio for the ceramic filter?
b) What is the benefit cost of each system expressed as the cost per % reduction in coliform bacteria load?

What will be an ideal response?

Answer 1

Assumptions (as given in Box 4.2):

? The lifespan of the ceramic water filter is 2 years, therefore the life cycle period is 2 years.

? The cost of purchasing PurTM water is $0.10 per liter.

? A typical household consumes 20 liters of water per day (5 liters per person, 4 persons in the household).



a) Note that the life cycle cost for this technology is analogous to the life cycle cost technique presented in Example 12.1; just substitute the cost of water consumption for energy consumption.



Step 1: Calculate the total water consumed during the life cycle period





Step 2: Construct the life cycle cost table





Step 3: Calculate the ROI





Every $1 invested in the ceramic filter generates $46 in water cost savings as a return on investment.



b) Using data from table 4.5, and assuming that well water is an untreated water source, we see that both the ceramic filter and the PurTM system result in a 100% reduction in total coliform bacteria.



Step 1: Calculate the cost per liter of water for each system





Step 2: Calculate the cost for each 1% reduction in coliform bacteria load