Between 1996 and 2005, naturalcatastrophic events had an estimated cost of US$575.2billion world-wide. In particular, it has been observed thatdeveloping countries are relatively more affected by suchevents, since its gross domestic product (GDP) have showedsharper declines than developed countries' ratios. OnAugust 15, 2007, an earthquake measuring 7.9 on the Richterscale shook the southern part of the central coast of Peru,with devastating consequences. Given the magnitude of thedamage caused, one wonders how much less the cost ofrehabilitating water and sanitation systems might have beenif public investment projects and management of urbanutilities (companies in charge of the water and sanitationprovision), had incorporated disaster risk reductionmeasures. For this reason, and because this is a key publicsector service for the wellbeing of population, the WorldBank's water and sanitation program commissioned ApoyoConsultoria S.A.C. to conduct a research on the water andsanitation sector in order to attend the following inquiry:how much unpreparedness cost to the sector providing waterand sanitation services? In other words, in economic terms,what will have been the gain to society or thereconstruction savings if risk prevention measures had beenincluded in the management of services in the sectorproposed for the analysis?