How to keep costs down and help achieve the Millennium Development Goals for water and sanitation

摘要

Annette Bos and her colleagues make a good case in their paper 'Health benefits versus costs of water supply and sanitation' (Water21, October 2005), but I wonder if it's not just a bit too complicated and whether therefore it can really help in the achievement of the Millennium Development Goals for water and sanitation. Why too complicated? Mainly because of their use of disability-adjusted life years (DALYs). DALYs are not an easy concept, and even those who claim to understand them can be quite surprised by what can happen when they're used - a good example of this is the tolerable additional burden of disease used in the 2004 WHO drinking water guidelines of 1 x 10~(-6) DALY loss per person per year; this is the disease 'cost' of drinking fully treated drinking water, but what does 1 x 10~(-6) DALY loss per person per year actually mean? Well, a year has 60 x 60 x 24 x 365 seconds, so 1 'micro-DALY' loss per person per year is a loss of around 32 disability-adjusted life seconds per person per year. So if we all drink WHO quality drinking water, then we'll all be 'ill' for around 32 seconds a year!