dear Rajesh:
I am dividing your questions in three:
-Is there not a better way to decrease the cost of access to a sufficient amount of drinking water using a different approach than a gravity flow system from a spring?
- Is it not preferable, given a fixed amount of available money, to provide a small amount of safe water to a lot of p...
dear Rajesh:
I am dividing your questions in three:
-Is there not a better way to decrease the cost of access to a sufficient amount of drinking water using a different approach than a gravity flow system from a spring?
- Is it not preferable, given a fixed amount of available money, to provide a small amount of safe water to a lot of people rather than a larger amount at a higher cost?
-Should we bother with very dispersed populations except perhaps by providing them with minimal drinking water from individual house filters?
Taking the fist question first:
If you look at the detail of our budgets (broken down by parts of the project) you will notice that a very large part of the cost is that of the distribution network from the tank to the individual taps. That fraction of the cost varies with the geography of the community and of its spring. But it reflects the very dispersed nature of Nicaraguan villages. For San Isidro for instance we have 1331 m of conduction line but 8992 m of distribution network, and distribution networks need to have a greater overall flow capacity than conduction lines because they have to accommodate peak demand. So the distance from the spring to the village is not the main issue and using (torrents in ravines) would only complicate the design and construction by requiring expensive pre-filters, settling channels and filters that springs usually do not need and that require more complex maintenance. Gravity flow from a good spring IS the option of choice in this case.
For the second question:
On the issue of a small quantity of water for the many vs. a larger quantity for fewer:
Many public health field studies have found that the quantity of water provided is at least as important as its quality. Concretely the amount of water needed for personal hygiene makes the difference between drinking & cooking water and aliments which are contaminated or not. So there is a minimum need below which the health issue is really not dealt with. That minimum is not reached with house filters.
Note however that the two options are not necessarily mutually exclusive: it makes good sense to equip those outlying houses that a water network cannot reach, with individual water filters of which there are a great variety and which cost little. That is assuredly better than nothing. But the impact on health of that sort of water access is very limited.
Finally, should we bother about scattered populations?
Once it is understood that there are many ways of bringing healthy water to rural populations but that each method: (RWH, hand dug wells with manual pumps, drilled wells with mechanical-electrical pumps, gravity-flow systems from springs or from streams , filtering of contaminated water by several different techniques, even desalination, and some others) comes with very different advantages and disadvantages including of course cost, so that the choice between several of them is not clear-cut, (apples and oranges), there remains the fundamental question :
Because money access is limited, do we only go after the most cost-effective populations and leave the others without decent water? Years ago in the region of Matagalpa APLV picked up some really difficult and relatively expensive projects (that had been turned down by all other available water agencies) –precisely because the villages involved had nobody else to turn to. This tends to be our attitude to this day.
Breslin has already dealt adequately with that issue. But in the end the question is: Do we want to qualify the statement that adequate drinking water is a right for all? That seems to be a good subject for debate.
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