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Abstract:
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A study was conducted in Blantyre, Chiradzulu and Mulanje districts in Malawi to
determine the biological, chemical and physical drinking water quality from shallow
wells. An in-situ membrane filtration test kit (Paqualab 50) was used to determine the
microbiological quality of water and a photometer was used for the chemical analyses.
Water samples were collected from twenty one covered/protected and five
open/unprotected shallow wells at four different times in a year to determine the
change in quality with different seasons. The results of microbiological analysis show
that the drinking water quality is very poor, i.e. grossly polluted with faecal matter.
Total coliform (TC) and faecal coliform (FC) values in the wet season were much higher than those in the dry season. In terms of total coliform, the results show that:
(c) approximately 80% of the shallow wells tested in the dry season;
(d) 100% of the wells in the wet season did not meet the drinking water temporary guidelines, set by the Ministry of Water Development (MoWD), of a maximum of 50 TC/100ml for untreated water.
(e) Approximately 50% of the wells failed to meet the faecal coliform drinking water guideline of 50 FC/100ml in the dry season while this figure had increased to 94% of the wells failing to meet the standard in the wet season.
(e) Covered wells were not as grossly contaminated as open wells but all of the wells tested failed the MoWD standards in at least one sample.
Chemical analyses results were within the drinking water guideline and variations during seasons were insignificant. pH values were within the guidelines in the dry season except for Mulanje district where on average 45% of the wells had pH values below the lower limit of 6.0. In the wet season 50% of the samples had pH values below 6.0.
Turbidity values were within the guideline for all covered wells in the dry season,
while about 22% had turbidity values greater than the guideline of 25 NTU in the wet
season. From these results it is very clear to see that the drinking water from the
shallow wells tested, in southern districts of Malawi, is grossly contaminated
microbiologically, with this contamination becoming worse in the wet season. |