The Relevance of the Sodium Hypochlorite Solution Certeza as a Domestic Water Disinfecatant in Maputo.

Sammanfattning: The quality of piped drinking water in Maputo is generally poor and it affects many people, in particular the poor living in areas with inadequate or insufficient water distribution systems. In Mozambique, the chemical disinfectant, Certeza (containing diluted sodium hypochlorite), is used to treat domestic water at the consumers’ end. It is well known that chlorine products used for disinfection of water with high amounts of organic matter can produce disinfection by-products (DBP) that can lead to future health risks for consumers. However, it should be noted that the health risks caused by DBPs are very small compared to drinking unsafe water. Nevertheless, it is important that DBP levels are monitored and taken into account while considering disinfection measures of treating water for drinking purposes. This study serves to find out if Certeza should be used as a disinfectant for domestic water treatment in Maputo. Analyses of pH, turbidity, nitrates, nitrites, ammonia, organic matter and coliforms were carried out in five different areas, including city central, suburbs and rural areas, to obtain a representative sample of the water quality. In parallel to the analyses 75 interviews were carried out during April to May 2014 to assess whether the users believed their water was safe to drink or not. This provided the opportunity to find out if people treat water domestically and, if so, at what quantities Certeza is used. Water distributed by FIPAG had generally high levels of organic matter and also high levels of total coliforms. Ground water presented lower levels of organic matter, but variable levels of faecal coliforms. Water collected in the rural area showed to have the highest levels of organic matter and variable levels of faecal coliforms. The results from the interviews presented that 75% did not feel safe drinking the water, but still only 40 % treats their water. Out of these 40 % only 20 % used Certeza for domestic water treatment. Concluding, Certeza or any other sodium hypochlorite product is not suitable for all kind of water sources. Water with high levels of organic matter and bacteria are the problematic resources. Certeza should be used in areas where there is a risk of contaminated water, but it ought to be discussed whether it should be promoted for private domestic use, especially without informing about the possible consequences.