NATIONAL Water Supply and Sanitation Council acting director Engineer Peter Mutale has disclosed that microbial contamination was recorded in two boreholes located on the periphery of the Napsa Housing Complex.
In a statement on the preliminary findings on the investigations of water contamination affecting parts of Lusaka, Mutale said these boreholes supply water to Nyumba Yanga, the Napsa Housing Complex, parts of Ibex Hill and Malata areas.
He said from the investigations, contamination was suspected to have been caused by sewage overflow that was reported from a housing block in close proximity to the boreholes and also the storm water from the complex which is discharged near the borehole site which might have infiltrated into the ground water system.
“The sewage overflow is believed to have occurred between 29th and 31st December 2018 and was inadvertently allowed to flow in the direction of the boreholes. The situation could have been worsened by heavy down pour, storm water runoff experienced in the period and leachates from the city’s poor solid waste management that then result into diffuse pollution in the aquifers,” Mutale said.
He said furthermore, sporadic cases of sewage overflows were reported around Nyumba Yanga area in the period preceding the start of the new year.
Mutale said despite the chlorination taking place at the two boreholes in question, chlorine residual was generally low and below the minimum requirement stipulated in the national drinking water standards during the initial two days of the investigation, in most areas sampled.
“At such high levels of contamination as revealed by the water quality tests, normal levels of chlorine dosing could not effectively deal with the bacteria for source or post contamination that may occur in the network. A borehole located inside the Napsa housing complex in Nyumba Yanga and managed by estate managers had no chlorination system fitted on it while two boreholes located on the periphery of the complex belonging to Lusaka Water and Sewerage Company had chlorination systems which were functioning properly,” he said.
“However, operators reported that occasional blockages are encountered on the chlorination systems in the process of operation. Though blockages were not observed on the two boreholes in question in Nyumba Yanga, this was the case in two of three boreholes inspected in Bauleni compound. Such incidences demand regular monitoring of the process and speedy redress.“
Mutale said the unchlorinated water could have tended to dilute and reduce the efficacy of the chlorine, particularly in the Napsa housing complex, where networks were suspected to be interconnected.
He said the interconnectedness though, could not be conclusively verified as network maps were not availed by the estate managers.
Mutale said the initial response from Lusaka Water and Sewerage Company was less proactive and lacked a clear strategy of addressing the issue but later improved.
He said while accidents were bound to happen in water systems, the fact that the networks in question were a direct pump-into, which did not have reservoirs to accord chlorine sufficient contact time, the utility should have realised water would inevitably reach some customers with contamination.
“In the wake of uncertainty about the cause and source of contamination, the utility should have immediately intensified surveillance and shut or flushed the network while investigations continued. During the entire course of the investigations, NWASCO has corroborated and shared data with stakeholders such as the Water Resources Management Authority (WARMA) and the Ministry of Health. The Lusaka Water and Sewerage Company has also been regularly informed and advised on the course of corrective action to be taken,” he said.
Mutale directed LWSC to flush the two boreholes and system where contamination has occurred until the source and network were safe.
He said during the period of flushing, alternative water supply should be provided to the customers affected.
Mutale said LWSC should immediately take charge of the operations of the borehole within the Napsa housing complex and install a chlorination system.
He said super chlorination should continue as earlier directed until NWASCO is certain that the situation is under control.
“During this period, water quality results will be reported to NWASCO weekly and not quarterly as stipulated in the water quality monitoring guidelines, to undertake a comprehensive review of all your chlorination systems in the city and provide a report to NWASCO by 30th January 2019…” Mutale said.
He said during the period, all sewer blockages should be attended to immediately when they occur and not within 24 hours as stipulated in the service level guarantees.
Mutale said to this effect, all sewer blockages shall be reported immediately to NWASCO by the customers as they are being reported to the commercial utility.