The National Water and Sanitation Council has revealed that the recent water contamination in some parts of Lusaka was caused by sewage overflow.
National Water and Sanitation Council Acting Director Eng. Peter Mutale said preliminary findings on the investigations of water contamination affecting parts of Lusaka by the the Council showed that there was sewage overflow that was reported from a housing block in close proximity to the boreholes.
Eng. Mutale added that the storm water from the complex which is discharged near the borehole site which might have infiltrated into the ground water system.
He said 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.
“Microbial contamination was recorded in two boreholes located on the periphery of the Napsa housing complex. these boreholes supply water to Nyumba Yanga, the Napsa Housing Complex parts of ibex hill and Malata areas,” he said.
Eng. Mutale observed that 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.
“Furthermore, sporadic cases of sewage overflows were reported around Nyumba Yanga area in the period preceding the start of the new year. These conditions as well as the aforementioned, potentially propelled diffuse water contamination,” he said.
Eng. 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,” he said.
He added, “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.”
“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.”
The NWASCO Acting Director 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.
“While accidents are bound to happen in water systems, the fact that the networks in question are a direct pump-into, which do not have reservoirs to accord chlorine sufficient contact time, the utility should have realized 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.”
Eng. Mutale has since directed that the company flushes the two boreholes and system where contamination has occurred until the source and network are safe and that during the period of flushing, alternative water supply should be provided to the customers affected.
The regulator has also directed that LWSC immediately takes charge of the operations of the borehole within the Napsa Housing Complex and install a chlorination system and that super chlorination should continue as earlier directed until NWASCO is certain that the situation is under control.
“Ensure that each satellite or production point has onsite testing equipment such as comparators, turbid and PH meters and keep records of the tests. During this period, water quality results will be reported to NWASCO weekly and not quarterly as stipulated in the water quality monitoring guidelines.”
Eng. Mutale has also revealed that NWASCO is demanding that LWSC undertakes a comprehensive review of all your chlorination systems in the city and provide a report to NWASCO by 30th January 2019.
“Take stock of all households in the affected areas and submit a list to NWASCO. All affected customers in the named areas shall not be billed for the month of January 2019.