HARARE City Council has a sewage collection efficiency of 71 percent, meaning that almost a third of waste water ends up spilling into the living environment.
Around 60 percent of the estimated 330 megalitres of sewage collected from communities every day is lost before it gets to a treatment plant.
“All our treatment plants have a design capacity of 219.5 megalitres per day, but we only have 38 megalitres per day,” said Simon Muserere, the Harare City Council waste water manager.
“This whole vicious cycle has to be broken somewhere, somehow.”
He said the council was targeting to increase collection capacity to 80 percent as the bulk of the uncollected sewage was within the southern incorporated areas which could not be connected to the sewer system at the moment.
Muserere said the trunk sewer from Kuwadzana to Crowborough was broken and discharged straight into Little Marimba River as well as the stream crossings at Glen Norah.
“We checked the hydraulic retention time of Lake Chivero, and it is 100 to 200 days which comes up to three to six months.
“What this means is that if we have rains today, after six months, all the rains would have been flushed out of Lake Chivero and this raw sewage would have filled it,” he said.
“It also means treatment of water becomes complex. We have a high cost of water treatment chemicals, frequent back washes and we will lose another 30 percent of water through backwashing and other losses at the treatment plant.
“We should not only respect the clear water, but also the polluted water from the sewage treatment plants, the trunk sewers and also the bioreactor system in the treatment works that protects the city from all these contaminants.”