Local resident Steve Palmer, who first contacted the BBC about the issue last year, said he was still concerned about plans for more homes in the area.
“You sometimes walk over the bridges that go over the river and you have to hold your breath, and that’s got gradually worse over the years.
“There are thousands of houses to be built which are going to rely on this sewage system, and if it’s over capacity now, I really can’t imagine what the result is,” he said.
Parish councillor David Wood said the area was “overloaded” with new developments.
“We just haven’t got the capacity to handle any more, and if you keep pouring developments in, the infrastructure is just not there,” he said.
Ms Cawley said the sewer improvements would accommodate “future growth”.
“I understand it’s frustrating but it takes us 12 months to do all the right surveys to make sure we understand the volumes in the sewer at all points of year,” she said.