"We have used cameras to investigate the line and, several years ago, new sewer lines were installed in an effort to alleviate the issues."
Mr Burt said fat deposits, gravel and stormwater infiltration were often problems for old sewerage systems such as Dargaville's.
Alarms were recently installed and routine maintenance at the nearby 35-year-old pump station was carried out twice weekly.
"Apart from the health and environmental issues, the smell is horrendous," Mr Carter said. "They are large spills - several hundred litres per hour of everything that goes down the neighbourhood's loos.
"The last spill in early April was the final straw. It took more than two days and lost hours of work to have the clean-up actioned."
The clean-up wastewater ran into a small stream below the house which fed into the Awakino Stream, Mr Carter said. The spills were always reported to Northland Regional Council but not a lot had been done.
The Northland Regional Council area manager in Dargaville, Gary Treadgold, said the council would monitor the stream.