Contractors in Gisborne are trying to shift a half-tonne "fatberg" from the sewer network.
The district council's wastewater operations engineer Phillip Dodds said the Kaiti sewer network overloaded after rain on Tuesday, causing an unexpected overflow.
A camera was put down the pipes and found a 15m-long, 500kg lump of fat, rags, wet wipes and condoms.
Contractors are trying to cut it out using a mixture of brute force and high pressure water jetting.
Dodds said the rags and wipes should have gone into the rubbish bin, not the toilet.
He urged people to only flush the three Ps - pee, poo and toilet paper.
High evening sewer flows around 4pm put an end to the work for the day.
RNZ
