The Covid-19 alert level change has seen Gisborne's sewerage system come under intense pressure.
Since Wednesday, there has been a 600 percent increase in blocked pipes across the local system.
Senior wastewater operations engineer Phillip Dodds said the blockages had been caused by people flushing wet wipes down the toilet.
"We seen this in the last lockdown. Wet wipes caused an 2400 percent increase and we very nearly couldn't handle it," Dodds said.
"Our system can only handle the three Ps - poos, pees and paper.
"When wet wipes get into the system they sit there and block up the pipes, which causes overflows."
Despite packaging saying wet wipes were flushable, Dodds said they were not.
He said residents needed to be aware and were reminded to not flush them.
"If we get in the position we were in the last lockdown, we will have to look at opening the pipes into the rivers, that is how serious this is.
"Our system just can not handle it and then we have a case of raw sewage in a pandemic, which is a massive health and environmental risk."
Earlier in the week, fat and rags almost completely blocked a Gisborne sewer and in July, a "fatberg" outside a Mobil petrol station on Wainui Rd caused traffic problems.