top

​Increased sewage overflows linked to wipes and other non flushables


7 March 2019

There’s been a big increase in the number of sewage overflows during dry weather.

The majority of these are caused by blocked pipes, an all too common outcome of people treating their toilets and sinks as waste disposal units.

Water New Zealand has just published its latest performance comparison report, the National Performance Review (NPR), which looks at the state of our drinking, storm and wastewater assets.

The NPR found that since 2015-16 the number of sewage overflows occurring during dry weather blockages increased five-fold.

“This clearly suggests that messages about binning wet wipes and other non-flushable items are not getting through to enough people, ” says the report’s author, Water New Zealand Principal Data Scientist, Lesley Smith.

“Wastewater operators commonly find not only wet wipes, but also paper napkins, feminine hygiene products and kitty litter clogging up our networks.

“This is having a huge impact on the wastewater network, which has only been designed to accept our pee, poo and toilet paper. The outcome of this behaviour is that sewers block up, causing sewage to overflow into rivers and the ocean. Not only does this create and expensive clean up, but it damages our environment and public health can be put at risk as well.”

She says that the number of overflows caused by pipe blockages increased from 0.4 per 1000 properties in 2015/16 to nearly two per 1000 households this past year.

“Last year there were 1,642 dry weather overflows caused by blockages compared with only 177 due to mechanical issues.

“Many people are simply not aware of the huge problems that putting wipes and other non-flushable products into sinks and toilets can cause our environment and sewers.”