Water authorities warn: Flushing frying fat causes sewer blockages, millions in costs

Dutch water authorities are urging residents not to pour frying fat or oil down sinks or toilets during the New Year period, citing recurring sewer blockages and expensive treatment costs.

The Union of Water Boards (UvW), which represents all 21 Dutch water authorities, reported that the problem peaks around the holiday as many people who rarely fry at home prepare oliebollen.

The UvW estimates that households generate about 10 million kilograms of frying fat and vegetable oil annually. Approximately 6 million kilograms are collected for recycling, while the rest ends up in residual waste or flushed into the sewer. “Ultimately, we all pay for the costs and problems caused by that fat,” the water authorities said.

Residents are encouraged to dispose of frying fat and oil at collection points. According to the UvW, about 60 percent of Dutch households already participate in these programs.

“After New Year’s, there is always a peak, because people who rarely or never fry now do so for oliebollen,” a UvW spokesperson said.

The regional water authorities, Waterschappen Vallei en Veluwe and Rivierenland, which manage sewage and water treatment in their areas, have noticed the increase firsthand.

A spokesperson for Rivierenland explained, “The fat is then captured in a grease trap at our treatment plants. The grease traps fill faster due to the frying fat. Our biological treatment does not break down oils and fats. This must be processed in a special facility for oils and fats. This results in extra costs. Furthermore, it can no longer be recycled.”

In Gelderland, Waterschap Rijn en IJssel reported minimal impact from New Year’s frying. “Our treatment plants can handle it,” a spokesperson said. “Perhaps people in our region behave very properly.” She added that only the three Ps—poop, pee, and (toilet) paper—should be flushed.