A university professor says a proposal by Regina's mayor to add orthophosphate to the Regina water supply to prevent lead from entering drinking water it is not worth it when only five per cent of the population are affected.

Orthophosphate is used as a lead control measure in New York City, Washington D.C and Flint, Michigan. The chemical can prevent lead from entering into the water by forming a protective layer on the inner walls of the pipes.

Regina Mayor Michael Fougere gave a notice of motion on Dec. 3 to fast-track replacing the remaining 3,600 lead pipes in the city by 2025 and also to add orthophosphate to the city's water supply.

"At this moment, it could be a solution," Jinkai Xue said. "It's a temporary solution but it cannot be a permanent one — it's a better idea if it were to completely replace those problematic pipes."

Xue is an assistant professor in the Faculty of Engineering at the University of Regina who specializes in drinking and wastewater treatment.

Four main risks to orthophosphate in the water

There are risks when it comes to orthophosphate, Xue said.

"For instance, it's not a very robust solution," Xue said.

First, if the pH of the water changes, the phosphate may become less effective. Second, if pipes are serviced, lead can still get into the water, Xue said.

Third, bacteria and algae use phosphates as nutrients. Adding a phosphate to the water may cause more bacteria to grow within the pipe, he said. And lastly, if there is a leak in the water system, the phosphate could get into the groundwater, he said.

"I would recommend we use our phosphate only if it's possible if we can apply only to those lead affected areas," Xue said.

City Workers replace a lead pipe in the Cathedral neighbourhood of Regina in November, 2019. (Heidi Atter/CBC)

The notice of motion proposed by the Regina mayor proposes to add it into the entire water supply.

Xue said filters for the five per cent would be a better solution than adding it into the entire water supply. Further holistic research is needed to make a more informed decision on whether or not to add it into the city's water, he said.