City drinking water tests high for copper

Copper levels in Benson’s water supply have tested at a level requiring action by the city to notify its citizens at multiple locations around the community.
Under the federal Clean Drinking Water Act, the city is required to test for copper and lead at <img src="/sites around the community regularly. The water samples are generally taken at curb stops, the Benson City Council was told at its meeting Monday night.
In tests run a couple months ago, the levels of copper exceeded federal standards at more than a dozen sample <img src="/sites. Lead levels were within the federal limits.
 Public Works Director Dan Gens told the council that elevated levels of copper had first been discovered eight months ago.  He explained the city had determined the cause to be a new formula base for polyphosphate that is put into the water pipes to main water quality and reduce copper and lead levels.
That new formula was too strong and ended up being corrosive, causing water pipes to slough off copper rather than hold it. This led to the elevated copper levels, he said. The city informed Hawkins, Inc., of Roseville that it needed a new formula for treating its water supply. The company handles the chemicals for the city’s water treatment facility.
The city then assumed the problem had been dealt with, Gens said. However, when the next round of testing was conducted copper levels exceeded federal standards. In looking into the problem, the city found that the formula hadn’t been changed. It has now made sure the new polyphosphate mix is being used, he told the council.