Winnipeg city crews will start cleaning water mains this weekend as part of an effort to clear up the discoloured tap water that has started flowing from people's taps again.

The water main cleaning program will run every day until the late fall and will target 646 kilometres of pipe, about a quarter of the total number of water mains in the city.

Officials said the main cleaning would have been underway by June, but the start date was delayed while crews were dealing with frozen water pipes.

The city says it plans to clean all 2,585 kilometres of water main over two years, instead of the usual six years, in the hopes of reducing the amount of discoloured tap water.

Officials say they hope to finish cleaning all the city's water mains by the fall of 2016, weather permitting.

Residents can check if and when their block will undergo water main cleaning on the city's website.

Crews will deliver information packages to residents whose streets will undergo water main cleaning up to a week in advance, according to the city.

Number of reports up this year

The city says it has received 1,284 reports about brown water between January and June — up from 1,018 reported during the same period last year.

A city spokesperson said the higher number is due in large part to a high number of water main breaks this past winter.

There were 1.5 times more water main breaks in the first four months of this year than there were last year, according to the city.

There were 538 brown water reports between April and June of this year, compared to 754 during the same period in 2013.

Manganese identified as culprit

Many residents reported having brown water last year, prompting the city to hire engineering consultants to find a possible cause.

The consultants' report, released in January, identified excess levels of manganese as the "primary contributor of discoloured tap water," according to the city.

The report also said a chemical that was used to treat the water supply, may have exacerbated the problem because it contained a higher concentration of manganese.

When the report was released, city officials promised to ramp up the water main cleaning schedule to get rid of the manganese buildup.

The city has since switched to a new water treatment product that contains less manganese and cleaned three in-town water supply reservoirs to remove any built-up manganese sediment.

Geoff Patton, the city's manager of engineering services, says staff are making progress on the report's recommendations and hope to lower the number of brown water-related calls.

"Since the implementation of the changes, we've seen some reduction in those calls. So we anticipate, as we bring each of these changes online, there'll be benefits," he said.