Lawrence, pick your flavor: an occasional funky taste and odor in the city’s drinking water or a water rate increase that will be 10 percent or more in some cases.

City commissioners at their Tuesday evening meeting will be asked to decide whether to raise water rates in order to address a sporadic taste and odor issue that occurs when algae levels spike in Clinton Lake.

The first phase of the project is expected to cost about $5.8 million. A potential second phase could add another $11 million or more.

“It is a lot of money to correct a problem that you don’t know how often it will happen,” said Mayor Mike Amyx. “But we are in the business of selling water, and we have to sell the best product we can.”

In the past, significant numbers of Lawrence residents have complained about the water having an earthy or musty taste and smell. The issue has arisen when Clinton Lake or the Kansas River have had high levels of algae, which emit geosmin or other algae byproducts.

But the last significant outbreak was in June 2012, said Dave Wagner, the city’s director of utilities. He said staff at the city’s two water treatment plants now monitor the water closely for signs of algae spikes. He said the city has seen some elevated levels over the last year, but treatment processes have caused it to be undetectable to most people.

City officials last year, however, spent $137,000 to hire a consultant to study more advanced ways of addressing the taste and odor issues. The report by Burns & McDonnell recommends $5.8 million in improvements to the Clinton Lake and Kaw Water Treatment plants and then suggests waiting to see whether the additional $11 million in improvements are needed.

“We’re hopeful the phase one improvements will take care of it,” said Jeanette Klamm, a management analyst for the city’s utilities department.

The $5.8 million worth of improvements, however, will require a rate increase. The size of the increase depends on the type of water user. Here’s a look at some scenarios, based on information provided by the city:

• Single-family residents who use 6,000 gallons of water a month would see their bills increase to $32.27, up from $30.31 currently. That’s an increase of 6.4 percent. For people who use 20,000 gallons per month — such as for lawn irrigation — the percentage increase is about 6.7 percent.

• Most residents of apartment complexes would see a decline in the water bill. A multifamily user of 6,000 gallons would pay $22.55 compared with $23.23 today. City officials explained the city’s rate modeling plan showed multifamily users were due for a decline because their usage of the system was not creating much peak demand for the system.

• The owner of a commercial business that uses 300,000 gallons per month would have a water bill of $1,207, up from $1,092 currently. That’s an increase of 10.5 percent.

• An industrial user of 2,500,000 gallons would have a water bill of $8,498, up from $7,872. That’s an increase of 7.9 percent.

Wagner said even if city commissioners decide not to pursue the taste and odor improvements there would be a rate increase for 2015 to help pay for other capital improvement projects for the water system. But he did not have information on how much lower the rate increase would be.

Wagner also cautioned that the department can’t guarantee that any treatment system will entirely address the taste and odor issue.

“But we’re certain that what is proposed will help us do a better job than what we do today,” he said.

In addition to the water rates, commissioners also will be asked to approve new sewer rates for 2015. The proposed sewer rate increases are closer to 4 percent, in most cases. When the water and sewer bills are combined, the city projects the average residential customer would see monthly bills rise between 4 percent to 5 percent. Multifamily users would see combined increases of 1.3 percent to 3.3 percent, commercial users 6.8 percent to 6.9 percent, and industrial users 5.7 percent.

Commissioners meet at 6:35 p.m. on Tuesday at City Hall.