As early as Monday, the Board of Water Supply could decide to raise water rates by 70 percent over the next five years.

The agency has about $345 million of capital improvement projects in its queue, including replacing miles of pipeline and pumps. With the rate increase, the agency hopes to take in an additional $203 million over five years.

"I think most people understand that repairs are necessary," Board of Water Supply spokesman Kurt Tsue said. "But a lot of the questions are about what people are going to get for this increase."

Since making the announcement last month, the water agency has been canvassing Oahu neighborhood boards.

"A lot of us were taken aback because of the steepness of the increase," said Hanalei Aipoalani, vice chairman of the Nanakuli Neighborhood Board, who said he’s been waiting for the public hearing for the issue to be vetted.

The agency wants to increase water rates by 9.65 percent each year for the next five fiscal years, for a total increase of 70 percent.

This January, the rate would go from $2.79 for every 1,000 gallons of water used to $3.06. The average single-family-home customer would see an additional $6.99 on their bimonthly water bill during the first year of the proposed increase.

A typical household’s monthly water expense of $39.19 would climb by $27.43, to $66.62, on July 1, 2015, the beginning of the 2016 fiscal year.

"We see the water main breaks every day, so we do need some revenue," said Greg Knudsen, chairman of the Hawaii Kai Neighborhood Board. "But we kind of wonder why everything has to hit at once. Why are our electric rates going up? Our sewer rates, and now our water? And there is some wondering why some of this maintenance wasn’t done on an ongoing basis."

The City Council also has raised some concerns, despite having no oversight over the agency’s finances. City Councilman Stanley Chang held an informational briefing on Aug. 3 with the Board of Water Supply.

"I think there’s an awareness of the need for fiscal responsibility and cost-cutting and additional sources of revenue separate from simple rate increases," Chang said at the briefing.

Former U.S. Rep. Charles Djou, a former City Councilman who is running again for Congress, also penned a scathing letter about the Board of Water Supply, calling it "out of control."

Tsue said many of Djou’s concerns, including bonuses for executives, have been addressed.

The city auditor examined the water agency in 2004 and made 272 audit recommendations. A report issued in May said the agency has completed 146 of those recommendations.

Since 2005, no bonuses have been awarded. And prior, fruitless efforts to expand into business development activities have been abandoned, the report states.

Acting agency Manager Dean Nakano told the City Council that cross-training workers for various skills has reduced operational costs by about $1.1 million a year.

"We’ve been able to reduce the size of our crews, our overtime costs have gone down, and our response times have improved," he said, adding that the agency did not need to hire about 30 additional workers because their existing workforce was trained for various types of work.

Nakano said another rate increase is possible by the end of the proposed five-year plan. The agency would conduct an assessment by the third or fourth year.

Tsue said the agency has received "a couple of letters" of written testimony regarding the rate increase.

During Monday’s hearing, each resident will have about three minutes to testify about the increase. After it is all heard, the agency’s board of directors will either decide on the increase then, or defer it to a later date.