The Honolulu Board of Water Supply today unanimously approved a 70 percent increase in water rates over the next five fiscal years.

The first in the series of five annual rate increases would add an extra $6.99 a month for a typical residential home next year.

The board’s approval means water rates will go up 9.65 percent every year for the next five years starting in January, when rates will jump from $2.79 to $3.06 for every 1,000 gallons of water.

The current average bill of $39.19 will climb $27.53 to $66.72 with the last increase in July 2015, the beginning of the city’s 2016 fiscal year.

No one from the public testified on the rate plan today but a public hearing on the proposal was held in August.

Some of the rate increase will be used to shore up Honolulu’s aging water system, acting BWS manager Dean Nakano told the board.

The BWS maintains nearly 2,100 miles of pipeline and 47 percent of the pipes are more than 40 years old, Nakano told the board.