Since Chicago Mayor Rahm Emanuel announced last month that water rates for Chicago and the surrounding 125 suburbs that buy water from the city could increase by 70 percent over the next four years, as part of a plan to revamp the Chicago’s aging sewers, suburban officials have nervously awaited official word of a cost hike.

“Our representatives from the Brookfield-North Riverside Water Commission have told us that they expect these increases to be passed on to them,” said Brookfield Village President Michael Garvey at a meeting of that village’s board of trustees on Oct. 24. “I see no choice for the board but to pass that on to the actual customers.”

Both Brookfield and North Riverside purchase their water from the Brookfield-North Riverside Water Commission. Riverside buys its water from the village of McCook.

If Emanuel’s proposal survives the city’s budget hearings, proceeds from the increased rates will be used to improve Chicago’s outdated water and sewers systems, which, according to Emanuel, are long overdue for an overhaul. 

Chicago relies on suburbs that purchase its Lake Michigan water for a considerable amount of the city’s water revenue. In 2010 alone, 47 percent of Chicago water revenue came from the suburbs, according to Tom Laporte, a spokesperson for Chicago’s Department of Water Management.

The water rate hikes have yet to be approved as part of Emanuel’s budget plan for fiscal year 2012, but suburban leaders are concerned that their constituents will be paying for projects that do not directly benefit them.

“Our increase is going to go to improve the city of Chicago’s water system, and Mayor Emanuel said publicly this is to upgrade the infrastructure that gets the water out here to us,” said Garvey. “We’re just shocked at the amount of the increase and how it’s being likely passed on to us.”

Laporte asserts that repairs to suburban feeder mains, water purification plants and the conversion of four pumping stations from steam to electric are all part of the planned renovations that will ultimately benefit both the city and suburbs

The proposed increase will raise the rate at which municipalities pay for water 70 percent by 2015, hiking the cost of 1,000 gallons of water from $2.01 to $3.82. A 25-percent increase that’s suggested for 2012 would be the largest single-year jump since 1981, and would bring the water rate to $2.51

Rises in the water rate are not uncommon. The city has raised the water rate 31 out of the last 34 years. The rate has been increasing more dramatically since 2008, though, rising 44 percent from 2008 to 2010. Even with these increases, said Laporte, Chicago’s current water rate is low when compared to similarly sized cities.

“Chicago has the lowest water rate of any medium-to-large-sized city except for Memphis, Tenn.,” Laporte said.  Memphis charges a rate of $2 per 1,000 gallons.

Sewer rates for Chicago citizens will rise as well, from 86 percent to 100 percent of the gross water bill, by 2015.

While suburban communities may disagree with footing the bill for city projects, by law, the city must charge the same water rate for all of its users, Laporte said.  And many community leaders acknowledge that little can be done when the city chooses to raise its water rates.

“The thought is, and I think it’s a realistic analysis, is that the city of Chicago controls the water source,” said Garvey. “In terms of the alternatives or going somewhere else, they know they have a monopoly. They know we have nowhere else to go for water realistically at this point.”

What the rise in the water rate means to the residential and commercial consumer varies from village to village. The majority of suburbs charge rates higher than the Chicago water rate, up to $13 per 1,000 gallons in some cases, in order to cover their own operating costs.

The average suburban water rate was $5.22 per 1,000 gallons in 2010, $3.21 over the cities’ water rate.

In 2010, for instance, according to the Illinois Department of Natural Resources’ Water Rate Survey, Brookfield charged its residential and commercial water customers $5.93 per 1,000 gallons of water.

North Riverside charged residential customers $4.05 per 1,000 gallons and commercial customers $9.13 for that same amount. Riverside already has some of the highest water rates in the area, charging residential and commercial customers $9.76 per 1,000 gallons.

“I know a lot of people are having trouble paying their water bills,” said Garvey. “This is going to make a major impact on a lot of people’s budgets.”

Bob Uphues and Nick Moroni contributed to this article.