The way it sits along Lake Michigan, you’d think Chicago would have a few problems bigger than water. But getting that water to homes and businesses takes a massive underground network - one that’s crumbling, according to Mayor Rahm Emanuel.

To speed up replacement of old water and sewer lines, he’s asking for a huge increase in water fees. As part of our coverage this week of Emanuel’s budget, we looked closer at the water proposal, and how the mayor is selling it.

There are tens of millions of dollars of tax, fine and fee increases in Emanuel’s proposed budget. None are likely to affect the average Chicagoan as much as the water fee hike, beginning with a 25 percent boost next year.

“The extra cost will equal about five cups of coffee at Dunkin’ Donuts a month,” Emanuel said during his budget address to the City Council on Oct. 12.

“I don’t drink coffee, so I’m still trying to do the math,” said Ald. Joe Moore of the North Side’s 49th Ward.

Well, Moore can put down his calculator. The administration claims the water and sewer fee increase adds up to - on average - $120 per year. Although, the cups of coffee keep multiplying after that.

By 2015, Chicago households - and suburban ones who also get their water from the city - would pay more than double what they do now. Also, many nonprofits and churches that currently get a pass on water bills would gradually have to start paying.

All that would help finance a $4 billion dollar-plus plan that is expected to nearly triple the current speed of infrastructure replacement.

“We have about a thousand miles of water pipe that are 100 years old or older,” Emanuel said. “Despite our budget problems, we cannot delay their replacement any longer.”

Plus, Emanuel announced, the work will mean 1,800 jobs a year over the next decade, not an insignificant selling point at a time of high unemployment.

Two days later, the mayor scheduled a press conference to make the pitch again. And, one day after that…

“The pipe broke at 8:30 Saturday morning,” explained Tom Powers, Emanuel’s water commissioner, at a press conference at 47th and Loomis. That’s where a more than 80-year-old 24-inch water main broke. “We lost about 1.7 million gallons of water through this break alone.”

The timing was perfect: a ready-made TV event, flooded neighborhood and all, to demonstrate the need for the water fee increase. There have been about 250 water main breaks this year in Chicago, but this one got a lot of attention, no doubt because the city called attention to it.

“Coincidental, or foresight on the mayor’s part?” said Ald. Willie Cochran, when asked about the timing.

Part of Cochran’s 20th Ward was affected by the water main break. I asked him if the neighborhood flooding makes the increase an easier sell to his ward’s residents.

“It’s not an easy pill to swallow when you start talking about increasing fees at this time, as it …was in the past,” Cochran said. “It wasn’t done in the past.”

Actually, it was done in the past. From 2007 to 2010, water rates jumped about 50 percent. Emanuel’s proposal would raise combined water and sewer rates more than 100 percent more over the next four years. Hikes after that would be pegged to inflation, every year.

If residents sign up for a free city-installed water meter, the mayor claims, the increases can be blunted. Though Emanuel is quick to point out that Chicago residents “currently pay the lowest price for water of any big city in America.”

In fact, Memphis has lower water rates. (Emanuel just doesn’t count Memphis as a big city.) But the point is the same: Chicago’s water is cheap.

“For years - decades, the water sold by the city of Chicago has been under-priced,” said Josh Ellis, a water expert with the Metropolitan Planning Council.

Ellis said the fee increase would make Chicago residents value their water more, leading to more conservation. Ellis supports it, with a hitch.

“I would like to see the city of Chicago create some sort of reporting system, whether it’s on the bills or on the website or wherever, that says, ‘Here’s how many miles of pipe we replaced in January, here’s how many we replaced in February, here’s how many we replaced in March.’ So that we know how much is getting fixed, and we know that there’s been a benefit,” Ellis said.

Even if the city doesn’t put that information on water bills, Ellis notes Chicagoans would see the work happening, torn-up street after torn-up street.

“If we’re going to replace 900 miles of century-old water pipes, they’re definitely going to notice all of the repair projects,” Ellis said. “Will they have a fundamentally different experience when they turn on the tap to get a drink of water or take a bath or something, no. I mean the water’s going to look the same, it’s going to taste the same, it’s going to be the same water.”

But it would be delivered with more reliability, less waste, and - at least relative to today - a much higher price tag.