[schiffern]

  >Since street trees can’t get much of this from rainwater, which falls on concrete and drains into the city’s sewers, Poirier says the most likely explanation is ...

  I feel like this is burying the lede. What can be done to reduce leakage?

Seems like a better question is, why didn't we design our urban and suburban hydrology to water those trees, instead of shunting rain to an already overburdened storm system?

This is hardly a pipe dream. Village Homes demonstrated the concept[0] over five decades ago.

[0] https://www.youtube.com/watch?v=zZ7RmsJOlgc&t=980s

[Manfred]

Because it’s cheaper not to do it.

[schiffern]

Sewer systems are bankrupting municipalities worldwide. Either the city fails to grow (and can't afford to fix the pipes), or the city grows (and can't afford to shut down traffic to fix the pipes).

Far from being unaffordable, fixing our broken urban water management is the only affordable option.

[kulahan]

I see this response a lot, as if it's insightful or useful, but it really isn't. There are good times to save money and bad times to save money, and it's almost never the sole point of consideration. There are lots and lots of things we could spend more money on. Is that the goal?

[Manfred]

Any cost to a city that doesn’t have immediate utility to the people governing the city has to fight an uphill battle against everything else. And a in a lot of cases all available money is already allocated. In such an environment people generally don’t choose to make long term investments. Cheaper is easier to sell politically. And if large projects like a subway get greenlit it’s usually for an unrealistically low budget and the project ends up costing 2 or 3 times more because it’s easier to raise taxes based on sunk cost than careful planning.

[kulahan]

Thanks - that's a hell of a lot better than the original comment. I disagree, though. Officials are elected based on projects they want to undertake. Nobody is saying "I'm beating the national average cost of building a bridge by 17%!!" in their campaigns, they're saying they're gonna build a bridge. And it'll be damn impressive. A legacy, even. Might put my own name on it.

[cowsandmilk]

Citation needed. Curbs are expensive. Sewer pipes are expensive (for the last 60 years, Montreal has separated rainwater and wastewater sewers in all new construction).

Montreal likely doesn’t do it because it would lower the density of buildings.