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Comment by Spooky23 | Hacker News Reader

That’s really high. There’s either a big problem in your city, or they are making generous estimates to justify asking for more capital. 10-15% is more typical.

In my region, the street trees are usually getting sewer water. Residential service in older houses are usually clay pipes with lead solder that the tree infiltrates. It’s not a problem until the clay pops and roots clog it.

It varies a lot by region and jurisdiction. One of the cities near me made the mistake of using riveted pipe from rolled steel to save money 75 years ago, and regularly has catastrophic main breaks as the rivets aren’t as robust as a regular pipe.

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OP numbers aren’t only a city problem, IIRC [0] the numbers are close here in France. There’s a startup that try to tackle it : www.leakmited.com/en I applied there 3 month ago and they never responded. Can’t blame them but I’m a bit sad: it’s the dream impact-job.

[0] 20% apparently https://www.eaufrance.fr/repere-rendement-des-reseaux-deau-p...

I wouldn’t be too sad. There are lots of companies offering ML leak detection. Most or many are using fibre optics and using them to detect changes in temperature or noise along the line. Sample the signal for period of time and run it through a model and you have leak detection.

Good catch. I mentioned it to one my wife’s former coworkers and he laughed - I guess our city is in particularly good shape. Mea culpa.

Mexico City, by some estimates loses about 40% of its water that does enter its system, whether it's through leaky pipes or being stolen.

https://www.marketplace.org/story/2024/05/27/mexico-city-wat...

My city loses about 30% of the water going through it's pipes, including leaking wastewater directly into rainwater drains ( left untreated).

I believe some of the plumbing was wood pipes in select very busy parts of the city until somewhat recently, as it was a nightmare to replace.

> as it was a nightmare to replace.

I suspect this is the problem with all aging infrastructure; 100 years ago or more, water, sewage and electricity was deployed everywhere, but then they just kept building and rerouting and now the systems have become unmaintainable.

I wonder if this has improved in any way since then in newly constructed areas / cities. I'm thinking a service tunnel underneath roads with all the pipes and lines clearly marked and installed in a highly accessible fashion. Said service tunnel can also be used for daring heists and escapes and the like.

As others have mentioned here in Austin there are several creek beds that flow beautiful crystal, clear water during the droughts. It's because the pipes leak that much. Treated drinking water as it turns out is quite beautiful flowing down an otherwise dry creek bed.

Here in Germany, we estimate sewer infrastructure to last anywhere from 50-100 years, and water mains around 50-ish years. After that, it needs replacement or, that's the modern thing but it's a one-trick pony, re-lining.

The prudent thing would be to set aside and invest a tiny bit of money every year to fund a replacement, but unfortunately modern economic theory ("run lean") and manufactured income crises (aka, politicians going for lower taxes and utility rates) have led to a lot of infrastructure being utterly dilapidated and no savings left, and now we need to invest untold billions of euros raised from debt to keep it running.

Unfortunately, a lot of the deciders are already dead, and for those that still live, it's fallen out of favor to hold them accountable.

Smart is to have a crew that replaces a little every year. That way they build expertise in how to do it and there isn't a large expense all at once. You can likely get a discount with private plumbers because you want it done sometime and so they schedlue around other customers who want it now.

That doesn't track because the real cost to replacing underground infrastructure is not the digging, materials, or labor. We avoid such maintenance as long as possible because shutting down a road is usually very expensive in terms of second-order effects.

Digging up a pipe and replacing it is actually pretty cheap and easy. Disrupting a main thoroughfare is incredibly expensive in terms of lost productivity, transport, shipping.

there are enough roads in any city as to rebuild a few every year. Pipes don't last as long as pavement in general.

Pipes have lifetimes of 2-10x roads... where's your data from?

Roads[0]: Asphalt (18 years), Concrete (25 years) - requires good expansion gaps, good substrate, zero roadwork over its lifetime.

Pipes[1]: HPDE (50-100 years), PVC (50-70 years), Reinforced Concrete (75-100 years) Vitrified Clay Pipes (Several centuries), Galvanised Steel (40-70 years)

[0]: https://www.ayresassociates.com/the-long-and-short-of-it-lif...

[1]: https://trenchlesspedia.com/the-lifespan-of-steel-clay-plast...

A city could replace pipes preventatively as part of road resurfacing when the pipes are sufficiently old.

Not that easy. A road resurface, that can be done in a few days worth of work, less if you hire enough machines and staff.

A pipe replacement? Sewer mains at least here in Germany tend to be anywhere from 2 to 8 meters below ground. That's a lot of soil to move. Freshwater mains is below freezing depth, so usually around 1-2 meters below ground. And above that is a ton of other wiring... electricity, phone, fiber, cable tv, gas and district heat/cooling just to name a few, so when you want to replace the sewer mains, it involves a lot of companies, plus the city authorities for coordination, permits, traffic re-routing (a bus route is bad enough - a tram line or a legit full size train line is a nightmare).

Outside of immediate emergency work from a burst pipe, replacement works take years to plan.

That it takes years to plan means you have time to work with the road people. We will have to dig this road up anyway don't resurface it. Often they know roads were built sub-modern standard and want to dig it up but it isn't ecconomical.

this needs to be done for all roads constantly sometimes the pipes are still good and you resurface, sometimes they will fail in a few years so may as well dig them up since we have to do the road now.

This just sounds like a different way of saying "one more lane bro, trust me". Usually one doesn't "shut down" a road, but divert lanes, perform construction outside of peak hours (e.g. at night) etc.

Finally, some people may even consider the construction too much of a hassle and use the car less. Empirical studies suggest that "removing" a road does not cause productivity loss overall, since having the road in the first place induces a lot of "non-essential" demand.

That arguement is stupid. the world is not only about productivity. If people want to do something just because they enjoy it then they should. If the lack of a way means they do something else that is a loss. The whole point of Cities is all the options, if you want lack of options there are a lot of small towns - and even they have more options than you want to allow.

now it need not be by roads - a great transit system should enable moreeobtions. However the point is all the things you can do if you choose not a train or road to nowhere.

This whole thread reminds me of the Edinburgh tramworks; despite there having been 19th-century trams on the same street, the modern trams are heavier. So the tram building project turned into a saga of underground "technical debt": sewers had to be rebuilt to take higher weight overhead, which meant digging up everything buried in the road, all the pipes and wires, plus extra bits of archaeology. Hence massive cost overruns.

It is not cheap nor easy. For many of those pipes, especially yhe waste water ones, there are no AS-BUILDs, and they are unmapped in a very real sense.

In Los Angeles, they have basically given up on doing any preventive maintenance of the water/sewer lines. They just wait for something to break and replace it. We have areas with pipes over a 100 years old. Too expensive to dig up huge areas of the city to replace the lines all at once. This may also have something to do with the notoriously corrupt LA Dept. Of Water and power too. Other cities in LA County do periodically replace the lines, but it's still tremendously expensive.

TIL clay pipes are a thing but it does make a lot of sense there would be.

These are probably the longest lasting option we have right now, and is far more eco-friendly than the closest alternatives, plastics or concrete.

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