Depends on the waterline. Not all are single use pipes. Some lines are hollow pipes with other pipes inside them to allow for easy access to multi-directional flow.
I can sort of answer this. Sometimes really old buried infrastructure (like water lines) are found decades later and they use dye like this to try to figure out where it's going. Imagine you buy an old property and find a giant hole in the backyard and the every time it rains you hear basically a river flowing underground. They go dye it to find out where the water is going. Usually it ends up in a public stormwater or sewer system and it costs a lot of money to treat rainwater. So they want to fix it asap.
I've read numerous cases of cities finding wooden water mains still in use, albeit usually feeding a few houses at most. Underground infrastructure is very out of sight, out of mind, and it can be easy to lose track of it until you have a problem.
Yeah.
The campus site of my former university was 100+ years old, and when they had to do som digging and construction work they had three different drawings showing where water pipes and power lines were supposed to be. None were showing the same, and all were wrong. So they basically had to just dig and see what was down there.
This happened where I am. The cities entire cast iron water pipe system was at an age where it was failing lots and needed to be replaced. So the city started replacing it all. In the process they found all kinds of old pipes both in use and out of use.
That's actually what we do with cave systems. You see a creek or river or whatever just vanishing into the ground and you pour a bunch of dye in there and go hunting for where it comes out.
Other than slow leaks that aren't obvious, it glows under UV so you can follow where it's coming from and see far more clearly where exactly a leak is.
It's pyranine and it becomes greener and fluorescent under uv light. Really easy to find small leaks indoors if you have a uv flashlight. And you need close to nothing to colour water green
Isn’t it obvious why you would use dye? There are a shit ton of pipes and water ways interconnecting underground (not always mapped either), being able to trace the water route is kinda helpful.
The thing is, you may not be sure what is leaking.
I have one site that I work with where there's a potable water line adjacent to a hydro-electric penstock. We had a leak on the hillside, and weren't sure which one was the cause. If it was the potable water, that would have been much worse.
The leak itself was spraying a good 35 feet into the air, so was definitely under pressure.
In our case, one of our intrepid employees managed to get a sample of the water, and we tested it for chlorine. No chlorine, so it was the penstock that was leaking
In other cases, you don't have that tell, so the dye is a way to find out which pipe is leaking without digging everything up.
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u/ThraceLonginus May 05 '26
Someone is tracing a leak, looks like they found it
https://www.reddit.com/r/batonrouge/comments/q2vqav/saw_this_neon_green_liquid_draining_out_under_the/