So it needs to go up and down with every single contour of the land instead of being level or sloping down (say sewage) at a steady gradient?
Look I'm no builder and I understand that in an industrial context it's not so simple.
But residential areas and especially where it's perfectly flat or at least level from one property to another which is mostly the case surely a standard can be applied to take the guess work out of it.
Newer areas like my own these things are a perfect grid. Find my water meter and the main line pipe runs exactly square to the road and I bet that will be the case for every single house down the street at exactly the same depth.
It can't be too hard to work with that, so the people hitting pipes must be incompetent.
(That being said they've trenched fibre here in other areas of the neighbourhood and I haven't seen any pipe struck)
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Also electricity detectors are a thing....surely the same exists for water? Or failing that detecting the pipe itself. And that might cost money but surely knowing exactly where a pipe is and avoiding the drama by hitting it will be cheaper in the long run?