Think about what you just said.
There has got to be a huge (as in HUGE) market for equipment that locates water underground. Anyone that put a device on the market that could do that would make a fortune.
Yet, you just said no such commercial device exists.
What that tells me is that the dowsing "technology" doesn't work. Because if it did, someone would have put it in a box and started selling it commercially for big-bucks.
No, I said "He did not have equipment for that." Some locators, such as this fellow, handle only certain kinds of underground lines, not all kinds. Hence, he did carry equipment for all kinds of lines.
There is modern technology for water location. Yes, it's superior to dowsing, but dowsing does work, too.