Type of tile ? Plastic? Clay? Cement?

If you have inlet and outlet the best way is to probe with a tile probe. Not easy or fast but better with a clay or cement tile. A good installer with lots of experience can do plastic as well.

At least get a general idea of where the tile goes but may miss laterals or tie ins. Can you access any google earth or FSA aerial maps from multiple years that allow you to see where possible lines are at ?

I've heard the smoke is a good idea as it comes out of the tile at joints etc to indicate location.

Electronic locators that are pushed up the tile are supposed to be good (no experience with them) but are somewhat limited to distance. So may need to go up part way dig open go upstream again etc.

I wish there was a way to use GPR (ground penetrating radar) to identify old lines or a way to send sonar into the outlet that would echo back through the entire tile system to use for locating lines tie ins etc.

The other alternative is someone that can witch the lines some can do it reliably others cannot. Basically 2 bent wires held out in front of you loosely in the hands when you pass over a underground utility the wires cross indicating where it lies.

I posted about this Magnetomatic device in this thread. (same concept as crossed wires)

https://talk.newagtalk.com/forums/thread-view.asp?tid=673445

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P1010001 (full).JPG (111KB - 171 downloads)

P1010019 (full).JPG (121KB - 149 downloads)

Magnetomatic1 (full).jpg (262KB - 140 downloads)

Magnetomatic2 (full).jpg (194KB - 152 downloads)