Yes—PVC can be located, but an ordinary metal detector will not detect the pipe itself.

For a **100 mm waste drain**, there are two useful approaches:

- **Drain camera with a locating transmitter (“sonde”).** Feed it into the drain through an accessible cleanout, then use a matching handheld receiver outside the wall to locate the camera head. Moving the head and marking successive positions traces the pipe’s route. Ask a plumber for a *drain camera inspection with sonde locating*. [RIDGID explains locating PVC this way.](https://www.ridgid.com/hn/en/navitrack-scout-locator)
- **Radar wall scanner rated for empty plastic pipes.** Some professional scanners can detect these through a wall, subject to wall construction and detection depth. Check the specifications carefully: models that detect only **water-filled** plastic pipes may miss a waste drain, which is normally mostly empty. [Bosch lists these capabilities separately.](https://www.bosch-professional.com/gb/en/detectors-101302-ocs-c/)

Running water and listening along the wall can help narrow down the route, but does not establish an exact position. If you need to locate the pipe accurately before opening the wall, a sonde is usually the most practical choice when there is drain access.