Hydro Probing

HYDRO PROBING uses pressurized water with a minimal amount of vacuum to probe in the ground. With the exception of the use of water and vacuum, the technique is identical to probing with a probing iron. This is often done to provide clearance support to engineers and contractors but can also be used to pin point certain utilities with virtually no disturbance to the ground. While the probing application can be very cost-efficient, if your hydro excavation contractor has any integrity at all, they will be quick to point out one very important drawback to this approach:


Putting iron on it is no substitute for putting light on it. With light, you know what you are seeing. With just the tip of a probing lance, there is virtually no way to distinguish the encountered object as a utility. It could be a frivolous rock, brick or piece of wood. It could be part of an old concrete slab. It could be anything.

Because probing can involve direct contact with underground utilities, there is the added risk of damage to pipeline coatings.

Probing can also create a false sense of clearance, especially when nothing is encountered below the surface. It is possible to conduct twenty or thirty probes in a 60″ diameter and never detect a 2″ gas line. The probability of this increases dramatically with the depth of the probe. Additionally, how does one distinguish between a quarter-inch fiber optic cable and a root? Guess?

Hydro probing offers no certainty about the presence or absence of underground utilities. The best application of this process is pre-hydro excavation probing, which can be used to spot large diameter structures and utilities prior to hydro excavating to uncover the utility.

In the hands of an experienced operator, hydro probing can be used quite effectively in conjunction with other hydro excavation techniques to expedite large scale projects without jeopardizing safety. A good contractor will do more than perform the requested work; they will make every effort to assure that the client fully understands the risks of hydro probing and is aware of other approaches that will safely achieve the desired goal.