Jetting in drainage clearance refers to a method used to clear blockages and clean drainage systems using high-pressure water jets. It is a highly effective technique for removing obstructions such as debris, silt, grease, roots, and other accumulated materials from pipes and drains.

Here's an overview of how jetting in drainage clearance works:

1. High-Pressure Water Jets: Jetting machines are equipped with a powerful pump that generates high-pressure water jets. The water is delivered through a specialized nozzle that directs the jet in a controlled manner.

2. Insertion into the Drainage System: The jetting nozzle is inserted into the blocked or clogged drain or pipe. The nozzle is designed to create a forward-facing jet, which propels it through the drain while simultaneously clearing blockages.

3. High-Pressure Water Jetting: As the high-pressure water is released from the nozzle, it creates a strong force that dislodges and breaks apart the blockage. The force of the jet can remove debris, sediment, tree roots, grease, and other materials that may be obstructing the flow.

4. Thorough Cleaning: In addition to clearing the blockage, jetting also cleans the interior surfaces of the pipes. The high-pressure water jets can remove scale, mineral deposits, and other build-up, restoring the flow capacity of the drain or pipe.

5. Inspection and Verification: Once the jetting process is complete, a follow-up inspection may be performed to ensure the blockage is fully cleared and the drainage system is functioning properly. CCTV drainage surveying (as mentioned earlier) can be used to assess the condition and integrity of the pipes.