What is a Jetting

Jetting, also known as High-Pressure Water Jetting, is a widely used technique for clearing and cleaning drains, sewers, and pipe systems using a concentrated stream of high-pressure water. The method involves directing pressurised water through a flexible hose and specialised nozzle to break down blockages, remove debris, and restore flow within the pipework.

Jetting is one of the most effective and non-invasive methods of maintaining underground drainage infrastructure and is widely employed across domestic, commercial, and municipal drainage systems. It is suitable for both reactive maintenance, such as emergency blockage removal, and planned preventative maintenance to ensure optimal system performance.

How Jetting Works

The jetting process begins with the insertion of a jetting hose into the affected pipe via an access point such as an inspection chamber or manhole. At the end of the hose is a jetting nozzle that emits high-pressure water in multiple directions:

  • Forward-facing jets cut through and dislodge blockages.
  • Rear-facing jets propel the nozzle through the pipe and clean the inner walls as the hose is retracted.

Water is delivered from a jetting machine, often mounted on a van or trailer, capable of generating pressures from 1,500 psi (100 bar) to over 10,000 psi (700 bar) depending on the application.

As the water scours the pipe interior, debris is broken up and either flushed downstream or collected for removal.

Applications of Jetting

Jetting is used in a wide range of drainage maintenance and rehabilitation tasks, including:

  • Unblocking drains obstructed by grease, scale, silt, wet wipes, or tree roots.
  • Cleaning sewers to prepare them for CCTV inspection or relining.
  • Clearing gullies and channels in roads and industrial yards.
  • Removing scale or sediment in pressure pipes and siphons.
  • Restoring hydraulic capacity in underperforming or ageing pipe networks.

In large-diameter sewers, jetting may be combined with vacuum tankers to extract loosened debris, especially in commercial or municipal settings.

Advantages of Jetting

Jetting is considered a preferred method for drain cleaning due to several key advantages:

  • Highly effective at clearing both soft blockages (grease, sludge) and hard obstructions (scale, debris).
  • Non-destructive when used correctly — does not damage the pipe structure.
  • Environmentally friendly, as it typically requires no chemicals.
  • Versatile, suitable for pipes of various sizes, materials, and configurations.
  • Quick and efficient, reducing system downtime and disruption.

It is particularly valuable in urban and built-up environments, where excavation to access buried pipes would be costly and disruptive.

Safety and Operational Considerations

High-pressure water jetting must be carried out by trained and certified personnel, as the equipment involves powerful forces that can cause injury or damage if mishandled. Operators are typically trained to Water Jetting Association (WJA) standards in the UK.

Important safety and operational measures include:

  • Personal protective equipment (PPE): Eye protection, gloves, boots, and waterproof clothing.
  • Site risk assessment: Ensuring public and operator safety around jetting operations.
  • Backflow prevention: To avoid water returning into clean areas or buildings.
  • Correct nozzle selection: Based on pipe material, size, and blockage type.

Overuse or misuse of jetting, especially in fragile or defective pipes, can cause structural issues. Therefore, pre-jetting CCTV inspection is sometimes carried out to assess pipe condition.

Limitations

While jetting is highly effective, it is not always suitable for every drainage issue:

  • Collapsed pipes or major structural defects cannot be cleared by jetting and require excavation or repair.
  • Persistent root ingress may require mechanical cutting or root-resistant relining.
  • Low-flow systems may not allow effective removal of dislodged debris without supplementary extraction or suction.

In such cases, jetting is often used in conjunction with other methods for a complete solution.

Jetting in Preventative Maintenance

Jetting is not only used for emergency unblocking — it plays a vital role in Planned Preventative Maintenance (PPM) programmes. Regular jetting of high-risk areas, such as commercial kitchens, food processing plants, and heavily trafficked drainage networks, helps:

  • Prevent blockages and overflows
  • Extend the life of the drainage system
  • Maintain compliance with environmental and health regulations
  • Reduce emergency call-outs and associated costs

Jetting frequency in such settings is often determined through initial inspection and ongoing system monitoring.

Conclusion

Jetting, or high-pressure water jetting, is a cornerstone of modern drain and sewer maintenance. It provides a powerful, safe, and environmentally responsible way to clear blockages, clean pipework, and maintain the flow capacity of drainage infrastructure. Whether used for emergency response or part of a regular maintenance regime, jetting is an indispensable tool for drainage engineers, local authorities, and property managers committed to ensuring the long-term performance and reliability of underground systems.