How do you safely work with high pressure equipment near bystanders?

To work safely with high-pressure equipment near bystanders, you must establish clearly marked exclusion zones, communicate active operations through visible signage and verbal warnings, and ensure anyone in the vicinity wears appropriate personal protective equipment (PPE). These measures are not optional extras — they are fundamental requirements in any professional high pressure water jetting operation. The sections below break down each element of bystander safety in detail, from hazard identification to regulatory compliance.

What are the main hazards of high-pressure equipment for bystanders?

The main hazards of high-pressure equipment for bystanders include:

• Direct injection injuries from water jets
• Being struck by dislodged debris or ricocheting material
• Exposure to hazardous substances loosened during cleaning
• Slip and trip risks caused by wet surfaces and hose runs

At pressures ranging from 500 to 3000 bar “7,252 to 43,511 PSI”, even brief contact with a water jet can cause severe, life-threatening injuries.

What makes these hazards particularly serious is that bystanders often underestimate them. A high-pressure water jet is invisible at close range and produces no obvious warning signs like heat or sparks. A jet operating at 1000 bar “14,504 PSI” can penetrate skin, muscle, and bone within milliseconds. Even at lower pressures, the force is enough to cause deep tissue damage that may not be immediately visible on the surface.

Beyond direct jet contact, bystanders face significant secondary risks. Loose scale, rust, coatings, and debris dislodged during surface preparation can travel at high velocity and strike anyone in the surrounding area. A burst or disconnected high-pressure hose can flail violently, covering a wide radius in seconds — a phenomenon known as hose whip, which is particularly dangerous in confined or busy work environments. In petrochemical or industrial cleaning contexts, the water used may carry hazardous residues that pose serious inhalation or skin contact risks to anyone nearby. High-pressure jetting also generates significant noise levels that can damage hearing without appropriate protection, even for those not directly involved in the operation.

Understanding these risks is the foundation of any effective bystander safety plan. Every person near a jetting operation, regardless of their role, must be treated as someone who needs active protection.

What exclusion zones should be set up around high-pressure jetting work?

An exclusion zone around high-pressure water jetting work should extend far enough to protect bystanders from all foreseeable hazards, including jet deflection, debris scatter, and hose whip. The specific size depends on the operating pressure, nozzle type, and work environment, but a minimum radius of 3 metres “approximately 10 feet” is widely recommended for lower-pressure work, with significantly larger zones required at pressures above 500 bar “7,252 PSI”.

In practice, exclusion zones must be defined before work begins, based on a site-specific risk assessment. Key factors that influence zone size include:

• The operating pressure and flow rate, which determine how far a deflected jet or debris can travel
• The type of surface being cleaned or prepared, which affects the volume and velocity of dislodged material
• Whether the work is taking place in an open area or a confined space
• The presence of reflective surfaces that could redirect the jet
• Wind conditions that might carry mist or debris

Exclusion zones must be physically enforced, not just declared. Use barriers, cones, warning tape, and signage to create a visible perimeter. In busy industrial environments such as petrochemical plants or marine facilities, physical barriers are essential because verbal warnings alone are insufficient in noisy conditions. Access points into the zone should be clearly marked and controlled, with only authorised personnel permitted entry.

For operations at the higher end of the pressure range, such as ultra-high pressure work above 2000 bar “29,008 PSI”, the exclusion zone may need to extend considerably further, and additional shielding or deflection guards may be required to protect adjacent work areas.

How do you communicate active high-pressure operations to nearby workers?

Active high-pressure operations should be communicated to nearby workers through a combination of visual signage, physical barriers, verbal briefings before work begins, and real-time signals such as warning lights or audible alerts during operation. No single method is sufficient on its own, especially in noisy or complex industrial environments.

Before work starts, a toolbox talk or pre-job briefing is essential. This should cover the scope of the jetting operation, the location and size of the exclusion zone, the duration of work, and what nearby workers should do if they need to pass through or near the area. Everyone working in the vicinity, not just the jetting crew, should be included in this briefing.

During the operation itself, warning signs must be posted at all entry points to the exclusion zone, clearly stating that high-pressure water jetting is in progress and that entry is restricted. Barrier tape and physical cordons serve a dual purpose, acting as both a communication tool and a physical deterrent. A trained safety observer should be positioned to monitor the perimeter and intercept anyone approaching the zone. In larger facilities, coordinating with control rooms or adjacent teams via radio ensures that operational status is shared in real time. A horn or alarm sounded at the start and end of jetting provides a clear, unmistakable signal across a noisy site.

Clear communication is especially critical during shift changes, when new personnel may arrive on site unaware that jetting is underway. Handover procedures must explicitly include the status of any active high-pressure operations.

What PPE is required for bystanders near high-pressure water jetting?

Bystanders near high-pressure water jetting operations should wear, at minimum:

• Safety footwear with steel toecaps and slip-resistant soles
• Eye protection such as safety glasses or goggles
• Hearing protection rated to the noise level on site

Depending on proximity to the work and the nature of the substances being removed, additional PPE such as face shields, waterproof outer garments, and gloves may also be required. The exact PPE specification should be determined by a site-specific risk assessment.

It is important to distinguish between the PPE requirements for operators and those for bystanders. Operators working directly with high-pressure jetting equipment require full specialist PPE, including high-pressure protective suits rated for the operating pressure, specialist gloves, and visors. Bystanders, while not in the direct line of work, still face secondary risks that demand meaningful protection.

Eye and face protection is a baseline requirement, with safety glasses or goggles guarding against mist, debris, and splash, and a full face shield offering greater coverage when working in close proximity to the operation. Hearing protection rated to the noise level on site is equally essential, as high-pressure jetting routinely generates noise levels that exceed safe exposure limits. Steel-toecap boots with slip-resistant soles protect against crush injuries and reduce the risk of falls on wet surfaces. In wet environments or where mist exposure is likely, waterproof jackets and trousers prevent prolonged skin contact with contaminated water. A hard hat is required in any environment where overhead work or falling objects are a risk, which is common in industrial maintenance settings.

PPE is always the last line of defence, not the first. It should be used alongside, not instead of, proper exclusion zones and engineering controls.

What should you do if a bystander enters the work zone during operations?

If a bystander enters the work zone during active high-pressure water jetting operations, work must stop immediately. The correct response is:

• Cease jetting and engage the safety trigger lock
• Alert the safety observer immediately
• Guide the bystander out of the zone before any work resumes

Under no circumstances should jetting continue while an unauthorised person is within the exclusion zone.

This response should not be improvised on the day. A clear emergency stop and zone breach procedure should be established as part of the pre-job planning and communicated to the entire team during the toolbox talk. Everyone involved in the operation, including support staff, should know what to do if someone enters the zone unexpectedly.

After the incident, even if no injury occurred, a brief review is good practice. The team should consider why the bystander entered the zone and whether signage was inadequate or poorly positioned. The sufficiency of physical barriers, the positioning of the safety observer, and whether the pre-job briefing reached all relevant personnel are all questions worth examining. Near-miss incidents are valuable learning opportunities, and reporting and reviewing them helps prevent more serious events in the future while supporting a culture of continuous safety improvement on site.

Which regulations govern bystander safety in high-pressure industrial work?

Bystander safety in high-pressure industrial work is governed by a combination of national regulations, industry standards, and guidelines published by specialist organisations. The specific rules that apply depend on your location and sector, but several bodies publish widely adopted standards that form the backbone of safe practice across the industry.

• Netherlands – SIR: The Stichting Industrieel Reinigen sets guidelines and certification standards for industrial cleaning, including bystander protection requirements for high-pressure water jetting operations.
• Europe – EWJI: The European Water Jetting Institute provides pan-European guidance and training standards covering safe working distances, PPE requirements, and zone management.
• UK – WJA: The Water Jetting Association publishes the industry-standard Code of Practice for high-pressure and ultra-high pressure water jetting, which includes detailed bystander safety provisions.
• United States – WJTA: The WaterJet Technology Association publishes recommended practices covering exclusion zones and bystander protection.
• Germany – DIRV: The Deutsche Industrievereinigung Reinigen und Vorbereiten provides standards for industrial cleaning operations with specific provisions for high pressure safety in the vicinity of non-operational personnel.

Beyond these specialist bodies, national occupational health and safety legislation applies in all jurisdictions. In the Netherlands, the Arbowet (Working Conditions Act) sets the legal framework for workplace safety, including the duty to protect bystanders. In the UK, the Health and Safety at Work Act and associated regulations impose similar obligations. Employers and contractors are responsible for ensuring that their operations comply with all applicable standards, not just those of the jetting industry specifically.

Staying current with guidance from these organisations is important, as standards are periodically updated to reflect new research, equipment developments, and incident learnings from across the industry.

How DERC Salotech Supports Safe High-Pressure Water Jetting Operations

At DERC Salotech, we understand that high pressure safety is not just about the equipment itself. It is about the entire system surrounding it, including how it is operated, who is trained to use it, and how bystanders are protected throughout. With over 40 years of experience in high-pressure water jetting technology, we design and engineer solutions that make safe operation as straightforward as possible for maintenance engineers, operators, and field technicians working in demanding industrial environments.

Our approach to supporting safe operations covers every aspect of the work:

• Our systems are precision-engineered to operate reliably within defined pressure ranges from 500 to 3000 bar “7,252 to 43,511 PSI”, reducing the risk of unexpected pressure surges or equipment failures that endanger those nearby.
• Products like the Flexa-Jet Chain Manipulator and the MagTrack robotic system are designed to reduce the need for operators and bystanders to be in close proximity to the jet, improving standoff distances and overall site safety.
• Our range of high-pressure nozzles allows precise control of jet direction and force, minimising uncontrolled deflection that poses risks to nearby workers.
• Through our subsidiary DERC Adviesgroep, we offer certified training courses aligned with the standards of SIR, EWJI, WJA, WJTA, and DIRV, ensuring that your team understands and applies correct bystander safety protocols.
• All our equipment is engineered to meet both metric and SAE standards, making it easier to work within the regulatory frameworks of different countries and sectors.

If you are reviewing your bystander safety procedures or looking for equipment that supports safer operations on site, we are ready to help. Contact our team to discuss your specific requirements and find out how we can support your operations.