Coating removal, hydrodemolition, industrial descaling and surface preparation - work where the alternative is abrasive blasting or mechanical breaking.

Coating removal is the largest application. Water jetting strips paint and corrosion products from steel without introducing abrasive, so there is no spent grit to collect and dispose of and no dust cloud. It also cleans out pitting that abrasive bridges over.

Hydrodemolition removes deteriorated concrete selectively. The jet breaks out weak and damaged material while leaving sound concrete and reinforcement intact and undamaged - something a breaker cannot do, since percussion micro-fractures what it leaves behind.

Process cleaning covers heat exchangers, tanks, pipework and vessels where hard deposits have to come off without attacking the substrate.

It is also used for cutting, and in some industries for removing material in environments where sparks or heat cannot be tolerated.

Extremely dangerous, and the controls are formal: trained and certificated operators, exclusion zones, dead-man controls, inspected hoses, and a documented emergency plan with the nearest hospital informed in advance.

The jet cuts flesh instantly and injects water and contaminants deep into tissue. The entry wound can look like a small puncture while the damage beneath requires immediate surgery. Every operator and supervisor must know that an injection injury is a surgical emergency and must say so at the hospital.

Controls that are not optional anywhere: a dead-man or trigger device that dumps pressure the instant it is released; an exclusion zone that no untrained person can enter; hoses and fittings certified for the pressure and inspected on a schedule; and protective equipment specified for jetting rather than general PPE.

Reaction force must be managed by equipment design or by mechanised delivery, not by operator strength.

The governing rules are jurisdiction-specific. Establish the local requirement for operator certification and equipment inspection before any work is planned.

Selective removal of deteriorated concrete by high-pressure water, specified when sound concrete and reinforcement must survive the process intact.

A breaker removes concrete by percussion, which fractures the material it leaves behind and can damage or displace reinforcement. On a repair, that means the new material is bonded to a damaged substrate.

Water removes only what is weak. Sound concrete resists the jet; deteriorated, delaminated or chloride-damaged material breaks out. Reinforcement is cleaned rather than cut, and the resulting surface is rough and clean - close to ideal for bonding a repair.

It is common on bridge decks, marine structures, car parks and any reinforced concrete repair where the specification calls for a defined removal depth or a bond-ready surface.

The trade-offs are water volume, containment and treatment of the runoff, and noise. All three have to be planned before mobilisation.

No spent abrasive, no dust, and it cleans pitting properly - but it leaves the surface wet and does not create a profile where none exists.

Abrasive blasting generates a large volume of contaminated spent media that has to be collected and disposed of, often as hazardous waste when the coating contained heavy metals. Water jetting produces only water and coating debris, which is a much smaller disposal problem, though still one that requires containment.

Jetting removes soluble salts from the surface, which blasting does not - and residual salt is a common cause of premature coating failure.

The limitation is profile. Water removes the coating and corrosion products and reveals the existing surface profile; it does not cut a new one into bare steel. Where the specification demands a particular anchor pattern on previously smooth steel, abrasive is still needed.

Flash rusting on the cleaned steel has to be managed with inhibitors or a tight coating window.

Formal, recognised jetting training, refreshed periodically, with separate competence for supervisors - and the specific scheme depends on the jurisdiction.

Most industrial regions operate a recognised certification scheme for high-pressure and ultra-high-pressure water jetting, typically covering safe systems of work, equipment checks, hazards, emergency procedures and practical operation.

Supervisors usually need an additional qualification, because much of the risk control sits in planning: exclusion zones, permits, communications and rescue arrangements.

Certification generally has an expiry and requires refresher training, and clients routinely audit it before allowing work on site.

Beyond the certificate, equipment-specific familiarisation matters. Controls, dump systems and gun designs differ between manufacturers and an experienced operator on unfamiliar equipment is still a risk.

Confirm the scheme recognised by the local regulator and by the client before mobilising.

The industry divides broadly into high pressure for cleaning, ultra-high pressure for coating removal and cutting, and a very high band for specialist work - with the boundaries defined differently by different national standards.

Cleaning-class equipment overlaps with heavy industrial washers and is used for descaling, tank cleaning and general industrial soil.

Ultra-high pressure is where coating removal, hydrodemolition and cutting live. Flow is usually modest, because the energy is in the pressure rather than the volume, and that changes hose, fitting and control requirements completely.

Flow still matters. Higher flow at a given pressure removes material faster and drives rotating heads and multi-jet tools that would stall on a low-flow unit.

Because national standards set the boundaries differently, specify the work to be done and the standard to be achieved, and let the supplier match equipment to it - a pressure figure alone does not describe the job.

With physical containment, vacuum recovery and a treatment route agreed before work starts - because the runoff usually carries whatever was removed.

Coating removal produces water contaminated with the coating, which historically may contain lead, chromate or other regulated substances. That water cannot go to a drain, and in many jurisdictions is a controlled waste from the moment it is created.

Containment is usually a combination of sheeting or shrouding at the work face, bunding at ground level, and vacuum recovery collecting water and solids as they are produced. Enclosed and robotic systems recover at the tool.

Recovered water is settled, filtered and either treated for discharge under consent or removed by a licensed contractor. Solids are usually classified separately.

Hydrodemolition produces high volumes of water with fine cementitious solids and a high pH, which normally needs neutralisation before any discharge is permitted.

Agree the disposal route and the consents in the planning stage; it frequently determines the method.