Pressure Washing / High-Pressure Cleaning

A high-pressure injection injury occurs when the water jet penetrates the skin and forces water, air, and contaminants into deep tissues. At pressures above 1,500 PSI, water can easily pierce skin. The wound appears deceptively minor — often just a small puncture mark — but the internal damage is devastating: massive tissue destruction, compartment syndrome (dangerous pressure buildup in muscles), nerve and blood vessel damage, and severe infection from contaminated water forced into deep tissues. 30 % of pressure injection injuries result in amputation. This is a surgical emergency requiring immediate emergency department assessment and likely emergency surgery — even if the wound looks minor. Always carry an injection injury information card for ED staff, as many emergency doctors are unfamiliar with this injury type.

There is no general pressure washing licence in Australia. However, equipment classification under AS/NZS 4233.1:2013 determines training requirements: Class A machines (under 5,600 bar·L/min output — this covers most residential and commercial pressure washers) require documented training but no formal certification. Class B machines (over 5,600 bar·L/min — industrial/commercial water jetting systems) require certified operator training through a registered training organisation (RTO). All operators need documented competency refreshed every 2 years. The unit of competency PRMCL20B (Clean using pressure washing) is available through RTOs.

Absolutely not. It is illegal and extremely dangerous to use high-pressure water on asbestos-containing materials. High-pressure water breaks asbestos fibres into microscopic particles that become airborne and are inhaled, causing mesothelioma (fatal cancer), asbestosis, and lung cancer. SafeWork NSW has issued specific safety alerts about pressure cleaning asbestos roofs. Before pressure washing any building constructed before 2003, confirm the asbestos status of all surfaces. If asbestos is present, engage a licensed asbestos removalist before any cleaning work.

Correct pressure selection prevents both surface damage and injury: Concrete driveways can handle 2,000–3,000 PSI for heavy soiling (800–1,200 PSI for light cleaning). Brick pavers tolerate 1,200–2,000 PSI. Asphalt is delicate — maximum 1,500 PSI. Timber decks are the most sensitive: softwood (cedar, pine) only 500–600 PSI maximum, general hardwood 500–1,000 PSI, composite decking 1,500–2,000 PSI. Always start at the lowest effective pressure and increase gradually. Use wider fan nozzles (25° or 40°) rather than pencil jets (0°) for surface cleaning. Maintain at least 30–45 cm (12–18 inches) distance between nozzle and surface.

In Australia, chemical-laden wastewater from pressure washing must not enter stormwater drains. Stormwater flows directly to waterways without treatment. Before starting work, identify and cover nearby stormwater drains with absorbent booms or drain covers. Direct all runoff to garden/lawn soakage areas where it can be absorbed by soil. If using chemicals (detergents, degreasers), contain and manage all runoff. Some commercial operations require specific environmental licences from the local council or EPA. Water restrictions also vary by location and season — check your local water authority guidelines for any restrictions on pressure washer use.

Minimum PPE includes: both safety glasses AND full face shield (AS/NZS 1337.1), hearing protection (AS/NZS 1270 — Class 3–4 minimum), waterproof safety boots with non-slip soles and steel/composite toe (AS/NZS 2210.3), waterproof protective clothing (full-length trousers and jacket), and chemical-resistant gloves when handling detergents. Sun protection (SPF 50+, hat, UPF clothing) for outdoor work. Hi-vis clothing (AS/NZS 4602.1) when working near traffic. The face shield is critical — it protects against high-velocity water rebound, concrete chips, and chemical splash that safety glasses alone cannot fully prevent.