A waterblaster or high-pressure cleaner is an effective way to quickly clean outdoor surfaces. We've tested a range of mains-electric models by blasting away at grimy concrete paths. Find out which perform the best and are easy to use, plus what to consider when buying and using one.
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Performance tests are carried out on a sandstone footpath. The pavers are grey with age, their cracks lousy with moss. We try all the nozzles of every waterblaster and measure how quickly they clean the pavers. The best cleaning speed we achieve is used to calculate performance scores.
Where applicable, we also try the patio/deck cleaner attachments. These are large discs containing a spinning arm to disperse water without any messy blowback, similar to the inside of a dishwasher.
Our ease of use assessment looks at:
The most common domestic units. They run from a mains powerpoint and have enough juice for most cleaning jobs around the home. But you’re limited by the range of the extension cord.
These units are heavier and more expensive, but are usually more powerful and suited for all-day industrial cleaning. You’re only limited by the length of the hose.
Battery-electric models generally only run for 15-20 minutes before needing to recharge, meaning they’re only suitable for small jobs.
Ease of use: Look for a model with spray settings that are easy to adjust. Some require you to let go of the trigger and grasp the lance with both hands, which can be tricky to do.
If possible, test a model out to ensure it's not too heavy for you (models range in weight from 8 to 15 kilograms). Models with wheels and a well designed handle make moving around easy. Make sure the handle is long enough to use easily.
Rotary start/stop switches on the side are much easier to access than recessed rear switches.
Water use: An average garden hose flows water at about 30 litres per minute. The waterblasters we tested were rated at between 5.2 and 8.7 litres per minute – a substantial water saving. If you’re in an area with water metering, using a waterblaster instead of a hose can reduce your water use. It also does a better cleaning job.
Detergent attachment: Many models carry this handy feature, which dispenses detergent in your water spray, for easy window and surfaces cleaning.
Storage features: A lance-holder lets you stow the lance on the machine while not in use. Likewise, a hose storage hook is handy for keeping your hose neatly stored.
Suitable pumps: Entry-level to mid-range domestic units (like most models we test) have air-cooled pumps. They can only be used for a maximum of an hour without overheating and needing a stand-down period of 20 minutes. If you run them for several hours you’ll burn out the pump, rendering the machine useless. For big jobs requiring long spells of blasting, look for a water-cooled pump driven by an induction motor.
Pressure/flow rate: Waterblasters are usually marketed based on their maximum water pressure (measured in psi), but flow rates (L/min) are a better gauge of cleaning performance. That said, we find some models with higher pressures/flow rates are outperformed by smaller units. Our test results are the best gauge of a good ’blaster.
Domestic waterblasters consume around 1700W when blasting. And almost always they'll be connected to the mains by a long extension cord. That cord has to carry over 7 amps of electrical current – so use an extension cord that is rated to 10 amps and is rated for outdoor use.
Be careful with your cladding. Waterblasting claddings made from fibre-cement sheet or stucco is a big no-no. That’s because the high-pressure water can penetrate cladding (or any cracks in its surface). Waterblasting weatherboard, brick, concrete block or steel (“galvanised iron”) cladding is acceptable – as long as the nozzle isn’t too close to the surface (less than 500mm) and the spray isn’t directed closely around door openings, window frames and other openings in the cladding.
Take it easy on timber. You can clean your timber deck with your ’blaster, but use the adjustable nozzle’s lowest pressure setting that will still remove grime, and never bring the nozzle closer than 300mm to the deck as the water jet can penetrate and damage the timber, reducing the deck’s life. Alternatively, try the patio cleaner attachment, but use it on a small, inconspicuous area first to ensure it won’t damage the decking.
Start and store sensibly. Follow the manufacturer’s recommended start-up procedure, as documented in the manual. This usually involves connecting the hose and turning on the tap before switching on the power. When you switch the blaster off, purge the remaining water from the hose by squeezing the trigger before disconnecting the tap. Ensure hoses aren’t kinked before storing the unit, and periodically check and clean the suction filter. NEVER run the unit without water.
Choose cords carefully. Waterblasters only come with about 8m of electrical lead, so you may need an extension cord. But don’t use a long cord of insufficient thickness as this could cause a large voltage drop, reducing performance and potentially damaging the pump. Manufacturers recommend gauges of 1.5mm² up to 10m, and 2.5mm² for 10-30m.
Rotary nozzles produce a pulsating, rotating cone of water. We found they’re the best bet for large areas of heavily soiled surfaces like paving, driveways and other surfaces that aren’t easily damaged by high-pressure water. Rotary nozzles produce noticeable vibration in the lance.
Fan nozzles give you a flat, fan-like spray of water. They’re useful for cleaning painted surfaces like sides of houses, roofs and vehicles. The spray is not as powerful as that produced by a rotary jet. However, take care with painted surfaces, they can be damaged if the spray is held too close.
Fixed-jet or needle nozzles deliver a concentrated “pencil” jet. They’re used for small areas of difficult-to-remove soiling on surfaces that are not likely to be damaged by the high-pressure water (such as concrete or other ceramics).
Patio brush attachments are a common inclusion or add-on for many models. These connect to the end of the lance and feature a rotating nozzle and brush for scrubbing decks and smooth surfaces. They generally work well on smooth surfaces such as decks and tiles, but for rougher surfaces like a concrete path you’re better off using a more focused jet of water.
Car wash brushes and foam nozzles are designed for scrubbing cars and bikes, producing water with much less pressure so you won’t chip your paintwork.
Pay attention to where the nozzle is pointing. High pressure water can cause serious injury if it is directed at people or animals.
Ensure you wear the right gear: sturdy non-slip footwear, wrap-around safety glasses, hearing protection and stout gloves.
Be aware of slippery surfaces, especially when carrying heavy equipment that may affect your balance.
Take care when you move the waterblaster to ensure you don’t block or restrict your work area. Try to keep the work area clutter-free, so that if you do slip and fall, you won’t land heavily or awkwardly on equipment or other obstructions.
If your waterblaster has a 2-stroke motor, take care to avoid its exhaust which can cause serious burns.
Avoid using a waterblaster while on a ladder or the roof if possible. A roof cleaning accessory kit lets you clean the roof while staying on the ground. Other accessories are available to help clean gutters and other hard to reach locations. Waterblasting on the roof should be done by a professional who knows how to correctly use a full harness that is fixed to a properly installed anchor bracket.
If working from a ladder, make sure it is securely positioned and fixed in place so that it can't fall sideways. Maintain 3 points of contact on the ladder at all times (for example, both feet and a hand) and only use the handpiece of the waterblaster from the ladder – don’t attempt to position the waterblaster on the ladder. Ensure you have the right ladder for the job so you don’t have to work from the top 3 rungs. For more information about DIY and ladder safety, visit ACC's website.
Electrical faults can develop in any appliance over time. So when you're using outdoor electrical equipment you must always have a residual current device (RCD) plugged in between the extension cord and the mains socket. The only possible exception is if you know your new switchboard has built-in RCDs.
Place the waterblaster unit where it won't get wet. Don't clean a waterblaster with its own high pressure water jet. Wipe it down with a cloth.
Watch out for damage to your property. Waterblasters, particularly those using a needle jet, can damage soft surfaces like wood and asphalt. Test on a small area first. Pull the lance back, to ease the force of the blast. See the Checklist for more information.
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Check out more of our tests, articles, news and surveys in our Home, heating & renovation section.
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