Best Pressure Washer NZ: Which to Buy
Moss and mould on decking and driveways is a genuine year-round problem in NZ's damp climate. Here's what pressure washer specs actually mean for that job.
Electric vs petrol: the real trade-offs
Electric pressure washers are lighter, quieter, need no fuel or servicing, and are the right choice for most residential jobs — cars, decking, outdoor furniture, small-to-medium driveways. Their main limits are the power cord (you need a nearby outlet or an extension cord) and generally lower sustained pressure than petrol units. Petrol pressure washers deliver significantly more power and aren't tethered to a power outlet, making them better for large concrete areas, farm use, or heavy-duty grime removal — but they're heavier, louder, need fuel and oil changes, and are overkill for a typical suburban section.
PSI and flow rate: what the numbers actually mean
PSI (pressure) measures force, and flow rate — usually listed as L/min or GPM — measures how much water moves through per minute. Both matter together: high PSI with low flow can still take a long time to clean a large area, while a machine with strong flow clears grime faster even at moderate pressure. For context, a household electric unit is typically 1400-2100 PSI, which is genuinely sufficient for cars, decking, and general outdoor cleaning. Concrete driveways with embedded dirt benefit from 2000-3000 PSI or a petrol unit. Anything above that risks damaging softer surfaces like painted decking or older concrete.
NZ's real use case: moss and mould on decking and driveways
New Zealand's damp climate means moss and black mould buildup on north-facing decking, paths and driveways is a genuine, recurring maintenance problem, not a rare one. For this specific job, pressure alone isn't the whole story — a wide fan-spray nozzle set at moderate pressure (not the narrow "turbo" nozzle, which can gouge softwood decking) combined with a detergent attachment for moss-killing chemical treatment gets noticeably better and longer-lasting results than blasting with max pressure alone. Many electric units include a detergent tank or inline injector for exactly this.
Practical buying guidance
- Cars, decking, outdoor furniture, small driveway: a mid-range electric unit (1600-2100 PSI) from Bunnings, Mitre 10 or PB Tech covers it.
- Large concrete driveway, farm or trade use: petrol unit with 2500+ PSI is worth the extra weight and noise.
- Softwood decking: use a fan nozzle, not a turbo/pencil jet, to avoid gouging the timber.
- Detergent/moss-treatment tank: genuinely useful for NZ's damp-climate moss and mould problem.
- Hose length and cord length: check these before buying — short hoses are a common complaint with budget units.