Water blasting is one of the most effective ways to restore hard outdoor surfaces, yet it’s also one of the most misunderstood exterior cleaning services. Many homeowners worry about surface damage, pressure levels, mess, water use, and whether water blasting is actually safe for concrete, pavers, and patios.

These are valid concerns. Used incorrectly, water blasting can damage surfaces and create more problems than it solves. Used correctly, it is one of the fastest, safest, and most cost-effective ways to restore outdoor areas.

This guide answers the most common water blasting questions homeowners ask across New Zealand, explaining exactly how professional water blasting works, what it should and should not be used for, and what results you can expect.

What Is Water Blasting Used For?

Water blasting is designed specifically for hard, non-painted surfaces.

It is commonly used to clean:

  • Concrete driveways

  • Footpaths and pathways

  • Patios and courtyards

  • Pavers and paving stones

  • Steps and landings

  • Retaining walls

  • Garage floors

  • Commercial hardstand areas

Water blasting is not used for:

  • House washing

  • Roof cleaning

  • Painted walls

  • Delicate cladding

These surfaces require soft washing instead.

Is Water Blasting the Same as Pressure Washing?

Yes — in New Zealand, the terms are often used interchangeably.

However, professional water blasting differs from DIY pressure washing in key ways:

  • Pressure is adjusted to suit the surface

  • Correct nozzles are used

  • Distance from the surface is controlled

  • Runoff is managed properly

It’s not about maximum pressure — it’s about controlled pressure.

How Much Pressure Is Used in Professional Water Blasting?

Pressure varies depending on the surface being cleaned.

Professional operators adjust:

  • PSI (pressure)

  • Flow rate

  • Nozzle angle

  • Distance from the surface

Concrete can handle more pressure than:

  • Pavers

  • Decorative finishes

  • Aged or cracked surfaces

Using excessive pressure is one of the most common causes of damage in DIY cleaning.

Can Water Blasting Damage Concrete?

Yes — if done incorrectly.

Concrete can be damaged by:

  • Excessive pressure

  • Holding the nozzle too close

  • Using narrow, aggressive nozzles

  • Repeated passes over weak areas

Damage can include:

  • Surface pitting

  • Aggregate exposure

  • Etching

  • Accelerated deterioration

Professional water blasting cleans effectively without removing the surface layer.

Why Does DIY Water Blasting Sometimes Leave Lines or Marks?

Striping or “tiger lines” are caused by:

  • Inconsistent nozzle movement

  • Incorrect pressure settings

  • Uneven cleaning patterns

Professionals use:

  • Surface cleaners for large areas

  • Consistent overlapping passes

  • Correct speed and spacing

This ensures an even, uniform finish.

Is Water Blasting Safe for Pavers?

Yes — when done correctly.

Pavers require:

  • Lower pressure than concrete

  • Wider spray angles

  • Careful joint protection

Incorrect water blasting can:

  • Remove jointing sand

  • Cause pavers to loosen

  • Create uneven surfaces

Professional cleaning preserves paver integrity and appearance.

Will Water Blasting Remove Weeds Between Pavers?

Yes — temporarily.

Water blasting:

  • Removes visible weeds

  • Clears dirt and organic matter from joints

However:

  • Weed seeds remain in the environment

  • Regrowth can occur

Many homeowners choose to:

  • Re-sand joints after cleaning

  • Apply weed control as maintenance

Can Water Blasting Remove Mould and Algae?

Yes.

Water blasting is very effective at removing:

  • Green algae

  • Slippery biofilm

  • Surface mould

This is especially important for:

  • Driveways

  • Steps

  • Paths

  • Pool surrounds

Removing algae significantly improves safety by reducing slip risk.

Is Water Blasting Slippery Areas a Safety Improvement?

Absolutely.

Slippery outdoor surfaces are one of the most common causes of:

  • Slips

  • Falls

  • Injuries

Water blasting restores surface grip and is one of the quickest ways to make outdoor areas safer.

Can Water Blasting Remove Oil Stains?

Partially — depending on the stain.

Fresh oil stains respond better than old, set-in stains.

Oil removal may require:

  • Degreasers

  • Hot water

  • Multiple treatments

Some deep oil stains may lighten significantly but not disappear completely.

Can Water Blasting Remove Rust Stains?

Sometimes — but not always fully.

Rust stains may require:

  • Specialised treatments

  • Acid-based products

  • Controlled application

Water blasting alone may reduce surface staining but not eliminate deep rust marks.

Is Water Blasting Safe Around the House Foundation?

Yes — when done properly.

Professional operators:

  • Control water direction

  • Avoid forcing water into gaps

  • Manage runoff away from foundations

Uncontrolled DIY blasting can push water where it shouldn’t go.

How Much Water Does Water Blasting Use?

Water blasting is efficient when done correctly.

While high flow is used, jobs are:

  • Completed quickly

  • More effective than repeated low-pressure attempts

In many cases, professional cleaning uses less total water than extended DIY cleaning.

Does Water Blasting Make a Mess?

It can — but professionals manage it.

Professional water blasting includes:

  • Directional control

  • Runoff management

  • Cleanup of debris

Loose dirt and organic matter are removed rather than spread around the property.

Should I Remove Outdoor Furniture Before Water Blasting?

Yes — it’s recommended.

Items to move include:

  • Outdoor furniture

  • Mats

  • Pot plants

  • Decorative items

This ensures:

  • Full cleaning coverage

  • No splashback staining

  • Faster completion

How Long Does Water Blasting Take?

Time depends on:

  • Surface area

  • Level of buildup

  • Type of surface

Typical jobs take:

  • 1–3 hours for residential areas

  • Longer for large or heavily stained surfaces

Do I Need to Be Home During Water Blasting?

Not usually.

As long as:

  • Access is available

  • Pets are secured

  • Vehicles are moved

Work can be completed without the homeowner present.

Can Water Blasting Be Done in Any Weather?

Best conditions are:

  • Dry weather

  • Minimal wind

Light rain is often manageable, but heavy rain may reduce effectiveness and visibility.

How Often Should Driveways and Paths Be Water Blasted?

General guidance:

  • Every 12–24 months

  • More often for shaded or damp areas

  • As soon as surfaces become slippery

Regular cleaning prevents heavy buildup and surface damage.

Is Water Blasting Better Than Chemical Cleaning for Concrete?

They serve different purposes.

Water blasting:

  • Removes surface buildup

  • Improves appearance immediately

  • Restores grip

Chemical treatments:

  • May assist with stains

  • Are often used alongside blasting

Professional services choose the right method for each surface.

Why Professional Water Blasting Is Worth It

Professional water blasting:

  • Prevents surface damage

  • Delivers even results

  • Improves safety

  • Extends surface lifespan

Poor technique often leads to costly repairs or replacement.

What Should I Do to Prepare Before Water Blasting?

Preparation is simple:

  • Move vehicles

  • Remove outdoor items

  • Secure pets

Everything else is handled professionally.

What Surfaces Should Never Be Water Blasted?

Water blasting should NOT be used on:

  • House exteriors

  • Roofs

  • Painted surfaces

  • Delicate cladding

These surfaces require soft washing, not pressure.

Request a Quote for Professional Water Blasting

If your driveway, paths, or patios are dirty, slippery, or stained, professional water blasting is the safest way to restore them.

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https://www.metrowaterblasting.co.nz/

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0800 997 997

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