A pool acid wash in Australia typically costs between A$400 and A$900 for a standard suburban pool, with the final figure depending on pool size, how bad the staining is, and whether draining and water disposal are included in the quote. Small plunge pools and courtyard pools often come in under A$500, while larger pools, heavily stained pebblecrete, or jobs with difficult water access can push past A$1,000.
Most of what's written about acid washing online is a generic step list lifted from a cleaning-product brochure, with a price range so wide it's useless for budgeting. This guide breaks down the real cost drivers — surface type, stain severity, disposal rules — and gives you clear criteria for when an acid wash actually solves the problem versus when you're better off paying for a full drain and acid clean.
Short on time? Open this article in your AI tool of choice — it will summarize the post and answer any follow-up questions.
A pool acid wash in Australia usually costs A$400 to A$900 for a standard 40–50m² in-ground pool, including draining, the acid treatment itself, neutralising and a basic refill. Smaller pools and plunge pools (under 25m²) often sit at the A$350–500 end, while larger pools, lap pools or anything over 60m² can run A$800–1,200 or more once disposal and extra scrubbing time are factored in.
Most tradies quote per job rather than per square metre, because the labour is mostly manual scrubbing and the acid itself is a relatively small cost. If the tradie is registered for GST, the quote should include it — ask for a written quote that states whether GST is already built into the number, since a A$600 quote plus GST is a different job to a A$600 quote including GST.
Water refill is usually charged separately, and it's easy to overlook. Refilling a 50,000-litre pool from mains water in most Australian cities adds roughly A$150–300 to your water bill on top of the acid wash quote itself, so factor that in when comparing quotes that include a refill against quotes that don't.
Pool size is the biggest factor, but it's surface area that matters, not volume — a shallow, wide pool takes longer to scrub than a deep, narrow one of the same litreage. Stain severity is the second big driver: light scale and general dullness might need one light acid pass, while heavy calcium build-up, deep algae staining or years of neglect can need two passes, extra scrubbing time and stronger dilution, which adds hours of labour.
Access and disposal add cost that's easy to underestimate. If a pump truck or extra hose length is needed to get drained water and neutralised acid off-site or into an approved disposal point, that's added to the quote. Pools with limited side access, steep sites, or a long walk from the truck to the pool edge typically attract a call-out or access surcharge of roughly A$50–150.
Plaster (also called marblesheen or render) is the most common pool surface in Australia and the most straightforward to acid wash, since the acid reacts predictably with the cement-based finish. Pebblecrete and quartzon surfaces are more textured, so they trap more staining in the pits between pebbles, which usually means a longer scrub time and a slightly higher quote than a smooth plaster pool of the same size.
Fibreglass pools generally can't be acid washed at all, because the acid will strip or dull the fibreglass gel coat rather than clean it — if you've got a fibreglass pool with staining, ask specifically whether the tradie is proposing an acid wash or a fibreglass-safe stain treatment, since these are different jobs with different products and pricing.
Acid washing a pool means draining it completely, then applying a diluted acid solution directly onto the exposed plaster or pebblecrete to strip away the top layer of stains, scale and etched calcium, before rinsing, neutralising and refilling. It's a surface treatment, not a repair — it removes what's sitting on and just below the surface, it doesn't fix cracks, delamination or structural issues underneath.
A competent tradie will inspect the pool dry before starting, checking for hairline cracks, hollow-sounding patches (a sign of delamination) or exposed aggregate that acid could make worse. If the surface looks structurally compromised, a reasonable operator will flag that an acid wash alone won't solve it and a resurface or repair may be needed first.
The pool is drained fully, with the water directed to an approved disposal point rather than the stormwater system — more on those rules further down. Pump, filter and any auto-cleaner lines are isolated or capped so acid can't get drawn back into the equipment, and coping, tiles and surrounding paving are usually covered or hosed down beforehand to limit acid splash damage.
The tradie working in the empty pool wears acid-resistant gloves, eye protection and often rubber boots, since muriatic (hydrochloric) acid causes burns on skin contact and fumes are harmful in an enclosed pool shell. Good ventilation and having a hose running nearby for immediate rinsing if acid splashes are standard safety practice, not optional extras.
The acid is diluted with water — the ratio depends on stain severity, but a common starting point is roughly one part acid to four parts water for light staining, moving stronger for heavy calcium build-up. It's applied and scrubbed section by section with an acid brush, usually working from the shallow end down, so the tradie isn't standing in acid runoff for long periods.
Once the surface looks clean, the acid is neutralised — typically with soda ash or a similar alkaline product — to bring the pH back to a safe range before the residue is rinsed and drained. Skipping or rushing neutralising is one of the more common mistakes on cheap jobs, since leftover acid keeps etching the plaster surface even after the pool looks clean.
Acid washing a pool typically takes one working day for the draining, acid application and neutralising itself, but the full job — from draining to a pool you can safely swim in — usually takes 2 to 4 days once refilling and water balancing are included. The acid wash part is fast; it's the refill and chemical stabilisation afterwards that add most of the calendar time.
Refilling from mains water for a standard 40,000–50,000-litre pool generally takes 8–24 hours depending on your household water pressure and whether you're filling with a single hose or two. After refilling, the water needs to be balanced and typically left to settle for a further 24–48 hours before it's considered safe and comfortable to swim in.
Heavy staining that needs a second acid pass is the most common delay, adding a half-day to a full day of extra scrubbing. Weather is the second — rain during the drained, empty period can be a genuine problem, since an empty pool shell can be at risk of ground movement or "popping" out of the ground in high water-table areas if it rains heavily while it's empty for an extended stretch.
Access issues (a pump truck that can't reach the pool, needing extra hose runs) and disposal permit delays in some council areas can add a day. If you're on tank or bore water rather than mains, refilling can stretch out over several days depending on your tank capacity and bore flow rate, which is worth asking about upfront if timing matters to you.
Acid washing is worth doing when your pool's plaster or pebblecrete surface is stained, scaled or dull but still structurally sound — it restores the look of the surface without the cost of a full resurface. It's a waste of money when the underlying problem isn't staining at all but cracking, delamination or a surface that's simply worn past the point an acid treatment can fix.
A rough rule many pool builders and resurfacers use: if a plaster pool hasn't been acid washed in 5–8 years and is showing heavy calcium or organic staining, an acid wash is usually still the right call. Past that point, or if the plaster itself feels rough, chalky or is visibly thinning, a full resurface tends to be the better spend, since acid washing an already-thin surface can wear it through faster.
Discolouration from algae staining (green, brown or black patches that don't brush off), a general dull or cloudy look to the plaster, and a light film of calcium scale are all good candidates for an acid wash. If the pool surface is otherwise smooth and intact and the issue is purely cosmetic staining sitting on top of the plaster, an acid wash typically brings it back close to original condition.
An acid wash also makes sense if you're already draining the pool for another reason — replacing tiles, fixing a light niche, or repairing the coping — since the marginal cost of adding an acid wash while the pool's already empty is much lower than draining it again later purely for staining.
If there are visible cracks, hollow spots when you tap the plaster, or areas where the surface is lifting or flaking (delamination), an acid wash won't fix it and can make it worse by eating further into already-compromised plaster. Deep, embedded black algae that's grown into pitted or porous plaster over several seasons often needs more than a standard acid wash, sometimes combined with mechanical abrasion or a partial resurface.
If the pool hasn't had an acid wash in well over 8–10 years, or the plaster feels rough and chalky to touch, get a tradie to assess whether a resurface makes more sense financially — an acid wash on very thin, aged plaster can shorten its remaining life instead of extending it.
An acid wash is a surface-cleaning treatment applied to an empty pool to strip stains and scale, while a "drain and acid clean" is often the same core process bundled with other jobs done while the pool happens to be empty — filter cleaning, equipment servicing, tile de-scaling, re-grouting or minor plaster patching. The terms get used loosely, so what matters more than the label is asking exactly what's included in the quote.
A pure acid wash quote should specify draining, acid application, neutralising and refill. A drain and acid clean quote for the same pool might add tile cleaning (removing calcium build-up on waterline tiles), equipment inspection, and sometimes minor grout or coping repairs — which is why a drain and acid clean quote can run A$800–1,800+ against a simple acid wash's A$400–900, even on the same size pool.
Acid washing itself isn't a separately licensed trade in most Australian states, but any business handling and transporting hydrochloric (muriatic) acid needs to follow workplace health and safety rules for hazardous chemicals and dangerous goods transport. A reputable operator will hold public liability insurance and store acid according to the product's safety data sheet — it's reasonable to ask for proof of insurance before an acid job, since a spill or acid burn on your property is a real risk if handled carelessly.
If the job extends into structural pool work — resurfacing, re-plastering, or repairs — that typically falls under state building licensing, such as a swimming pool builder licence through NSW Fair Trading, a QBCC licence in Queensland, or the equivalent through the VBA in Victoria, Building and Energy in WA, or CBS in South Australia. Ask which category your job falls into if you're getting resurfacing work quoted alongside the acid wash.
Drained pool water and used, neutralised acid generally can't be discharged into the stormwater system in Australia, because stormwater runs directly to waterways without treatment and chlorinated or acidic water can harm aquatic life. Most councils require pool water to be discharged to the sewer system, often via a trade waste agreement, or removed off-site by a licensed liquid waste contractor.
Rules vary by council area, and some require the water to be dechlorinated and pH-neutralised (typically to a pH of around 6–9) before it can go to sewer at all, with some councils setting a discharge rate limit so it doesn't overload the local sewer line. It's worth asking your tradie directly how they're disposing of the water and acid residue — a legitimate operator will have a clear answer, and it protects you from any council follow-up if the discharge point is on your property.
Related questions
Free, fixed and written — approved by you before any work begins.