waterdamagequotesWater categories and drying classes, explained
Every Australian scope of works carries two labels: a category and a class. They mean different things, they are decided separately, and between them they explain why two jobs of identical size can differ in price by a factor of five.
Every scope of works an Australian restoration company writes has two labels on it: a category and a class. They mean different things, they are decided separately, and together they explain why two jobs of identical size can differ in price by a factor of five.
A note on where this comes from. The framework is ANSI/IICRC S500, which is a paid standard. Its text is not reproduced anywhere on this site. What follows is how Australian restorers describe the categories in their own published material — Reztor Restoration, for instance, describes assessing “the source and category of water damage” and using in-place drying aligned to S500. If you need the standard itself, buy it from the IICRC.
Category: how contaminated the water is
Category 1
Water from a sanitary source that poses no substantial threat on contact. In an Australian house that means a supply line, a cistern feed, a hot water unit inlet, a dishwasher or washing machine supply, or clean rainwater that has not passed over a contaminated surface.
What it means for the job: carpet and underlay can often be dried in place; plasterboard and cabinetry usually survive if drying starts promptly; disposal is minimal.
Category 2
Water carrying enough contamination to cause discomfort or illness on contact. A washing machine or dishwasher discharge, a shower or basin waste, an overflowed toilet with urine but no faeces, or Category 1 water that has sat and begun to degrade.
What it means for the job: underlay normally goes; carpet may be salvageable with antimicrobial treatment; wet plasterboard is more likely to come out; HEPA filtration starts appearing on the scope.
Category 3
Grossly contaminated. Sewage, water from outside the building including flood water and ground surface water, sea water, and anything that has stood long enough to go septic.
What it means for the job: porous materials are removed and disposed of rather than dried; containment and negative air pressure; PPE; reinstatement of everything removed. This is the expensive one and the expense is not the drying.
The escalation is the important part
Category is not a property of the water at the moment it arrives. It is a property of the water now. Clean supply water sitting in a warm Australian subfloor with organic matter in it is not Category 1 three days later, and it will not be treated as such by anyone writing a scope.
The practical arithmetic: on the published rate card this site reproduces, an extra two days of drying with four air movers and two dehumidifiers is $1,148 excluding GST. Letting a Category 1 job become a Category 2 job costs considerably more than that, because now the underlay and the plasterboard are coming out. That is the entire commercial argument for responding on day one and it is a real one.
Day one is cheaper than day four
Four digits and restoration companies advertising for your postcode call you.
Class: how much is wet, and how hard it will be to dry
The second axis, and the one that sets how many machines turn up. Category is about contamination; class is about the drying problem. The four classes, as Australian restorers use them:
| Class | The situation | What it means |
|---|---|---|
| Class 1 | A small part of the area is wet, and mostly into low-porosity materials | The easiest drying problem. Few machines, short duration |
| Class 2 | A substantial part of the area is wet, water has wicked up walls, carpet and underlay are saturated | The common domestic case. Air movers and dehumidification across the affected rooms |
| Class 3 | Water came from above — the whole assembly is wet including ceilings, walls, insulation and floors | More machines, longer, and ceiling cavities have to be addressed |
| Class 4 | Deeply held moisture in low-permeance materials: hardwood, concrete, plaster, masonry, stone | Specialty drying, longer duration, sometimes injection or heat drying |
Class 4 is the one that quietly blows out a budget. Water that has gone into a concrete slab or a solid timber floor does not come out on a four-day schedule, and a job that was quoted as Class 2 and turns out to be Class 4 doubles in duration. Every day of extension is another multiple of the published daily hire rate.
Reading a scope of works
When a quote or a scope arrives, these are the things to look for, in this order:
- The category, stated. If it is not on the document, ask. It is the single number that determines what is being thrown away.
- The class, or the equipment count. How many air movers, how many dehumidifiers, and how many days. That is the arithmetic of the invoice and it is checkable against published rates.
- What is being removed, itemised. Underlay, plasterboard to what height, insulation, skirtings, cabinetry.
- Whether monitoring is included. Daily readings, and a final moisture report. Without that last document you cannot prove the building was dry when the equipment left, and that matters if mould appears later.
- What reinstatement is and is not in scope. Most drying quotes stop at dry. Putting the building back is a different trade and often a different contract.
Ask every company for the same five items. Then their numbers are comparable, which in this market they usually are not. A quote that is a single figure with no category, no equipment count and no day count is not a quote, it is a number.
How category interacts with the claim
The category does not change whether the event is covered — that is decided by the cause, under reg 19(1)(a)(vi), reg 19(1)(a)(xiv) or reg 34(1). What it changes is the size of the loss and therefore how much of it the policy limits and sub-limits reach.
Two places it matters directly. Category 3 jobs generate mould risk, and most policies cap mould at a sub-limit — see the mould page. And Category 3 jobs frequently make the home uninhabitable, which is a temporary accommodation benefit that is not paid unless it is claimed.
Get a scoped quote, not a number
Ask for the category, the equipment count and the day count. Then you can check the arithmetic yourself against the published rates on this site.
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Here is what happens after you submit:
- Your answers go to restoration companies that advertise for your postcode.
- No more than three of them may contact you, using the details you gave.
- You decide who, if anyone, you use. You are committed to nothing, and this does not lodge, alter or affect an insurance claim.
We are not a restoration company and we do not attend, assess or repair anything.
Common questions
What are the three categories of water damage?
Category 1 is water from a sanitary source. Category 2 carries enough contamination to cause discomfort or illness. Category 3 is grossly contaminated. The categories are from ANSI/IICRC S500, a paid standard whose text is not reproduced here.
Can Category 1 water become Category 3?
Yes, and it is the single most important thing to understand about them. Category is not fixed at the moment the water arrives -- it moves with time, temperature and what the water is sitting in. Clean water in a warm Australian subfloor does not stay Category 1 for long.
What are drying classes?
A separate axis from category. Category describes how contaminated the water is; class describes how much material is wet and how hard it will be to dry. A small amount of water into low-porosity materials is a different drying problem from a whole floor of saturated carpet.
Why does the category change the price?
Because it decides whether porous materials are dried or disposed of. The equipment is broadly the same across all three; the removal, disposal, containment and reinstatement are not.
Why does this site not quote the S500 standard?
ANSI/IICRC S500 is a paid standard. Reproducing its text would be a copyright problem and pretending to have read it would be worse. What is described here is how Australian restoration companies use the framework in their own published material.
Sources cited on this page
- NSW Health, Mould factsheet
- Reztor Restoration, published call-out fee
- QLD Flood Restoration, published equipment hire and extraction rates
- Insurance Contracts Regulations 2017 (Cth)
Every figure above was read from the source it is attributed to on 20 September 2026. How we check this.