Flooded? - Different Water Categories Affect the Level of Damage

Not All Flood Water Is the Same

Flooding in your home can be incredibly stressful—damaged belongings, soaked floors, and the risk of mould growth are all immediate concerns. But did you know that not all floodwater is equal?

The type—or category—of water involved in a flood plays a major role in how dangerous it is to your health, how much damage it causes, and what steps are required for proper cleaning and restoration.

Understanding the three official water categories, as defined by the IICRC (Institute of Inspection Cleaning and Restoration Certification), can help you make informed decisions

after a flood and know when it's time to call the professionals.

Category 1 – Clean Water

What It Is:

Category 1 water is considered “clean water”, meaning it comes from a sanitary source. This might include:

• Burst pipes or water mains

• Overflowing sinks or bathtubs (with no contaminants)

• Rainwater leaks through a roof

Risks:

While Category 1 water poses minimal health risk at the start, it can quickly degrade into Category 2 or 3 if left untreated or if it comes into contact with dirty surfaces.

Damage Potential:

• Minimal contamination

• Drying and dehumidifying may be sufficient

• Still requires quick action to prevent mould

Key Advice: Don’t delay. Even clean water can turn dangerous if ignored for more than 24–48 hours.

Category 2 – Grey Water

What It Is:

Category 2, or “grey water,” contains some level of contaminants that may cause discomfort or illness if ingested. Common sources include:

• Washing machine overflows

• Dishwasher leaks

• Sump pump failures

• Toilet overflows (without faeces)

Risks:

Grey water can contain microorganisms, chemicals, or soaps that may cause skin irritation or illness. If left standing, it quickly deteriorates into Category 3.

Damage Potential:

• Requires disinfection as well as drying

• May cause damage to porous materials (carpets, upholstery, wood)

• Higher risk of mould growth

Key Advice: Category 2 water demands professional extraction and sanitisation to prevent long-term damage and health risks.

Category 3 – Black Water

What It Is:

Category 3 water is heavily contaminated and poses a serious health hazard. Sources include:

• Sewage backups

• Toilet overflows containing faecal matter

• Floodwater from rivers, lakes, or storms

• Water that has been stagnant for days

Risks:

Black water can contain pathogens, toxins, bacteria, and viruses. Contact with this type of water can lead to serious illness or infection.

Damage Potential:

• Affects everything it touches—including walls, floors, and furniture

• Requires complete removal of contaminated materials (e.g., carpets, insulation)

• Demands professional-grade PPE, disinfection, and drying equipment

Key Advice: Never attempt to clean Category 3 water yourself. Call certified professionals immediately.

Why This Matters – Health, Safety, and Recovery

Knowing the water category is crucial because it:

• Determines the urgency and scope of remediation

• Affects what items can be saved or discarded

• Guides insurance claims and documentation

• Protects your health and safety