How do you clean a home after water damage or a fire?

Not all water from an incident is treated the same way, and the category decides what can be washed and what has to be thrown away.

• Clean water — a burst mains pipe, an overflow from a clean cistern, a water heater leak. No contaminants to start with. It becomes grey water within 24 to 48 hours through contact with materials and dust.
• Grey water — a washing machine, a dishwasher, shower run-off, terrace run-off carrying soil. Contaminated but not septic. It turns black within 48 hours.
• Black water — sewage backflow, a septic tank rising, outdoor floodwater that has crossed a road. Loaded with pathogens. Any soaked porous material is a write-off: carpet, mattress, chipboard, insulation.

This classification is not theoretical: it decides what your insurer will agree to replace rather than have cleaned. A mattress soaked by clean water and extracted within hours is recoverable; the same mattress after contact with black water is not.

This is the one point where urgency is genuinely justified.

Mould spores are present in the air at all times. They need three conditions to develop: moisture, an organic material — plasterboard, wallpaper, wood, textiles — and a moderate temperature. Once all three are present, colonisation typically starts between 24 and 72 hours, and 48 hours is the operational benchmark used in the trade.

What has to happen in that window, and what is not cleaning:

1. Cut off the water supply, and the electricity to the affected area if water has reached electrical points.
2. Photograph every room and every item affected, dated, from several angles, before anything is moved.
3. Extract standing water with a wet-and-dry vacuum, without cleaning or throwing anything away.
4. Open up: cupboard doors, drawers, removable skirtings, shutter boxes. Water trapped behind a low unit or under a skirting is what triggers mould three weeks later.
5. Ventilate and get the air moving.
6. Notify the insurer within the timeframe set out in the policy.

The actual clean, meanwhile, waits for the loss to be recorded and the assessor's visit: it is the insurer who decides what will be replaced and what will be cleaned.

Sorting is done material by material, and it has to be documented with photographs before anything is removed.

What almost always has to be thrown away after prolonged soaking

• Chipboard and MDF — kitchen units, carcasses, skirtings: they swell, break down and never recover.
• Fibrous insulation in a wall or ceiling: it holds water and becomes a breeding ground for mould.
• Plasterboard soaked more than a few centimetres up: the card facing is an organic material that has soaked up water.
• Mattresses and upholstered bed bases in contact with grey or black water.

What can be cleaned and recovered

• Tiles, porcelain stoneware, stone, concrete: washing, rinsing, drying.
• Soft furnishings and rugs touched by clean water, treated by hot-water extraction, which removes the contaminated water instead of leaving it in the fibre.
• Solid wood and joinery, provided it has dried without warping.
• Washable surfaces: tiling, glass, metal, plastic.

What gets dried and monitored: slabs, screeds and partition walls. Drying them out is a separate trade in its own right, with moisture readings and dedicated equipment, handled by a specialist company.

Soot is not black dust. It is a greasy deposit, carrying acidic compounds, that keeps attacking surfaces until it is removed: brass, aluminium, painted surfaces and textiles start marking within days.

The order, and it is not intuitive:

1. Fine-filtration vacuuming, the nozzle held without touching the surface. Touching soot with a nozzle presses it into the surface.
2. Dry removal with a soot sponge — a dry, non-abrasive sponge that lifts soot by adhesion. Work from ceiling to floor, in one direction, turning the sponge's face as soon as it is loaded.
3. Degreasing washable surfaces only, once most of the deposit has been removed dry.
4. Rinsing and drying.

The three moves that make it worse: rubbing it dry with a cloth, which embeds it; wiping with a damp cloth first, which spreads the grease and doubles the affected surface; and waiting, because the deposit sets and the acidity keeps working.

The heat of a fire also distorts materials: melted plastic, a cooked seal or a cracked pane are a replacement job, not a cleaning one.

This is the point where promises are easiest to make, which is why the limits need setting out.

What clears with cleaning: the odour carried by the deposit itself. Removing soot from a washable surface removes that surface's odour. Extracting the water and silt from a textile by hot-water extraction removes its musty smell, provided the work happens before colonisation sets in.

What does not clear with cleaning: the odour absorbed into porous materials — a plaster wall, raw wood, insulation, a carpet underlay, upholstery padding. The odour molecules are absorbed there, and no amount of surface product draws them back out.

What actually resolves those cases: removing the affected material, then rebuilding. That is a decision for the insurer and a building contractor, not a cleaning company. A serious quotation flags it, explicitly separating what is recoverable from what is not.

Be wary of ozone treatment or fogging presented as a lasting deodorising fix: masking an absorbed odour only brings it back as soon as humidity rises again.

An insurance case involves four trades, and the order is not negotiable.

1. Leak tracing and making safe — plumber, electrician.
2. Loss recording and assessment — the insurer. A room cleaned before the assessor's visit is a room whose extent of damage can no longer be established.
3. Structural drying — a specialist company, with moisture readings on the affected surfaces. It governs everything that follows: repainting a wall that is not yet dry means redoing it six months later.
4. Rebuilding work — plasterer, painter, tiler, electrician.
5. Final clean — last, once everything else is closed.

Hence a rule that policyholders often discover too late: there are two cleaning visits, and the first does not replace the second.

• The extraction visit, within 48 hours: removing standing water and silt, with no rebuilding work.
• The final visit, after the building work: once rebuilding is finished, the rubble is out and only floors and surfaces are left to clean, it is a post-construction clean, described on our post-construction cleaning page. It comes once soot, mould and water have been dealt with by the right specialists.

What belongs to other trades: leak tracing, structural drying, mould decontamination, rebuilding work and loss assessment. For each of them, your first point of contact is your insurer: it appoints the assessor and points you to the right companies. Keep the dated photographs and the claim number to hand — every party involved will ask for them.