Yes. Mould can develop when materials remain damp after a leak, although a leak does not mean mould is already present. Stop the water source and dry the area promptly. Plasterboard, timber, carpet and insulation may retain hidden moisture even when the surface looks dry.
What to do immediately
- Stop the water: Close an accessible isolation valve or the property’s main water valve if safe. Have an active, recurring or concealed plumbing leak assessed by a licensed plumber; do not dismantle plumbing or open wall linings yourself.
- Check for hazards: Keep out of areas containing sewage, standing water near electrical equipment, sagging ceilings or structural damage. Do not touch switches or appliances while standing in water. Seek urgent professional help.
- Remove clean water safely: Mop up clean standing water only if there is no electrical, contamination or structural risk. Sewage-contaminated water requires specialist handling.
- Ventilate and dry: Open windows and doors when practical and use a dehumidifier in an electrically safe area. Fans can help with clean-water damage, but do not direct them at visible mould because this may spread particles.
- Assess porous materials: Saturated plasterboard, carpet underlay, insulation and enclosed cavities may need professional drying or replacement. Do not open walls, lift fixed flooring or disturb suspected mould yourself.
There is no fixed timeframe that predicts how quickly mould grows after water damage. Temperature, humidity, airflow, material type and the duration of dampness all affect the risk, so begin drying as soon as possible.
Signs moisture or mould may remain
Look for:
- a persistent musty smell
- spotting, staining or discolouration
- peeling or bubbling paint
- swollen cabinetry or skirting boards
- soft plasterboard, warped timber or lifting flooring
- carpet or underlay that remains damp
- recurring staining or condensation.
Moisture can remain behind shower walls, beneath flooring, under cabinets or within insulation. A dry-looking surface does not rule it out. If the leak was concealed or extensive, or the area remains damp or musty, a water-damage specialist can measure moisture in affected materials.
Appearance and smell cannot identify a mould species or establish a health diagnosis. People with asthma, allergies, weakened immunity or other sensitivities should minimise exposure to damp or mould-affected areas and seek health advice if concerned.
When to get professional help
- Use a licensed plumber for an active, recurring or concealed plumbing leak.
- Use a water-damage restoration specialist to assess retained moisture and dry saturated materials or cavities.
- Use a suitably qualified mould professional if mould is extensive, concealed or keeps returning.
Arrange prompt help if sewage is involved, materials are heavily saturated, or dampness or musty odours persist. For an active or concealed leak, contact our Sydney plumbing team to locate and repair the water source.