How to get rid of mould after flood or heavy rain

by Josephine Gan    

How to get rid of mould after flood or heavy rain - Andatech Distribution

The recent wet weather in Australia, combined with humidity and high temperatures, have created a breeding ground for mould. In this article, we discuss how to get rid of mould caused by flood or heavy rainfall in your home.

A flood can be one of the most damaging and devastating things to happen to a home. The toll from ex-tropical cyclone Debbie that just tore through New South Wales, Queensland and New Zealand will cause flood woes for years to come.

Aside from the immediate aftereffects caused by water flooding, the aftermath of the water that remains in homes will inadvertently lead to massive mould problems affecting homes, businesses and industries.

Mould is hazardous not just to the property but also to the health of the home’s inhabitants. Mould can trigger asthma-like symptoms including coughing, wheezing and shortness of breath. Some common but lesser known symptoms of mould exposure may also include sleep deprivation, muscle aches, and lethargy.

The good news is there are steps you can follow on how to get rid of mould and protect yourselves from its harmful effects.

Follow the advice below on how to get rid of mould after a flood or heavy rainfall:


Treat the cause of rising damp immediately

Pump out all the water from your property immediately and treat the cause of rising damp as soon as it is detected. Seal any leaks in bathrooms and roofs, overflowing gutters, and blocked vents as soon as you can. While you do that, make sure you have enough ventilation indoors to help reduce moisture before you continue to the next steps.

“Reducing the amount of moisture in a house is the best way to control mould growth. After wet weather conditions, do a thorough clean and open all the doors and windows to dry out the area as quickly as possible,” Adam Trumble, Manager of the National Asthma Council’s Sensitive Choice® Program, said in a media release addressing mould health hazard in Australia.

“If you can, use fans or dehumidifiers to speed up the process,” Mr Trumble added.


Remove affected items immediately and quickly

It is important to remove all items affected by the flood as soon as possible. This is because mould can start to grow within 24 to 48 hours of flooding. That is the expert advice from Dr Cameron L Jones, a PhD level microbiologist with extensive experience in mould assessment and indoor air quality.

“Wet building materials create the perfect conditions for bacterial, yeast and fungal growth,” Dr Jones wrote in his blog post about the effects of flood on health.

Plasterboard and flooring will need to be completely stripped out or demolished if heavily affected by flood. Similarly, wet furnishings and possessions that are unsalvageable must be discarded as well. Doing so is important as these can harbour mould and bacteria that can be harmful to health.

Similarly, the NACA’s mould prevention checklist recommends us to “Be ruthless with the clean out, if possible – hidden damp can cause ongoing problems.”


Clean up as soon as possible

After discarding any items affected by the flood, Dr Jones recommends cleaning up the remaining affected areas with soap and water. Afterwards, use a HEPA vacuum to suck up residual mould and spores throughout the premises.

Be sure to wear protective equipment to protect the lungs and skin. These may include P2/P3 particulate masks, gloves, goggles, and disposable coveralls.

Remove any visible mould by cleaning with naturally fermented white vinegar solution (check out our mould removal infographic for the formula to the mould remover solution).

Dr Jones emphasises the importance of completing remedial works as soon as possible. A study conducted after the 2008 Cedar River flooding looked at bacteria and endotoxin levels in flooded homes. They found microbe levels to be 1.5 to 5.1 times higher in homes undergoing restoration than in those where restoration was complete.


Thoroughly dry your property

“Even after the floodwater has gone, chronic dampness in the walls can still facilitate mould growth,” Dr Jones said.

Therefore, the property still needs to be thoroughly dried to prevent further mould growth.

“This is done using any combination of the central heating system, fans, heaters and dehumidifiers usually in combination with industrial-grade HEPA air scrubbers,” Dr Jones added.

“Home heating will reduce relative humidity, as will dehumidifiers and good ventilation,” NACA’s Mr Trumble said.

Severely flooded homes may take up to months to completely dry out. However, with the right steps, you can ensure that your home is as free from mould as possible.


How to get rid of mould permanently

Dampness and mould can come back if you do not take preventative measures to keep excess moisture out of your home at all times.

As we’ve discussed before in how to kill mould permanently, the most important factor for mould growth is moisture. That’s why it is extremely important that you remove dampness from your home at all times.

A relative humidity (RH) level of 60% indoors and below is good for mould prevention. At this level, there will not be enough moisture in the air for mould to grow. An RH level of 70% and above (for extended periods of time) encourages mould to grow.

How to get rid of mould permanently after the clean up:

  • Kill mould immediately on sight
  • Treat all leak problems immediately
  • Ensure downspouts and gutters are clean
  • Vent clothes dryers, bathroom exhaust fans and kitchen exhaust fans outdoors
  • Ensure proper ventilation indoors (open doors and windows when possible)
  • Remove indoor pot plants (which promote mould growth)
  • Avoid the use of organic mulches and compost heaps

If you are concerned, you can purchase a hygrometer to continuously monitor the humidity levels in your home. If humidity is a persistent problem in your home, then a dehumidifier is your best bet against removing damp completely and getting rid of mould.

A dehumidifier is helpful in homes with severe humidity issues, or in older, less ventilated buildings. They’re also commonly used in basements, since underground areas rarely get good ventilation. Dehumidifiers are also helpful in bathrooms without windows, or in specific areas of the home that require moisture removal.


We hope you’ve found this article on how to get rid of mould after a flood or heavy rainfall useful. If you have any tips of your own, do share it with us in the comments section below.

Disclaimer: The information provided in this article is for general reference only. Please seek advice from professionals according to your needs.

Josephine Gan

As our Customer Service Manager, Josephine has a great understanding of people- which is not surprising, given that her major is in Psychology. She is able to transfer her friendly demeanour into our safety and support related posts for our products and services.