Key takeaways (30-second read)

• How to clean a house after a flood starts with safety: switch off the power, check for gas and wear protective gear before you go in.
• The order is: photograph the damage, take wet items out, shovel out mud, wash from top to bottom, dry the house, then disinfect.
• Wash away dirt with clean water and detergent before using any disinfectant, and never mix cleaning products.
• Finish with whole-house disinfection fogging and ozone treatment for mold and musty odors, with no people or pets inside during ozone.
• Do not rush to repaint or seal walls. Let them dry completely and keep watching for mold for several weeks.

Table of contents

1. A story from the field: a riverside home on the Pa Sak after the flood
2. Before you start: safety and equipment
3. 10 steps to clean a house after a flood
4. Room by room: kitchen, bathroom, bedrooms and walls
5. Mistakes that bring musty odors and mold back
6. Comparison table: doing it yourself vs. professional help
7. Disinfection and ozone treatment in Ayutthaya with WHD
8. Before and after, plus a homeowner's voice
9. FAQ: cleaning a house after a flood

A story from the field: cleaning a house after a flood on the Pa Sak River

Somsri is sixty-three. She lives in a two-storey house, half concrete and half wood, on the bank of the Pa Sak River on Ayutthaya's old city island. The house has been through floods before, but in 2026 the water rose almost a meter inside and stayed for nearly two weeks. Somsri moved to a temporary shelter with her granddaughter.

When she came back, the lower door had swollen so badly it barely opened. A layer of mud almost a hand's width deep covered the ground floor. The wooden kitchen cabinet had toppled over, the refrigerator smelled of rotting food, the wooden walls downstairs carried a clear tide line, and the whole house smelled of mud and drains so strongly that she had to open every door and window.

Her son drove up from Bangkok to help over the weekend. The two of them stood looking at the house for a long time, unsure where to begin. Should they shovel the mud first or carry things out? Which cleaning products should they use? What should they be careful about, especially the power sockets that had been underwater?

Her son searched for "how to clean a house after a flood" and wrote the steps down as a list, so the work would have an order and nothing would need to be done twice. This article is that same kind of list, put together by the World Health Disinfection (WHD) team from experience in flooded homes.

Somsri's situation is shared by many families in Ayutthaya, from Bang Pa-in to Bang Ban and Sena. Older homes, wooden structures and long flood durations make the cleanup harder here than in many other places. A clear plan makes a real difference to how quickly and safely families can move back in.

Before you clean a house after a flood: safety and equipment

Before you start washing, make sure the house is safe enough to work in. The dangers after a flood are not only germs.

Electricity and gas

Switch off the power at the main breaker before entering. Do not plug in or switch on any appliance that has been underwater. Have an electrician inspect the system before the power is restored. If you smell gas, leave the house immediately and call a qualified technician.

Structure and dangerous animals

Look for cracks, sagging floors and doors or windows that have warped out of shape. Wooden houses that soaked for a long time may have weakened floorboards, so walk carefully. Watch out for snakes, centipedes and other animals that may have sheltered inside to escape the water.

Personal protective equipment

• Rubber boots, thick rubber gloves and splash-proof glasses.
• A fine-particle mask, especially when dealing with mold.
• Long sleeves and long trousers to reduce contact with mud and dirty water.

Anyone with cuts should cover them completely, because floodwater and mud increase the risk of leptospirosis. Follow guidance from Thailand's Department of Disease Control, and see a doctor promptly if you develop a fever or muscle pain. This article is not medical advice.

Cleaning equipment

Shovels, brooms, floor squeegees, buckets, scrubbing brushes, cloths, heavy-duty garbage bags, detergent or general-purpose cleaner, and fans or a dehumidifier for the drying stage.

Plan your helpers and your days

Cleaning a flooded house is physically hard. Decide who will do the heavy lifting, who will sort belongings, and who will keep older family members and children away from the dirtiest work. Take breaks, drink clean water, and wash your hands well with soap before eating or drinking anything.

10 steps: how to clean a house after a flood

Follow this order so you do not have to clean twice, and so mold has less chance to come back.

1. Photograph all the damage. Capture every room, the waterline on the walls and damaged items, for insurance claims or assistance applications.
2. Open every door and window. Let air flow and start removing humidity from the very first hour.
3. Take wet items out of the house. Sort them into three piles: salvageable, to discard and to assess later, such as mattresses, rugs and fabric sofas.
4. Throw away food and medicine that got wet. Include food from a refrigerator that lost power for a long time, to avoid food poisoning.
5. Shovel out mud while it is still damp. Wet mud is much easier to remove than mud that has dried hard. Use shovels and squeegees to push it out of the house.
6. Wash from top to bottom. Clean walls from above the waterline downward with clean water and detergent, then wash the floor last.
7. Rinse with clean water. This removes soap and leftover mud that would otherwise weaken any disinfectant.
8. Dry the house. Run fans or a dehumidifier, pull furniture away from the walls and open every cupboard and drawer.
9. Disinfect surfaces. Wipe high-touch points with CHEMGENE HLD4H spray, and consider our whole-house disinfection service for hidden corners you cannot reach.
10. Deal with musty odors and mold. Use our ozone treatment service once the house is dry, then keep checking walls and corners for several weeks.

How many days will it take?

Most homes need several days to get through steps 1 to 8, and concrete walls may need several weeks to dry completely. Do not rush the drying stage. It is the step that decides whether mold comes back.

Keep a simple log

Write down what you did each day, which rooms are finished and which items you discarded. It helps when several family members share the work over different weekends, and it is useful for insurance or assistance claims later. A few lines a day are enough.

How to clean a house after a flood, room by room

Kitchen

Throw away food, condiments, and wooden or plastic utensils that soaked in floodwater. Wash metal pots, plates and bowls with dish soap, rinse them in hot water and let them air-dry. Wooden kitchen cabinets that have swollen or grown mold inside should be considered for replacement, and the refrigerator should be checked by a technician before it is plugged in.

Bathroom

Flush the toilet and drains with water and check that drainage is not blocked. Scrub tiled walls and grout with a brush. If drain smells come back up, you may need a plumber to inspect the pipes and septic tank.

Bedrooms and living room

Mattresses, pillows, rugs and fabric sofas that soaked in floodwater for a long time usually need to be discarded. Curtains and bed linen that can be washed should go through the hottest wash the fabric allows and be dried in the sun. Solid wood furniture should be wiped, aired and checked for mold on the legs and back panels.

Concrete and wooden walls

Wash concrete walls and give them time to dry, without painting yet. For wooden walls and floors, which are common in traditional Ayutthaya houses, open up the space under the house so air can pass, and wipe off mud. If you find rotten or springy wood, ask a carpenter to assess it first.

Appliances and electrical systems

Do not switch on any appliance that has been underwater until a technician has checked it. Sockets and switches below the waterline should be replaced or checked by an electrician before power is restored to the whole house.

Documents, photos and keepsakes

Wet documents and family photos are often the hardest losses. Separate them gently, lay them flat in a shaded, airy place, and avoid rubbing them. Important papers such as land deeds or house registration documents can usually be reissued, so ask the relevant office before throwing anything away. Valuable or irreplaceable items may need a conservation specialist rather than household cleaning.

Outdoor areas and the space under the house

Mud and debris left under a raised house or in the yard keep releasing smells and moisture. Clear them away, fill or drain any standing water, and remember that pools of water left after the flood quickly become mosquito breeding sites.

Mistakes when cleaning a house after a flood that bring musty odors and mold back

Using disinfectant before washing off the mud

Disinfectants work poorly on surfaces still covered in mud and grime. Always wash dirt away first.

Mixing several products in one bucket

Mixing bleach with certain bathroom cleaners can release dangerous gases. Use one product at a time, following the label, with good ventilation.

Locking the house as soon as the washing is done

Many families finish washing, lock up and go back to where they are staying. The moisture gets trapped inside, and mold grows very quickly within days.

Painting or wallpapering too soon

Walls that are still damp make new paint bubble and allow mold to grow underneath it, which means stripping everything and paying twice.

Covering smells with fragrance

Fragrance only helps for a short time. The real cause is moisture and remaining germs, which need drying, disinfection and ozone treatment to resolve.

Using a pressure washer on everything

A pressure washer is useful on outdoor concrete, but indoors it can force water deeper into walls, wooden joints and electrical boxes, making drying much slower. Use buckets, brushes and squeegees inside the house.

Forgetting hidden spaces

The cavity under the stairs, the gap behind built-in cabinets, the false ceiling and the space under a raised wooden floor are where moisture and smells linger longest. If you only clean what you can see, the musty smell will keep coming back from these spots.

Comparison table: cleaning a house after a flood yourself vs. professional help

Splitting the work this way lets homeowners save money on the parts they can do themselves, and use professionals for the steps that need specialist equipment and safety know-how.

A practical approach many Ayutthaya families use is to spend the first weekend on safety, sorting and mud removal with relatives and neighbors, the following days on washing and drying, and then book professional disinfection and ozone treatment once the house is dry. This keeps costs under control while making sure the final, most technical steps are done properly.

Post-flood disinfection and home ozone treatment in Ayutthaya with WHD: 10 reasons homeowners choose us

Once homeowners have finished steps 1 to 8, the WHD team steps in for the parts that need specialist equipment: whole-house disinfection fogging and ozone treatment.

1. We survey the house first and tell you honestly whether it is dry enough for the next step.
2. We use CHEMGENE HLD4H disinfectant and can show you the label.
3. Our fine-mist fogging reaches hidden corners, the space under stairs and behind cabinets.
4. We use an ozone generator with controllable timing.
5. We look after wooden and traditional Thai houses by opening the underfloor space and placing equipment carefully.
6. We control the ozone dose and cover or remove electronics first.
7. We explain safety steps clearly: no people, pets or plants inside during ozone treatment.
8. We offer dust mite removal for mattresses and sofas that can be kept.
9. We offer mosquito spraying around the house, since standing water is common after floods.
10. You can reach us by phone, LINE and email, including after the job is done.

What to expect on the day

The team arrives, walks through the house with you, and agrees which rooms will be treated and which items need to be removed or covered. Everyone, including pets, leaves the house. The team fogs with disinfectant, then seals the house and runs the ozone treatment. After the ventilation period, the team checks the result with you and explains what to watch over the following weeks.

Safety during ozone treatment

During ozone treatment there must be no people, pets or plants in the house. Afterwards, open doors and windows for the ventilation time the team sets before going back in. Rubber, electronics and delicate artworks should be covered or removed first. Read more about residential ozone disinfection on our website.

Before and after cleaning a house after a flood, plus a homeowner's voice

FAQ: how to clean a house after a flood

Where should I start cleaning a house after a flood?

Start with safety: switch off the power, check for gas smells and put on protective gear. Then photograph the damage, open doors and windows, take wet items out, and only then shovel out mud and wash from top to bottom. Following this order saves you from cleaning the same areas several times.

What should I use to wash a house after a flood?

First use clean water with detergent or a general cleaner to remove mud, then rinse with clean water. After that, use a disinfectant according to its label, such as CHEMGENE HLD4H on high-touch surfaces. Never mix different cleaning products together.

How many days after a flood should I disinfect and ozone-treat the house?

Do it after the mud is out, the house has been washed and it has started to dry, because disinfectants and ozone work best on clean surfaces that are not soaking wet. Timing depends on the size of the house and how deep the flood was, and the team can help assess readiness.

How long should concrete walls dry before painting?

Concrete walls that soaked for a long time may need several weeks to dry fully, depending on their thickness and ventilation. Wait until there are no damp patches or musty smells, and talk to a painter before repainting, so the new paint does not bubble or hide mold underneath.

Can I still use appliances that were underwater?

Do not plug them in or switch them on until a technician has inspected them. Some appliances can be repaired, but others may be unsafe even if they look fine. Electrical safety must always come first after a flood.

Is ozone treatment safe for wooden houses in Ayutthaya?

Yes, when done correctly. The team controls the dose and duration and chooses suitable machine positions for wooden structures. Nobody, no pets and no plants should be inside during treatment, and the house must be ventilated before anyone returns.

Do you offer post-flood disinfection in Ayutthaya?

Yes. WHD works across Phra Nakhon Si Ayutthaya, including the old city island, Bang Pa-in, Bang Ban, Sena and nearby areas. Call 065-556-6294 or message LINE @whd268 with photos of your house after the mud has been cleared, so the team can assess it and book a visit.

Finished washing, but the musty smell and mold are still there?

Let the WHD team handle whole-house disinfection and ozone treatment to complete your home's recovery.

See our disinfection service

Book ozone treatment

Call 065-556-6294 · LINE @whd268 · worldhealthdisinfection@gmail.com

Further reading and sources

• Whole-house post-flood disinfection service
• Ozone treatment for mold and musty odors
• Ozone deodorizing for odors and chemical residue
• Mosquito spraying after floodwater recedes
• All our flood recovery articles
• World Health Organization: floods and health
• Thailand Department of Health: environmental health after floods