A typical scenario (example case, not a real person)

Tom has run a small coffee shop in a two-unit shophouse on the Pak Kret stretch of Chaeng Watthana Road for five years. That night she sat in her nearby condo watching the shop's security camera on her phone. At around 3 a.m. she saw water slide under the rolling steel shutter. By 6 a.m. it was knee-high inside. The fabric sofa, the cake chiller and the sacks of coffee beans stacked on low pallets were all under water. She could not even get to the door: the road outside was close to waist-deep and two sedans sat drowned in front of the shop.

Two days later the water drained away. She and her staff threw out what was ruined, hosed the floor, wiped the walls with bleach and left fans running overnight. On the third morning she rolled up the shutter and the smell that came out was not coffee. It was drain and damp laundry, and it would not leave. A neat line of tiny black dots had started to appear on the gypsum wall behind the counter at exactly the height the water had reached. One regular walked in, paused, and walked straight out again. That is the situation many owners and residents along Chaeng Watthana found themselves in after that night, and it is why this article exists.

Where Chaeng Watthana Road Flooded: What Happened

The facts in this section come only from Daily News reporting on 26 September 2026. We have not added numbers that do not have a source, and water conditions change every day, so please follow announcements from Nonthaburi Province and local authorities as well.

• Heavy rain all night left water nearly 1 metre deep on Chaeng Watthana Road.
• Small vehicles were banned from passing because the depth was unsafe for sedans and motorcycles.
• The Chaeng Watthana expressway exit and the Muang Thong Thani exit were closed to stop traffic coming down into deep water.
• Several cars and motorcycles were submerged and damaged, both parked ones and those that tried to push through.
• Nonthaburi declared a disaster zone covering Mueang Nonthaburi District and Pak Kret District.

For national context, the Department of Disaster Prevention and Mitigation (DDPM) reported on 2 October 2026 that flooding affected 31 provinces plus Bangkok, a total of 1,245,581 households and 3,535,206 people, caused by heavy to very heavy rain combined with runoff from the north. These are figures as of the report date and may change the next day.

What makes the Chaeng Watthana flood different from a flooded housing estate or a riverside village is that this was a flooded arterial road. It runs past commercial buildings, condominiums, offices, showrooms, restaurants and car parks. Water flowing along a main road is not clean rainwater. It picks up engine oil, tyre dust, street grime, litter and the overflow from storm drains and sewer chambers, and then it pushes into the ground floors on both sides of the road.

What Road Floodwater Carries Into Buildings: Every Kind of Flood Germ

Urban road floodwater is a mix of rain, storm-drain water and sewage from overflowing septic tanks and manholes. Inside a building it leaves several groups of organisms at once, and each reaches the body by a different route.

1) Bacteria from sewage and drains

The usual suspects are E. coli, which comes from human and animal faeces, and Salmonella, best known for food poisoning. They cling to floors, table legs, counters and anything that went under. If cleaning misses a spot and a hand touches it before touching food, the result can be diarrhoea, stomach cramps, nausea and vomiting. Restaurants and cafes on Chaeng Watthana need to be especially careful because nearly all of their food preparation happens on the ground floor.

2) Leptospirosis risk

A busy road lined with food outlets and bins usually has rats living in the drains. When the drains overflow, rat urine carrying Leptospira mixes into the water. Anyone who waded along Chaeng Watthana to check on a car or open a shop, especially with a cut on the foot or leg, could pick it up through the skin. Watch for sudden high fever, headache and marked pain in the calf muscles, usually within one to two weeks after wading. Anyone with these symptoms must see a doctor and mention the floodwater. Ozone treatment of a building is not a medical treatment and never replaces a hospital visit.

3) Viruses on surfaces and in damp, stale air

Norovirus and rotavirus cause diarrhoea and vomiting, particularly in small children. RSV and influenza spread more easily when many people crowd into closed spaces, such as condo residents helping each other carry things out of a lobby or office staff returning to a room that has only just drained. High humidity and poor ventilation make it easier for respiratory germs to pass from person to person.

4) Mold that starts within 24 to 48 hours

The WHO and the US CDC both advise cleaning and drying within 24 to 48 hours after the water leaves to limit mold. Many buildings on Chaeng Watthana use gypsum partition walls, ground-floor suspended ceilings, office carpet and plywood furniture. All of these soak up water and dry slowly. Mold in these materials releases spores into the air, which can trigger allergies, asthma and chronic lung conditions.

5) Musty and sewage odour

The smell that lingers comes from two sources: the breakdown of organic matter and sewage that soaked into materials, and the musty by-products of mold and bacteria still living in walls and fabrics. Odour is not just unpleasant. For a shop, restaurant, clinic or office that receives customers, it is the first signal telling people the place is not yet safe.

Who Is Most at Risk in Buildings Along Chaeng Watthana

• Older people living in ground-floor shophouse or townhouse rooms, who have weaker immunity and often refuse to move out during cleanup.
• Small children who crawl on floors and put things in their mouths, and so face more diarrhoea risk from rotavirus and norovirus.
• Pregnant women, who should avoid wading and avoid rooms with visible mold.
• People with chronic illness such as diabetes, kidney or heart disease, or anyone on immune-suppressing medicine.
• Restaurant staff and cleaners who handle flooded floors and equipment directly.
• Car owners who waded out to their vehicles, often picking up scrapes from climbing or from sharp objects hidden in the water.

The Real Cost of the Chaeng Watthana Flood: More Than Drowned Cars

Health: Diarrhoea, itchy rashes, lingering coughs and allergy flare-ups tend to appear in the first week after people move back in. Many assume it is an ordinary cold when the real source is mold inside the walls.

Money: Owners along the road face car repairs, new furniture, replacement electrical equipment and lost trading days. If recovery is done in the wrong order, mold comes back and walls must be stripped a second time, which costs far more than doing it right once.

Time: Chaeng Watthana is a daily commuting route. With the expressway exits closed, journeys stretched and there was less time left for cleaning, so many households cut corners by wiping and shutting the door.

Reputation: For restaurants, clinics, tutoring schools and showrooms on the road, customers remember a smell for a long time. One review that mentions a musty odour can send a new customer somewhere else.

Family: Many families live upstairs and trade downstairs in the same shophouse. They live with the damp and the smell around the clock, on top of the stress of damaged property and worry about their children's health.

Each Building Type on Chaeng Watthana Has Its Own Weak Spots

The Pak Kret section of Chaeng Watthana packs very different buildings side by side, so there is no single recipe for recovery.

Shophouses and commercial units: The ground floor is usually a shop with a rolling shutter that cannot keep water out. Water enters under the shutter and back up through the rear drain. Weak spots are porous masonry walls, the back toilet, and the storage cupboard under the stairs, which is a closed space with no airflow.

Condominiums: Upper units may stay dry, but the lobby, mailroom, gym, meeting rooms and ground-level or basement parking are shared by everyone. If mold takes hold in the lobby or the central air-conditioning, the smell travels through the whole building. Juristic persons should plan common-area recovery as a structured project.

Offices and showrooms: Carpet, ceilings, partition walls and under-floor cabling all hold moisture. Ground-floor server rooms and document stores need special attention, because paper that got wet and never fully dried is an ideal home for mold.

Townhouses and homes in side lanes: Lanes that sit lower than the main road receive the water draining off it. These homes can stay flooded longer than the road itself, so materials soak longer and mold goes deeper.

Why the Usual Quick Fixes Are Not Enough

Bleach alone: Bleach works on smooth, non-porous surfaces. On gypsum, plywood or porous concrete it does not reach the mold rooted inside, and the water in the solution adds even more moisture. Mixing bleach with ammonia or some toilet cleaners can also release dangerous gas.

Fans alone: Fans dry the surface, but in storerooms and dead corners where air does not move, moisture stays. Fans also blow mold spores around the room.

Air freshener or scented candles: Fragrance hides the smell for a while. The source is still there, and the odour returns as soon as the scent fades.

Painting over mold: This is the most expensive mistake. Mold under the paint pushes it into blisters that peel within weeks, and the whole wall has to be redone.

Closing the room to let it dry by itself: In Nonthaburi's humid late rainy season, a sealed room does not dry. It becomes a large mold incubator.

The Right Recovery Order for Buildings After the Chaeng Watthana Flood

Ozone is a final step, not a first step, and it never replaces washing or drying. The recommended order is:

1. Safety first: switch off ground-floor power before entering and have an electrician check the system before it is used again. Wear boots, rubber gloves and a mask.
2. Photograph the damage: for insurance claims and assistance. Because Pak Kret is inside the declared disaster zone, ask the Pak Kret District Office or your local administration about available support.
3. Remove mud and ruined items: carpets, mattresses, fabric sofas and other soaked materials usually need to go.
4. Wash with clean water and detergent: floors, walls, counters and any furniture you are keeping, then disinfect surfaces as recommended.
5. Strip waterlogged materials: gypsum boards, insulation and swollen ceiling panels should be cut out above the water line.
6. Dry properly: open doors and windows, run extraction fans and dehumidifiers until materials are dry inside and out.
7. Ozone to remove remaining germs and odour: once the space is clean and dry, ozone deals with the germs, mold and smells hiding in the air and in gaps no cloth can reach.
8. Ventilate and monitor: after treatment, ventilate for the time the team specifies, then keep an eye on smells and walls over the following weeks.

How WHD Ozone Disinfection Works for Chaeng Watthana and Pak Kret

World Health Disinfection (WHD) is a disinfection company based in Bang Khae, Bangkok. We do not have a branch in Pak Kret, but we can plan service for customers along Chaeng Watthana Road, with the appointment and travel confirmed by phone or LINE first. We do not promise same-day arrival, because demand after floods is high.

How ozone works: Ozone (O3) is a molecule of three oxygen atoms with strong oxidising power. Released into a sealed room, it spreads through the whole space, including corners a cloth or brush cannot reach, and breaks down the cell structures of viruses, bacteria and mold as well as odour molecules. It then reverts to ordinary oxygen (O2), leaving no chemical residue on surfaces. According to the test results certified for the company by Thailand's Department of Medical Sciences and Intertek (UK), ozone treatment eliminates viruses, bacteria and mold by 99.99%.

The process:

1. Talk to us by phone or LINE and send photos, room sizes and the height the water reached.
2. Book a date. The team inspects, divides the area into zones and checks that rooms are clean and dry enough.
3. Prepare the room, close doors and windows, and make sure all people, pets and plants are out.
4. Fill the zone with ozone to the target concentration and hold it for the contact time. A typical cycle is about 30 minutes per zone.
5. Switch off, rest the room and ventilate before anyone is allowed back in.

Safety rule: ozone treatment is done only in an empty, closed room. No people, pets or plants may be inside during treatment, and no one re-enters until the rest and ventilation period is over. For condos and multi-unit buildings, the team plans with the juristic person to close areas and notify residents in advance.

The service covers homes, condos, hotels, offices, factories, schools and hospitals. See the residential and building ozone disinfection service page for details.

10 Reasons Shops, Condos and Offices on Chaeng Watthana Should Use Ozone After the Water Recedes

1. It reaches where hands cannot: ozone gas gets behind cabinets, under counters and into the void above ceilings.
2. It tackles drain and musty odour at the source rather than masking it, which matters for roadside restaurants and cafes.
3. No residue: ozone reverts to oxygen, which suits food preparation areas.
4. Several germ groups in one treatment: bacteria, viruses and mold, according to the company's certified test results.
5. Good for condo common areas such as lobbies, mailrooms and gyms that many people share.
6. Short cycle per zone: about 30 minutes per zone, which helps owners plan a reopening date.
7. Less chance of stripping walls twice: done after proper drying, it lowers the chance of mold returning in the same spot.
8. Protects vulnerable family members such as grandparents, toddlers and allergy sufferers living above the shop.
9. Builds confidence for customers and staff when you can say the premises have had post-flood ozone disinfection.
10. Free medical-grade disinfectant spray with any ozone job of 15,000 baht or more, under the company's current promotion.

Before and After: A Chaeng Watthana Shop That Followed Every Step

Example Case: A Condo Lobby on Chaeng Watthana

(An example case to explain the process, not a verified customer review)

Ek manages the juristic person of a condominium on the Pak Kret side of Chaeng Watthana. On the night of the heavy rain, water came into the lobby, the mailroom and the ground-floor gym, and several residents' cars were swamped in the ground-level car park. Once the water went down, residents complained that they met a musty smell every morning as they stepped out of the lift, and some said their young children had started coughing as they passed through the lobby.

First, the housekeeping team removed the lobby carpet and sofas. Contractors cut the gym's partition walls out above the water line, washed every floor and wall, and ran dehumidifiers for several days until the materials were dry. The juristic person then contacted WHD on LINE with a floor plan and photos. The team suggested three zones: lobby and mailroom, gym, and the common storeroom. Residents were told in advance that the ground floor would be closed for a short time, and an alternative entrance was arranged.

On the day, the team closed one zone at a time, checked that no people or pets were inside, ran the ozone cycle, then rested and ventilated the zone before moving to the next. The musty smell in the lobby fell noticeably afterwards. The juristic person kept the dehumidifiers running for a while longer and advised residents whose children were still coughing to see a doctor, because ozone deals with germs in the building, not with illness in people.

Checklist Before and After Ozone for Buildings on Chaeng Watthana

Before ozone

• An electrician has checked sockets, switches and the ground-floor board.
• All mud, rubbish, carpets and soaked fabric furniture are out.
• Floors, walls and counters are washed with clean water and detergent.
• Swollen, waterlogged partitions and ceilings are removed.
• The space is dried with extraction fans and dehumidifiers until materials are truly dry.
• Food, medicine and personal items you do not want exposed are taken out.
• All people, pets and plants have left the area.

After ozone

• Wait until the rest and ventilation period the team gives you is over before going back in.
• Open doors and windows to let air move.
• Watch walls and corners for one to two weeks. If new mold appears, look for hidden moisture.
• Clean food-contact surfaces again before using them.
• Anyone with fever, calf pain, diarrhoea or a rash should see a doctor.

FAQ: Ozone After the Chaeng Watthana Flood

Does WHD have a branch in Pak Kret?
No. WHD is based in Bang Khae, Bangkok. Customers around Chaeng Watthana Road can plan service by phone on 065-556-6294 or LINE @whd268, and the team will confirm the date and travel.

Can ozone replace cleaning?
No. Mud removal, washing and drying always come first. Ozone is the final step to deal with remaining germs and odour.

Can I stay in the room during treatment?
No. The room must be empty of people, pets and plants, and you wait until the rest and ventilation period is over before going back in.

Can a condo treat both common areas and units?
Yes, with planning alongside the juristic person: zoning, closing areas and notifying residents in advance.

How long does it take?
A typical cycle is about 30 minutes per zone, not counting preparation and ventilation time. The number of zones depends on floor area.

I waded along Chaeng Watthana to check my car and now have a fever and calf pain. What should I do?
See a doctor promptly and mention the floodwater. These can be signs of leptospirosis, which needs medical treatment. See the CDC flood guidance for more.

Is there a promotion?
Ozone jobs of 15,000 baht or more come with a free medical-grade disinfectant spray.

Ready to Bring Your Chaeng Watthana Building Back?

Send photos of the space and the water line to the WHD team, and we will help plan ozone treatment once your rooms are clean and dry.

See the Ozone Disinfection Service

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

Related Links and References

WHD services

• Residential and Building Ozone Disinfection
• Disinfection Service
• Contact Us

References

• Daily News (26 Sep 2026): Chaeng Watthana Road flooded nearly 1 m, expressway exits closed
• Bangkok Biz News: DDPM flood situation report
• Khaosod English (29 Sep 2026): More than 2.6 million people affected by floods
• CDC: Floods and cleanup
• WHO fact sheets