A typical scenario (an illustrative example case, not an interview with any resident)

Auntie Daeng has lived in a two-storey townhouse off Pracha Suk Road for decades. The floor of her house sits only slightly above the street, the ground-floor bathroom is next to the kitchen at the back, and a small gully at the front runs into the soi drain.

On the night of the heavy rain, she heard gurgling from the bathroom. When she switched on the light, grey-black water was bubbling out of the floor drain grate, spreading to the bathroom door and into the kitchen. A smell like rotten eggs mixed with toilet filled the whole ground floor. By morning the water had gone down, leaving a thin film of sludge on the tiles, in the grout lines and around the legs of the kitchen cabinet.

She and her daughter scrubbed the floor twice with bathroom cleaner, poured drain cleaner down the pipe and ran fans all day, yet by evening the smell was still there, and stronger once the house was shut for the night. The curtains in the living room and the cushions on the wooden sofa near the kitchen door had picked up the odour. Her four-year-old grandson, who was staying over, had diarrhoea for two days, and the whole family began to worry that germs from the sewage were still in the house.

This can happen in flats, shophouses and townhouses across Din Daeng even when the street only floods ten-odd centimetres, because the problem is not just the depth of water on the road but the pressure of water in the pipes pushing back into the house.

Where Din Daeng Was Waterlogged in 2026, According to News Reports

The points below come from news reports published between late September and early October 2026. Water levels were measured at the time of each report and change constantly.

• Din Daeng Road: 11.4 cm of standing water measured on 26 September 2026 (Thai PBS).
• Ratchadaphisek Road: 10.3 cm on 26 September 2026 (Thai PBS). At 18:30 on 25 September, Ratchadaphisek in front of the Chinese Embassy was listed among Bangkok's waterlogged points (Naewna).
• Pracha Suk Road, Soi Inthamara 34: on 4 October 2026 heavy rain fell in 22 Bangkok districts and this area had about 15 cm of water; on 6 October Pracha Suk Road still had minor waterlogging (Siam Rath).

Across Bangkok, rainfall on 25 and 26 September 2026 exceeded 300 mm in about 48 hours, and rain from 1 to 25 September totalled 487 mm against an average of 269 mm. On 26 September all 50 districts were declared disaster areas, and a DDPM report on 6 October 2026 put the number of affected Bangkok households at 329,000 (Thai PBS, Malay Mail, Bangkok Biz News).

The key point is that Din Daeng was hit by heavy rain several times in less than two weeks. Drains that had not fully emptied after the first storm filled faster the next time, and a home that has had a backflow once is likely to have another unless the cause is fixed.

Drain Backflow Odour Removal in Din Daeng: Why Home Drains Back Up in Heavy Rain

A city home's plumbing connects to the drains in the soi and the street. When heavy rain fills the public drains, the water level in those pipes rises above the lowest drain point in the house, such as the ground-floor bathroom floor drain, the laundry area gully or the channel at the front door. Water simply flows back in, from high to low. Homes whose floors sit below the street, or whose street has been raised over the years, are hit first.

In flats and multi-storey buildings, ground-floor units at the end of a shared stack often back up first, because waste water from the floors above flows down while the outside drain cannot take it.

Where the sewer smell comes from

Sewer smells come from sewage and food waste breaking down without oxygen, producing several gases, best known among them hydrogen sulphide with its rotten-egg smell. Normally each drain has a trap, a U-shaped bend that holds water as a barrier against sewer gas. After a flood that barrier is often broken: sludge clogs it, pressure changes suck the water out, or the house is shut for days and the water evaporates. Sewer gas then flows straight in.

The smell that stays after the backflow stops

A home that took in sewage has two layers of smell. The first is gas still coming from the pipes. The second is the smell already in the house: dried sewage residue in grout, along skirting and on cabinet legs, plus odour soaked into curtains, mattresses, cushions, rugs and wood. Even after the plumbing is fixed, the second layer keeps the smell circulating unless it is dealt with.

Germs in Backflowing Sewage: It Is Not Just About the Smell

Water that rises from drains is sewage, which is far more dangerous than rainwater on the floor. It leaves several kinds of germs behind.

Faecal bacteria

E. coli and Salmonella, found in water contaminated with faeces, cause diarrhoea, stomach cramps, vomiting and fever. They cling to bathroom and kitchen floors, grout and anything the water touched. Young children who crawl or play on the floor and then put their hands in their mouths are most at risk.

Viruses that cause diarrhoea

Norovirus and rotavirus spread through faeces and contaminated water and pass easily within a family. Touching a contaminated surface and then food can make the whole household ill. Respiratory viruses such as influenza and RSV also spread more easily in damp weather when people are shut inside together.

Leptospirosis risk

Drains are home to rats, so water rising from them or standing on the street may carry rat urine, the source of leptospirosis. The bacteria enter through cuts or the eyes, nose and mouth. People who wade through water or clean up sewage without gloves and boots are at risk.

Mold that follows the damp

Once the sewage dries, moisture trapped under cabinets, behind bathroom walls and in absorbent materials feeds mold, which can start growing within 24 to 48 hours. That adds a musty smell on top of the sewer smell and triggers allergies and asthma.

When to see a doctor

See a doctor and mention flood or sewage exposure if you have repeated diarrhoea, vomiting that stops you eating, a high fever, muscle pain especially in the calves, red eyes, low urine output or difficulty breathing. Older people, young children, pregnant women and people with chronic illnesses should not wait.

What Din Daeng Households Face When Drains Back Up and the Smell Stays

Health. People breathing sewer smells every day often get headaches, nausea, poor appetite and broken sleep, while young children and older adults risk diarrhoea from germs left on the floor.

Money. Wooden under-sink cabinets, wooden bathroom doors and ground-floor furniture hit by sewage may swell and hold the smell until they have to be replaced. If mold spreads, repair costs climb.

Time. Many households scrub every day without success because the pipes were not fixed or the odour in materials was never treated.

Business and reputation. Restaurants, cafes and shophouses along Din Daeng and Pracha Suk roads lose customers fast if a sewer smell drifts through the shop. Landlords risk tenants moving out.

Why Pouring Cleaner Down the Drain and Spraying Air Freshener Do Not Work

Drain cleaner or caustic soda. It may dissolve some grease in the pipe, but it does nothing about pressure in the public drains or the smell already in your home. Frequent use of harsh chemicals also damages PVC pipes and is dangerous when mixed with other products.

Scrubbing with bleach alone. Bleach disinfects smooth surfaces you can reach, but not fabric, foam, wood or the air. Its fumes in a stuffy bathroom irritate the airways, and it must never be mixed with toilet cleaners or ammonia.

Air fresheners, deodoriser blocks and incense. They cover the smell for a while, but the source keeps working, so the smell returns as soon as the scent fades.

Stuffing the drain with cloth or a plastic bag. This blocks gas for a short time, but in the next storm the pressure may push water out somewhere else, and the cloth becomes a breeding ground for germs.

Running fans. You should do this, because it reduces moisture, but it does not kill germs in sewage residue or break down odour molecules soaked into materials.

The simple rule is that drain backflow odour must be tackled in two parts together. First, fix the plumbing so gas and sewage cannot come back in. Second, deal with the germs and odour already in the house. Do only one and the smell always returns.

Fix the Plumbing First: What Din Daeng Homes Should Do to Stop Backflow and Smells

• Top up every drain with water, especially bathroom, laundry and balcony floor drains that are rarely used, so each trap holds a water seal.
• Clean grates and traps. Lift the grates, scoop out sludge, hair and debris the water brought in, and rinse with clean water.
• Switch to anti-odour drain grates. Grates with a cover or a one-way flap cut sewer gas when the drain is not in use.
• Ask a plumber about a backflow valve. Homes below street level or with repeated backflows should have the plumbing checked and consider a non-return device.
• Check the plumbing vent. If the vent pipe is blocked, water is easily siphoned out of traps and smells return often.
• Report blocked public drains to the district office. A slow soi drain is a shared cause of backflow for the whole lane.

Once the plumbing is sorted, the next steps are washing away sewage residue, discarding soaked items that cannot be cleaned and drying the house. Only then is it time to deal with the remaining odour and germs with ozone.

Drain Backflow Odour Removal in Din Daeng with WHD Ozone Treatment

Ozone (O3) is a strongly oxidising gas. Released into a sealed room, it reaches every corner, including grout lines, the space under cabinets and the inside of curtains, mattresses and cushions. It breaks down the molecules that cause odours and destroys the cell structures of bacteria, viruses and mold. Afterwards it reverts to oxygen (O2), leaving no chemical residue.

According to test results the company has had certified by Thailand's Department of Medical Sciences and Intertek (UK), the ozone system used by World Health Disinfection (WHD) eliminates viruses, bacteria and mold at 99.99%. The documents are on the certification page.

How the service works

1. Consult by phone or LINE. Describe the house, where the backflow happened and how strong the smell is, and send photos for an initial assessment.
2. Book in advance. The team schedules according to the queue, with no same-day promise.
3. Prepare the house. Carry out basic plumbing fixes, wash away sewage residue, discard soaked items, dry the house, and take all people, pets and plants out. Close doors and windows.
4. Treat zone by zone, for example bathroom, kitchen and ground-floor living room. A typical cycle is about 30 minutes per zone, depending on size and smell.
5. Rest the space while ozone reverts to oxygen.
6. Ventilate and go back in only when the technician says it is safe.

To repeat: ozone treatment is done in a closed space with no people, pets or plants. Ozone deals with the odour and germs left in your home, but it does not repair pipes, does not prevent the next backflow and does not replace washing away sewage or removing soaked materials. If the pipes keep releasing gas every day, the smell will come back, so plumbing must always be fixed alongside. Anyone who is ill should see a doctor.

More service details are on the residential ozone disinfection page, and surface disinfection is covered on the disinfection service page.

10 Reasons to Use Ozone for Drain Backflow Odour Removal in Din Daeng

1. It breaks down sewer odour soaked into materials, rather than just masking it in the air.
2. It reaches grout lines and under cabinets, where sewage residue went but brushes cannot.
3. It reduces germs from sewage, including bacteria and diarrhoea-causing viruses, per the company's certified test results. See the ozone service page.
4. It tackles the mold that follows, cutting the musty smell layered on top of the sewer smell.
5. No chemical residue, which suits kitchens and rooms used by young children.
6. It helps fabrics and cushions such as curtains, mattresses and sofas that picked up the smell but are worth keeping.
7. It is quick, typically about 30 minutes per zone.
8. It suits shops and shophouses. Businesses on Din Daeng and Pracha Suk roads can reopen without a smell bothering customers. Details on the building ozone service.
9. It finishes the job after washing, working where liquids cannot reach.
10. The team is in Bangkok. WHD's office is in Bang Khae, and Din Daeng appointments can be booked in advance by phone or LINE.

Example Case: A Curry-and-Rice Shophouse in Din Daeng

(An illustrative example case to explain the process, not a review from any customer)

Nueng runs a curry-and-rice shop on the ground floor of a shophouse and lives upstairs with his family. After the heavy rain in early October, sewage backed up through the drain in the back kitchen and the bathroom floor drain. He had to close for two days, and when he reopened, regular customers mentioned a strange smell.

He started by calling a plumber to rod the pipes and check the traps, and swapped the floor grates for anti-odour ones. Then he scrubbed the kitchen and bathroom floors, threw out doormats and cardboard boxes soaked in sewage, and ran fans for a full day until everything was dry. He booked the ozone team for his day off. The kitchen, shop front and bathroom were treated one zone at a time while the family went out, and they returned once the technician confirmed ventilation was complete.

The lesson: ozone without fixing the pipes means the smell is back in a few days, and fixing the pipes without treating the smell in the shop means customers still notice it. Doing both is what brings the shop back to normal.

Checklist Before and After Ozone for Homes Hit by Drain Backflow

Before

• Wear rubber gloves, boots and a mask whenever you clean sewage residue, and wash your hands with soap afterwards.
• If sewage reached the sockets, switch off the breaker and have an electrician check before using power.
• Throw away food, utensils that cannot be cleaned and items soaked in sewage, such as rugs, cardboard and mattresses.
• Scrub floors, lower walls and grout with detergent, then rinse with clean water.
• Clean grates and traps, top up every drain and have a plumber check the system if backflow is frequent.
• Dry the house with fans or a dehumidifier.
• Take people, pets and plants out before the appointment.

After

• Return when the technician says so and ventilate as advised.
• Top up rarely used drains once a week so traps do not dry out.
• When heavy rain is forecast, close drain covers and lift items off the floor near drains.
• If the smell returns quickly, the pipes are still releasing gas; have them checked again.
• If anyone has a fever, diarrhoea, calf pain or red eyes, see a doctor.

Health advice after floods: CDC Floods and the Department of Disease Control.

FAQ: Sewer and Drain Backflow Odour Removal in Din Daeng

Q: After ozone, will my drains stop backing up?
A: No. Ozone deals with odour and germs left in the house. Stopping backflow requires plumbing fixes such as working traps, anti-odour grates and a non-return device.

Q: Sewage came in yesterday. Can I treat right away?
A: Wash away the residue and dry the house first. Sewage residue keeps producing smell, and moisture lets mold come back.

Q: How long must I stay out?
A: Typically about 30 minutes per zone, plus rest and ventilation time. The technician will advise the timing for your home.

Q: Can I treat only the bathroom?
A: Yes, but if the smell has reached curtains and cushions in other rooms, those rooms should be treated too. The team will help decide how many zones you need.

Q: I live on the ground floor of a flat with a shared stack. What should I do?
A: Report the shared pipe to the building manager. Inside your unit, wash, dry and maintain the traps, then treat with ozone in a sealed, empty room.

Q: How much does it cost?
A: It depends on area and number of zones. The team assesses and quotes by phone at 065-556-6294 or LINE @whd268. Ozone jobs of 15,000 baht or more come with a free medical-grade disinfectant spray.

Still smelling sewage in your Din Daeng home after a drain backflow? Talk to WHD about an ozone plan.

Phone 065-556-6294 | LINE @whd268 | worldhealthdisinfection@gmail.com
Office in Bang Khae, Bangkok 10160. Appointments by advance booking.

Related Services and References

• Residential and building ozone disinfection
• Ozone cleaning service
• Contact us

References

• Thai PBS: Bangkok road water levels, 26 Sep 2026
• Naewna: Bangkok waterlogged points, 25 Sep 2026
• Siam Rath: heavy rain in 22 districts and Pracha Suk waterlogging, Oct 2026
• Thai PBS: Bangkok rainfall, 25 to 26 Sep 2026
• Malay Mail: all 50 Bangkok districts flood disaster zones, 26 Sep 2026
• Bangkok Biz News: DDPM flood situation, 6 Oct 2026
• CDC: Floods and cleanup safety

Note: water levels and figures in this article are as reported on the dates stated and change daily.