A typical scenario: the dormitory where a whole floor got pink eye

In Hat Yai, Songkhla, Nui owns a three-storey, twenty-room student dormitory near the university. The ground floor holds the shared bathrooms, a laundry room and six more bedrooms. After days of torrential rain the city flooded, and the ground floor sat under almost waist-deep water for four days. Some students went home; others squeezed in with friends upstairs and waded down every day to use the one shared bathroom that still worked.

When the water receded, Nui hired workers to hose out the mud and scrub the bathroom floors with toilet cleaner, then let students move back in within three days because she was afraid of losing tenants. The bathrooms looked cleaner, but they still smelled damp. Small black spots speckled the tile grout. The bath mats that had soaked for days were dried in the sun and put back in place, and the shower curtains still had brown stains along the hem.

A week later, two male students who had waded through water every day found the skin between their toes had turned white and soggy, and itched so much they could not sleep. One scratched until the area became red, swollen and filled with pus, and he had to visit a clinic. A few days after that, a female student on the second floor developed red, watering eyes with sticky discharge in the morning, and her roommate soon followed. Within a week, five students had pink eye. Nui herself was caring for her 69-year-old mother, who has diabetes, and noticed that a small scrape on the top of her mother's foot, picked up while carrying belongings away from the water, had turned red, hot and painful.

The dormitory's LINE group started filling with messages asking, "Are our bathrooms actually clean?" Some parents phoned, and two students asked to move out. Nui realised that a bathroom that looks clean is not necessarily free of germs. This article explains which organisms are behind skin disease, flood foot and pink eye after floods, why the bathroom sits at the centre of the problem, and how to fix it systematically.

This story is an illustrative scenario based on situations commonly seen after floods, not an account of a specific customer.

Three groups of germs behind post-flood skin problems

Skin and eye conditions are among the most common health problems after a flood. Thailand's Department of Disease Control warns about flood foot, pink eye and skin rashes every time there is serious flooding. The root causes are skin that has been soaked for too long and germs that thrive in wet conditions, and a bathroom after a flood offers them everything they need.

1. Staphylococcus aureus: the germ already on us, waiting for broken skin

Staphylococcus aureus lives harmlessly on the skin and in the nose of many people. But when skin becomes soggy, cracked, scratched or wounded, it gets in and causes infections such as impetigo, boils, folliculitis and even cellulitis, with swelling, redness, heat and pain in the tissue under the skin. It spreads by direct contact and through shared items such as towels, razors and bath mats, and it can survive for a time on fabrics and surfaces, especially in damp places.

2. Pseudomonas aeruginosa: the water-loving bacterium

Pseudomonas aeruginosa thrives in water and soil. It likes to form slimy biofilms inside drains, shower heads, tap aerators, sponges and scrubbing brushes that never dry out. It can cause itchy red bumps of folliculitis after contact with contaminated water, wound infections that sometimes produce blue-green pus with a distinctive smell, and eye infections, particularly in contact lens wearers who rinse lenses or cases in tap water or unclean water. A corneal infection from this organism can be severe enough to threaten eyesight.

3. Bathroom mould and skin fungi

A post-flood bathroom is home to two kinds of fungus. The first is mould on walls, grout, silicone sealant, ceiling boards and curtains, which releases spores into the air and aggravates allergies, asthma and sinus problems. The second is skin fungi, such as those that cause athlete's foot and ringworm, which spread via wet floors, bath mats, shared flip-flops and towels.

How flood foot develops

Flood foot, which Thais call "nam kat thao" or "water-bitten feet", is not caused by a single germ; it is a process with several stages. First, skin soaked in dirty water for long periods turns white, wrinkled, peeling and itchy. This is irritation from water and dirt. Second, if the skin stays damp, fungi move into the spaces between the toes, causing scaling, cracking and odour. Third, if scratching opens the skin, bacteria such as Staphylococcus or Pseudomonas pile on, producing red, swollen, hot, pus-filled wounds that need a doctor.

How pink eye spreads after a flood

Conjunctivitis after floods can be caused by viruses or bacteria. It spreads very easily when hands touch an infected person's tears or discharge and then rub one's own eyes, and through handkerchiefs, towels, pillowcases and shared surfaces such as bathroom door handles, taps and towel rails. Washing the face with floodwater or unclean water increases the risk directly. Symptoms include red, gritty eyes, watering, discharge and swollen eyelids.

Who is at risk, and when to see a doctor

People with diabetes are at the highest risk, because foot wounds heal slowly and can spread without much pain if nerves are damaged. Older adults with thin skin, young children who rub their eyes and play in water, pregnant women, people with weak immunity or chronic skin conditions, and contact lens wearers all need extra care. See a doctor immediately if a wound becomes red and swollen quickly, produces pus or comes with fever, or if there is severe eye pain, blurred vision, sensitivity to light, or one very red and painful eye. Anyone who waded through floodwater and develops high fever with calf pain, or red eyes with fever, should also tell the doctor about possible leptospirosis.

The impact goes well beyond an itch

Health

An infected foot wound in someone with diabetes can escalate to a hospital stay. Pink eye complicated by secondary infection or corneal inflammation can affect vision. And sleepless nights from constant itching weaken the immune system just when the body most needs to recover.

Money

There are medicines and doctor's fees, plus replacing bath mats, shower curtains and towels. For owners of dormitories, apartments or homestays, losing even two or three tenants means several months of lost income.

Time

Students miss classes, and workers take sick leave because pink eye is so contagious, while owners clean the same rooms again and again without knowing where the problem really comes from.

Reputation and family

In an age when everything is discussed in chat groups and online reviews, a message saying "the bathrooms in this dorm gave me pink eye" does damage fast. At home, caring for an older parent with an infected wound while several children have red eyes adds up to relentless stress for everyone.

Why scrubbing the bathroom does not end the problem

Most people think the bathroom is the easiest room to clean. After a flood it becomes the most complicated one, because standing water, pipes, grout and several kinds of fabric all come together in one small space. These are the mistakes we see most often.

1. Scrubbing the floor but not the drains and shower. Pseudomonas biofilm clings inside drain holes, odour traps, shower heads and bidet hoses. Scrubbing the tiles alone never reaches these reservoirs.
2. Painting bleach onto black grout. The black may fade until it looks gone, but mould threads buried deep in porous grout and silicone survive, and the spots soon return.
3. Sun-drying mats and curtains and using them again. Bath mats and shower curtains that sat in floodwater for days can still hold germs and grime in their fibres even after drying in the sun.
4. Keeping the bathroom shut. In a windowless bathroom, or one whose extractor fan was ruined by the flood, humidity lingers all day, so mould and bacteria keep growing.
5. Relying on deodorising sprays and blocks. The musty smell is masked, so the room feels clean, while the source remains. Some fragrances also irritate the eyes and noses of allergy sufferers.
6. Painting over damp ceilings and walls. Anti-mould paint applied to walls that are not fully dry traps moisture and spores beneath it. Within weeks the paint blisters and the mould breaks through.
7. Sharing towels and flip-flops. Especially in dormitories and in homes where relatives move in after a flood, this habit passes foot fungus and pink eye directly from person to person.

None of this means scrubbing is pointless. On the contrary, removing mud, scrubbing, discarding heavily contaminated items and drying everything are the foundation and must always come first. But bathrooms combine damp air, porous surfaces and corners a brush cannot reach, and ozone treatment is the extra step that handles what remains.

The answer: WHD residential ozone disinfection

World Health Disinfection (WHD) provides residential and building ozone disinfection for houses, condominiums, dormitories, hotels, offices, factories, schools and hospitals. Ozone (O3) is a strongly oxidising gas that breaks down the cell structures of bacteria, viruses and mould, as well as musty odour molecules, then reverts to oxygen (O2) leaving no chemical residue on tiles, towels or bedding.

Because ozone is a gas, it reaches ceiling boards, wall corners, the area behind the toilet, beneath the basin, ventilation openings and the air of the whole room, where mould spores and bacteria gather but hands cannot reach. According to test results the company has had certified by Thailand's Department of Medical Sciences and Intertek (UK), WHD's ozone process eliminates 99.99% of viruses, bacteria and mould. You can read more about our ozone cleaning service.

How the process works

1. Risk-point survey. The team inspects bathrooms, laundry rooms, bedrooms and corridors, looking at mould traces, moisture levels and residents' recent illnesses, to divide the building into zones.
2. Preparation. They confirm the space has been scrubbed and dried, remove heavily contaminated mats, curtains and towels for washing or disposal, open cupboards and drawers, set aside oxidation-sensitive items, and close doors and windows.
3. A completely empty space. People, pets and plants must leave the zone entirely. Ozone treatment is only done in an empty, closed space.
4. Ozone treatment. Professional ozone generators are used, typically for about 30 minutes per zone, adjusted to room size.
5. Rest and ventilation. The ozone is left to break down into oxygen and the space is then aired. Residents return only when the team says so.
6. Aftercare advice. The team advises on moisture control, looking after drains and shower heads, and keeping personal items separate.

Ozone treats the space, not the person. Anyone with an infected wound, pink eye or a skin rash needs medical treatment, and biofilm in drains still requires physical scrubbing alongside ozone.

10 reasons post-flood bathrooms and accommodation benefit from ozone

1. It reaches ceilings and upper corners. Spots where mould spores gather but people overlook are treated along with the rest of the room.
2. It genuinely removes musty smells. Ozone breaks odour molecules at the source rather than covering them with fragrance.
3. No residue to irritate skin or eyes. Because ozone reverts to oxygen, it suits people with sensitive skin, allergy sufferers and young children.
4. It covers shared spaces. Shared bathrooms, laundry rooms and corridors in dormitories and apartments can be treated zone by zone in one day. See the residential ozone service for details.
5. Backed by test results. Company test results certified by the Department of Medical Sciences and Intertek show 99.99% elimination of viruses, bacteria and mould.
6. Short turnaround. About 30 minutes per zone; even with rest time, the job is done in a day, so tenants are not displaced for long.
7. Safe, standard procedure. People, pets and plants are cleared, the area is sealed and a clear re-entry time is given.
8. Reassurance for tenants and parents. Owners can tell residents the building was disinfected by professionals. Learn more on the ozone service page.
9. It slows mould's return. Combined with good ventilation, it lowers the chance of mould coming back quickly.
10. Good value, with a bonus. Ozone jobs of 15,000 baht or more include a free medical-grade disinfectant spray for door handles, taps and grab rails.

Before and after ozone treatment

Example case: a twenty-room Hat Yai dormitory wins back trust

Note: this example case is compiled from common post-flood situations to illustrate the process. It is not a review from any particular customer.

As the dorm chat heated up, Nui did three things at once. First, people. She took her mother to a doctor straight away to have the foot wound examined, messaged every tenant advising anyone with pink eye, soggy skin or an inflamed wound to see a doctor, asked everyone not to share towels, pillows or flip-flops for the time being, and put liquid soap at every basin.

Second, a proper deep clean. Every bath mat and shower curtain was thrown away and replaced. A technician removed the drain grates and scrubbed the pipes and shower heads, scraped out mouldy silicone around the basins and resealed once the walls were completely dry, and repaired the worst-damaged grout. The flood-damaged extractor fans were replaced, and doors and windows on the ground floor were left open for several days to dry everything out.

Third, ozone. The WHD team divided the ground floor into five zones: the men's shared bathroom, the women's shared bathroom, the laundry room, the corridor, and the bedrooms that had flooded. Ground-floor tenants moved upstairs temporarily, and Nui's cat went to stay elsewhere. The team sealed and treated one zone at a time, about 30 minutes each, then rested and ventilated each area before tenants were allowed back. The upstairs bathrooms were treated the following day.

Many tenants noticed that the musty bathroom smell was clearly gone. Nui posted in the dorm LINE group explaining every step she had taken, from replacing mats and repairing grout to new extractor fans and ozone treatment, and asked everyone to help keep things clean. The mood in the group shifted from worry to understanding, and no more tenants moved out. Results in every building depend on its condition, the cleaning done before treatment, and moisture control afterwards.

Checklist for skin, eyes and bathrooms after a flood

Protect skin and eyes

• Avoid wading. If you must, wear boots, and wash your feet with soap and clean water as soon as you are out.
• Dry your feet thoroughly, especially between the toes, and put on clean, dry socks.
• If skin turns soggy, peels or itches, ask a pharmacist or doctor, and do not scratch it open.
• People with diabetes should check their feet daily and see a doctor for even a small wound.
• Wash hands often, do not rub your eyes, and never share face cloths, towels or pillowcases.
• Contact lens wearers must never rinse lenses or cases in tap water or floodwater; if eyes turn red, stop wearing lenses and see a doctor.

Before ozone day

• Remove mud and scrub floors, walls, basins and toilets with detergent, wearing gloves, a mask and eye protection.
• Remove drain grates and scrub pipes, shower heads and bidet hoses.
• Throw away mats, shower curtains, sponges and brushes that sat in floodwater.
• Dry the building within 24 to 48 hours, as WHO and CDC advise, and repair extractor fans.
• Arrange temporary places for people, pets and plants.

After ozone

• Re-enter only after the rest and ventilation period the team specifies.
• Run the extractor fan after every shower and leave the bathroom door open to let moisture out.
• Wash towels often and dry them fully in the sun.
• Wipe door handles, taps and grab rails regularly.
• If new mould appears, look for leaks inside walls or ceilings.

Frequently asked questions

1. Will ozone cure flood foot or pink eye?

No. Ozone deals with germs in the space; it does not treat disease. Anyone with symptoms should see a doctor or pharmacist. Ozone reduces sources of germs in bathrooms and living areas, lowering the chance of reinfection or spread to others.

2. My grout is very black. Will ozone make it white again?

Ozone kills mould and reduces odour, but pigment stains embedded in grout or silicone may remain. Badly damaged grout or sealant should be repaired or replaced first, and ozone then deals with the germs remaining in the room.

3. Can tenants stay in their rooms during treatment?

No. Ozone treatment must be carried out in an empty, closed space. People, pets and plants must leave the zone and return only after the rest and ventilation period the team specifies.

4. Do we need to scrub the bathroom first?

Always. Mud, soap scum and drain biofilm require physical scrubbing. Ozone is an additional step once the space is clean and dry.

5. How long does a multi-storey dorm or apartment take?

Typically about 30 minutes per zone, excluding preparation and rest time. Larger buildings can be done floor by floor or zone by zone so most tenants can carry on living normally. The team plans this after the survey.

6. Does ozone affect towels or bathroom items?

Ozone leaves no residue, but some materials, such as certain natural rubbers, can be sensitive to oxidation with repeated exposure. The team will tell you which items to remove before treatment.

7. Is there a promotion?

Ozone jobs of 15,000 baht or more include a free medical-grade disinfectant spray. Ask by phone or LINE.

A bathroom that is truly clean, not just clean-looking

Once scrubbing and drying are done, let WHD treat your bathrooms and living spaces with ozone to cut sources of skin infection, pink eye and mould in every corner.

Book Bathroom and Home Ozone Treatment

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

Related services

• Residential and building ozone disinfection
• Ozone cleaning service
• Ozone disinfection machines
• Contact the WHD team

References

• CDC: Floods – wound care and cleanup after a flood
• Department of Disease Control, Thailand: flood-related disease prevention