A typical scenario: the morning the water went down at Ton's gym

Ton runs a mid-sized gym in a three-unit shophouse in Bueng Kum. The ground floor holds free weights and cardio machines, the first floor has a class studio and locker rooms, and at the back there is a small pool for monthly members. On the night of 25 September he watched his CCTV feed on his phone as water seeped under the glass door. Within an hour the rubber flooring was a sheet of brown water. Three treadmills stood ankle-deep, the lower dumbbell rack was submerged, and murky street water spilled over the pool edge.

Two days later, as the water receded, Ton walked in with two staff members. The first thing that hit them was the smell: damp foam and soaked rubber, sewer odour pushed back up through the shower drains, and a fishy note from a pool so cloudy they could not see the bottom. Bench pads carried a neat brown line at the height the water had reached. Towels left in a laundry basket were already speckled black. The members' LINE group was buzzing with two questions: "When do you reopen?" and, more pointedly, "Will it be safe? The whole gym was underwater."

Ton knew the second question mattered more. A gym runs on trust. Members lie on benches, grip dumbbells with bare hands, walk barefoot in showers and get into the pool. If one person goes home with a rash, a stomach bug or a foot infection, that story will travel faster than any promotion he has ever run. This is a typical scenario rather than one specific business — but it is exactly what many Bangkok fitness operators are facing after late September 2026.

Why gyms and pools are especially high-risk after a flood

Urban floodwater is not clean rainwater. Public-health bodies such as the WHO and the US CDC warn that floodwater commonly carries sewage, household and commercial chemicals, fuel and debris. When it enters a building it deposits microorganisms on every surface it touches, and the thin film of silt left behind becomes food for bacteria and mold.

Gyms have features that raise the risk well above an ordinary office. First, they are shared spaces with intensive contact: one handle can be gripped by dozens of people a day. Second, skin touches surfaces directly and for long periods — benches, mats, grips and shower floors. Third, exercising bodies are sweaty and warm, and lifting or friction can cause small abrasions that give germs an easier route in. Fourth, gyms are usually closed, air-conditioned boxes, so humidity builds up quickly while ventilation systems are still being repaired.

Germs to think about in a post-flood gym

• Sewage-related bacteria, including intestinal bacteria such as Salmonella, carried in mud and tide marks on floors, benches and equipment. A hand that touches them and then a water bottle or face can lead to diarrhoea.
• Mold growing in rubber flooring, under interlocking tiles, inside foam pads, in gypsum walls and in air-conditioning ducts. Health agencies warn that materials left damp for more than 24–48 hours are likely to grow mold. Spores can aggravate allergies and asthma — particularly for people breathing hard during a workout.
• Skin and foot fungi thrive on constantly wet shower floors and pool decks where people walk barefoot. Extra contamination and humidity after a flood make these zones a priority.
• Contact-spread viruses such as norovirus, which causes vomiting and diarrhoea, and respiratory viruses like influenza and RSV that circulate easily in the rainy season and survive on frequently touched surfaces.
• Leptospira, the cause of leptospirosis, found in standing floodwater. Staff who waded through water or cleaned without boots — especially with cuts on feet or legs — should watch for fever and calf pain and see a doctor promptly if symptoms appear.

Who is most at risk

Gym members span every age group: older adults walking on treadmills or swimming for their health, children in swimming lessons, pregnant women in yoga classes, people with diabetes whose foot wounds heal slowly, and people with weakened immunity. When these members get infected, they tend to get sicker. That is why post-flood disinfection should be treated as a duty of care to vulnerable customers, not just a cosmetic clean. Staff doing the clean-up are also at risk, because they handle mud and contaminated water most directly.

What a rushed recovery costs a fitness business

Health. Members who return too early to a space that has not been properly disinfected may develop itchy rashes, athlete's foot, eye irritation from pool water that has not been rebalanced, diarrhoea from contaminated surfaces, or allergy flare-ups from mold spores. Staff working full shifts in musty air may suffer headaches, fatigue and more frequent illness.

Money. Every closed day means lost day passes, class fees, personal-training sessions and drink sales, while rent, salaries and equipment leases keep running. One Thai business report cited a Chamber of Commerce estimate of about 12,300 million baht in damage from this flood; small service businesses like gyms are part of that picture. A botched recovery that forces a second closure makes things worse.

Time. Wash quickly and reopen, and two weeks later mold may bloom under the rubber flooring, inside lockers or on the shower ceiling. You close again and redo the work — losing more time than doing it right the first time.

Reputation. In an era of online reviews and active member chat groups, one photo of black spots on a bench or one message saying "I picked up a foot fungus at the gym" can trigger cancellations. Gyms that communicate their recovery transparently gain a real advantage.

Members' families. People go home with gym bags, shoes and towels. Germs from a contaminated gym can reach small children or elderly parents at home — at a time when many Bangkok households are still recovering from the flood themselves.

Why the usual gym cleaning routine is not enough

Everyday equipment wipes. The sprays and wipes left out for members are designed for sweat and daily grime, not sewage-contaminated mud. They are also usually sprayed and wiped off immediately, without the contact time a disinfectant needs.

Bleach everywhere. Bleach has its place, but it is a poor fit for a whole gym. It corrodes metal, dulling or rusting stainless steel and aluminium machine parts; it dries and cracks vinyl upholstery; its sharp fumes bother people breathing deeply during exercise; and mixed with some toilet cleaners it can release dangerous gases. It also loses effectiveness when it meets heavy organic soil such as mud.

Fans plus air freshener. Fans do speed up drying, but they do not disinfect. Fragrances only mask odours. Members may smell something pleasant, yet mold under the flooring keeps growing, and the musty smell returns as the perfume fades.

Painting over, re-laying flooring on top. Covering up without removing soaked materials and disinfecting what is underneath simply traps moisture and mold. Sooner or later it seeps back as stains and odours that are harder to fix.

Assuming pool chlorine handles everything. A pool that has taken in a large volume of floodwater is not fixed by adding more chlorine. Heavy sediment and organic load undermine the pool's sanitiser. A professional pool contractor should assess the pool, drain and clean it if necessary, and rebalance the water before anyone swims.

Chemgene HLD4H: a medical-grade surface disinfectant for the gym, after the mud is gone

Once mud and grime are washed away, the next step is systematic surface disinfection. According to the product information, CHEMGENE HLD4H is a medical-grade high-level disinfectant made in England, used in hospitals, clinics, laboratories, schools, offices, airports, homes, and elderly and child care settings.

The product page lists activity against bacteria, fungi and mold, mycobacteria, Salmonella and a range of viruses including influenza H1N1, RSV, norovirus, hand-foot-and-mouth virus and SARS-CoV-2. It states that it kills within 1 minute, shows 99.85% efficacy against COVID-19, and provides residual surface protection for up to 14 days.

What makes it particularly suited to gyms is material compatibility. According to the product information, it is non-corrosive to stainless steel, aluminium, rubber, plastic and fibreglass — the core materials of machines, dumbbells, squat racks, rubber flooring, lockers and pool surrounds. It is biodegradable, and the page says it is safe for people, pets and medical equipment when used as directed. Dilutions range from 1:30, 1:50, 1:60 and 1:100 up to 1:200, so one product can cover heavy post-flood work and lighter daily maintenance after reopening.

For credibility, the product information lists tests and approvals from Mahidol University, NHS England, ISO 9001:2015, ISO 13485, SGS, Intertek, CE and the standards EN 13727, EN 14348, EN 13624 and EN 14476.

Step-by-step gym recovery

1. Safety first. Cut power to flooded floors and have an electrician check wiring, sockets and treadmill motors. Do not plug in any electrical equipment that sat in water until it has been cleared. Staff wear rubber gloves, boots and masks.
2. Document the damage. Photograph and video every zone for insurers and the landlord before you start removing things.
3. Strip out what cannot be saved. Waterlogged foam, studio carpets, curtains, towels, paper and swollen gypsum board should be removed and disposed of according to district guidance.
4. Shovel out mud and wash with clean water and detergent. Scrub floors, walls, machine frames and the space beneath machine bases. Lift interlocking rubber tiles and wash both sides — the underside is where mud and water collect most.
5. Dry. Open doors and windows, run fans and dehumidifiers, and aim to dry within 24–48 hours in line with general public-health advice.
6. Disinfect with Chemgene HLD4H. Dilute according to the label, spray or wipe all cleaned surfaces, and leave it for the contact time stated on the label. Prioritise high-touch points, showers and pool decks.
7. Ventilate and re-check. Air the space, check for odour and staining, and inspect for mold again the following week. If musty or chemical odours from repairs persist, consider the ozone chemical-residue and odour removal service, which is carried out in an empty, closed space.
8. The pool itself. Leave the pool water to a professional pool contractor. Use Chemgene on the surfaces around it — deck, ladder rails, loungers and showers — not as a pool water treatment.

Hot-spot map: where to disinfect first

Free-weight zone. Dumbbells, barbells, plates, racks and benches are gripped bare-handed all day. Brush mud out of knurling and textured grips, rinse, dry, then apply Chemgene at the label dilution.

Cardio zone. Treadmills, bikes and cross-trainers — handles, buttons and touchscreens. For electronics, spray onto a cloth first and wipe; never spray directly into screens or vents. Have the manufacturer's technician check motors before reuse.

Pads and mats. Vinyl-covered pads with no tears can be washed and disinfected on the outside. If water got into the foam, replace the foam or reupholster. Studio yoga mats that were submerged are usually best replaced.

Locker rooms and showers. Inside and outside lockers, door handles, benches, shower heads, taps, tiled floors and grout lines, floor drains and soap shelves — permanently damp areas where people walk barefoot.

Pool surrounds. Non-slip decking, ladder rails, loungers, poolside changing rooms and any footbaths. Remove all sediment first, then disinfect surrounding surfaces, taking care that muddy rinse water does not run back into the pool.

Reception and shared touchpoints. The front desk, membership card scanners, water dispensers, stair rails, door handles and lift buttons — everyone passes through them.

10 reasons Bangkok gyms choose Chemgene HLD4H for post-flood recovery

1. Medical grade, made in England. According to the product information, it is a high-level disinfectant used in hospitals and clinics. See the Chemgene HLD4H product page.
2. Broad coverage of gym-relevant germs. The product page lists bacteria, fungi, Salmonella and multiple viruses.
3. Fast action. The page states it kills within 1 minute, helping crews work steadily across large floor areas.
4. Residual protection. Up to 14 days of surface protection, per the product information — useful in the busy first fortnight after reopening.
5. Kind to expensive equipment. Non-corrosive to stainless steel, aluminium, rubber and plastic, reducing the risk of rust on costly machines.
6. Suitable for showers and pool decks. Fibreglass and plastic fixtures are on the list of compatible materials.
7. Flexible dilution. From 1:30 to 1:200 — heavy-duty for recovery, lighter for daily use, which helps control costs.
8. Biodegradable. Easier on the building's wastewater system than large volumes of harsh chemicals.
9. Documentation you can show members. Listed tests and standards such as Mahidol University, NHS England and EN norms let you explain your process with evidence.
10. Local advice in Thailand. Ask about dilutions or a whole-gym plan via World Health Disinfection — call 065-556-6294 or LINE @whd268.

Before and after: what a systematic recovery looks like

Example case: a yoga and Pilates studio near Khlong Chan

This example case is an illustrative scenario, not a verified customer review. Mind owns a small yoga and Pilates studio in a two-storey building near Khlong Chan. The ground floor holds five reformers; upstairs is the yoga room. Water rose about a hand-span on the ground floor. It does not sound like much, but the laminate floor swelled, reformers with aluminium frames and vinyl pads sat in water, and a musty smell drifted upstairs.

Mind started by photographing everything. She removed the swollen laminate, threw out the soaked studio mats, carried the reformers upstairs temporarily, washed the frames with detergent and water, dried them and applied Chemgene HLD4H at the label dilution to frames, springs, handles and pad surfaces. Because the product information states it is non-corrosive to aluminium and rubber, she was less worried about dulling the finish on expensive machines.

With the laminate gone, she dried the concrete slab with fans and a dehumidifier for several days, disinfected the surface and only then had new flooring installed. Before the first class she posted every step on her page, named the medical-grade disinfectant she used, and asked members to bring their own mats for the first week. Most members rebooked, and several said the clear explanation was what reassured them. The lesson: a good recovery is not just clean — it is visibly, explainably clean.

Reopening checklist for gyms and pools

Before disinfecting

• Electrician has checked wiring, panels and every appliance that was submerged
• Waterlogged, rotting materials removed and photographed
• Mud washed from every surface, including under flooring and machine bases
• Space dried with ventilation, fans and dehumidifiers
• Staff wearing gloves, boots, masks and eye protection when spraying

During disinfection

• Dilute Chemgene HLD4H according to the label; never mix with other chemicals
• Work zone by zone, from cleaner areas to dirtier ones
• Respect the label contact time
• Log the date, time, zone and person responsible so you can share it with members

After disinfection and after reopening

• Re-inspect for musty smells and mold weekly for at least a month
• Increase wipe-downs of high-touch points for the first two weeks
• Place hand sanitiser and equipment wipes at the entrance and in every zone
• Post signs asking members to wear sandals in showers and around the pool
• Ask members with open wounds to cover them before swimming, and anyone with fever, diarrhoea or calf pain after wading to stay home and see a doctor

How to bring members back with confidence

After a disaster, transparency is your best marketing. Announce a firm reopening date rather than shifting it repeatedly, and explain briefly what you did: which materials were removed, how you washed, which disinfectant you used, whether the electrics were inspected and who serviced the pool. Before-and-after photos help enormously.

Avoid overclaiming. Phrases like "100% germ-free" or "zero infection risk" are promises no facility can keep. Use honest wording such as "every zone washed and surface-disinfected with a medical-grade disinfectant according to label directions", and describe the ongoing measures after reopening. Vulnerable members may want to wait a little longer; offering a free freeze or membership extension protects the long-term relationship.

For gyms inside condominiums or housing estates, juristic persons should notify residents through their usual channels and make it clear whether the gym is open while the pool is still awaiting water treatment, or whether both reopen together, to avoid confusion.

Frequently asked questions

Can I pour Chemgene HLD4H into the pool instead of chlorine?
No. Chemgene HLD4H is a surface disinfectant. Post-flood pool water must be assessed, drained and cleaned if needed, and rebalanced by a professional pool contractor. Use Chemgene on decks, ladder rails, benches and showers.

Can I spray Chemgene straight over the mud to save time?
No. Always remove mud and wash surfaces first; mud and organic soil prevent the disinfectant from reaching the surface. Then apply Chemgene at the label dilution and contact time.

Will it rust metal gym equipment?
According to the product information, it is non-corrosive to stainless steel, aluminium, rubber, plastic and fibreglass. Dry equipment as usual, and for electronics spray onto a cloth before wiping.

When can members use the space after disinfection?
Once the label contact time has passed, surfaces are dry and the space is well ventilated. Your actual reopening date should also depend on electrical and air-conditioning checks and a follow-up mold inspection.

A bench pad sat in water overnight. Can I wash and disinfect it?
If water got into the foam, disinfecting the outside is not enough — replace the foam or reupholster. Pads with intact covers and dry foam can be washed and surface-disinfected.

The musty smell is still there after disinfection. What now?
Look for hidden moisture under floors, inside gypsum walls or in AC ducts and fix the source first. For lingering musty or paint odours from repairs, ask about ozone chemical-residue and odour removal, done only in an empty, closed space.

A staff member who helped clean now has fever and calf pain. What should they do?
See a doctor immediately and mention the floodwater exposure, as these can be signs of leptospirosis. Disinfectants reduce surface risk; they are not medical treatment.

Get your gym ready for members again

Talk to World Health Disinfection about dilutions and a disinfection plan for your gym, studio or pool area.

Order Chemgene HLD4H for Your Gym

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

Related links

• Chemgene product range
• Disinfection services for buildings and businesses
• Ozone odour and chemical-residue removal
• Contact World Health Disinfection

References

• 2026 Bangkok floods — Wikipedia
• Al Jazeera: Disaster zone declared across Bangkok
• CDC: Floods
• WHO fact sheets