Last updated: 1 Oct 2026 | 14 Views |
When people think of flooding, they picture single-storey houses by a canal. The Bangkok floods of late September 2026 made it clear that high-rise condominiums are affected too; the damage simply concentrates at the very bottom of the building: the basement car park, plant rooms, the bin room, the lobby and the lifts. These are the shared spaces every resident passes through every day. According to news reports, as of 30 September some roads, including Lat Phrao, still had 20 to 40 cm of standing water. This guide is for condo juristic persons, housekeeping teams, building technicians and residents who want to know how common areas should be restored so that they are safe for everyone in the building.
A typical scenario (an illustrative situation based on common experiences, not a review from any specific customer)
Prae, 34, is the juristic manager of a 25-storey condo on a soi off Lat Phrao Road. The building has two basement parking levels and around 400 units. On the night of non-stop rain, water from the street poured down the ramp faster than the sump pumps could cope. Within hours the lowest basement level was a murky pool, with several cars submerged up to their doors. The technical team cut power to the basement and stopped the lift that serves the underground floors.
Three days later, with the water finally pumped out, the scene was thick mud on the concrete floor and every column, overturned bins in the bin room, rubbish wedged into corners, and a stench of sewage mixed with engine oil strong enough that staff needed masks. Upstairs, water had barely entered the lobby, but the entrance carpet was soaked, the reception sofas were stained and the marble floor was covered in muddy footprints from residents wading home.
The office phone never stopped. One resident asked when the lift would be back. Another asked whether they could fetch their car. Someone posted a photo of a mud-smeared lift button in the building's LINE group with the words: "Who would press this?" A mother on the 12th floor asked when the children's playroom would reopen, and whether it was really safe.
Prae knew that clearing mud was non-negotiable. The harder part was answering "Is it really clean?" for hundreds of residents who share the same spaces. She needed a clear plan, a correct sequence, and a disinfectant that could be used on lift stainless steel, lobby surfaces and metal door hardware without damaging them.
Condos differ from houses in one key way: many people touch the same surfaces within a short time. A single lift button may be pressed hundreds of times a day; everyone grabs the entrance door handle; the key-card reader is tapped constantly. When these areas are contaminated by floodwater, germs can pass from person to person quickly.
The basement sits below street level, so the water that flows in comes from roads and public drains, often contaminated with sewage, fuel, engine oil and rubbish. Once the water is pumped out, all that sediment stays on the floor, columns, walls and drainage channels. The car park is also an enclosed space with limited airflow, so moisture lingers and mould thrives.
Even if water barely entered, everyone wading along the street brings mud in on shoes, bags and wet umbrellas. Entrance mats, sofas, the security counter, mailboxes and the parcel area become secondary contamination zones, all the more so during a flood, when parcel and food deliveries surge.
A lift car is a small enclosed space where people stand close, share air and press the same buttons. When some lifts are out of service after a flood, the rest become even more crowded. Handrails, stainless steel walls and buttons, inside the car and at every landing, deserve special attention.
Older residents usually depend on lifts and cannot avoid shared touch points. Small children love pressing lift buttons and touching walls. Pregnant residents and people with chronic illnesses should be told which areas are still being cleaned. And the housekeepers and technicians who clean the car park have the most direct contact with floodwater and mud, so the juristic person should equip them properly.
Health. If several units report diarrhoea or fever at the same time, the news spreads through the building's chat group fast, and common areas are the first thing people question.
Property and cost. One Thai business report cited a Chamber of Commerce estimate of about 12,300 million baht in damage from this flood. For a condo, costs come from repairing electrical systems, pumps, lifts and cleaning large areas. Choosing a cleaner that corrodes metal can add later repair bills for lift button panels, stainless doors and aluminium fittings.
Time and management. Every day the car park or lifts stay closed, residents park outside, climb fire stairs and phone in complaints. A staged plan allows areas to reopen one at a time, safely.
Trust. A juristic office that clearly communicates what was cleaned, with what and when earns far more trust than one that simply says "it has been cleaned", which matters for the atmosphere of the building and long-term unit values.
Pressure-washing and calling it done. A pressure washer moves mud well but does not disinfect, and careless spraying throws dirty mist onto columns, walls and other cars.
Using strong bleach on everything. Bleach corrodes lift stainless steel, handrails and aluminium door frames, and can dull or stain stone. Its fumes in a poorly ventilated car park are also hazardous for staff working long shifts.
Spraying directly onto lift button panels. Liquid can seep into the circuitry and cause faults. The right way is to wet a cloth and wipe.
Reopening lifts before the lift company inspects them. Any lift whose pit was flooded must be checked by its maintenance contractor before use. Disinfecting the car comes after engineering safety is confirmed.
Not telling residents the cleaning schedule. Residents walk into freshly treated or slippery areas, risking accidents and unnecessary chemical contact.
After mud is removed and surfaces are washed, the next step is systematic disinfection. Chemgene HLD4H medical-grade disinfectant suits condominiums because it can be used on the wide range of materials found in common areas.
According to the product information, CHEMGENE HLD4H is a medical-grade high-level disinfectant made in England, listed as effective against bacteria, fungi and mould, mycobacteria, Salmonella and viruses including influenza H1N1, RSV, norovirus, hand-foot-and-mouth virus and SARS-CoV-2. The product page states it kills within 1 minute, achieves 99.85% against COVID-19, and protects surfaces for up to 14 days.
The key advantage for condos is that, according to the product information, Chemgene is non-corrosive to stainless steel, aluminium, rubber, plastic and fibreglass: exactly the materials of lift cars, handrails, entrance doors, glazing frames and door seals. It can be diluted at 1:30, 1:50, 1:60, 1:100 or up to 1:200 as the label specifies. It is biodegradable, which matters when large volumes of rinse water from the car park flow into the building's treatment system and public drains. The product page says it is safe for people, pets and medical equipment when used as directed.
On standards, the product information lists Mahidol University, NHS England, ISO 9001:2015, ISO 13485, SGS, Intertek, CE and EN 13727, EN 14348, EN 13624 and EN 14476, with use in hospitals, clinics, offices, airports, schools and homes. This helps a juristic office explain to the committee and residents exactly which product was chosen and why.
Remember: Chemgene does not prevent flooding and is not a medical treatment. It is a step that helps reduce infection risk from surfaces after mud has been washed off. Anyone who is unwell should see a doctor, and electrical systems and lifts must always be checked by qualified specialists first.
According to news reports, this flood included a death by electrocution in a car park, a sobering reminder that before anyone works in a basement that is still wet, power to that area must be cut and an electrician must check the system, distribution boards, EV charging points and light fittings. Never use power tools while standing in water, and assign a safety lead for each work area.
Step 0: Plan and communicate. Divide the building into zones with a sequence and schedule. Notify residents through notices at the lifts and the LINE group: which areas are closed, which have reopened, and please do not enter cordoned spaces. Provide staff with rubber gloves, boots, masks, eye protection and coveralls.
Zone 1: Lobby and entrance (first, because everyone uses it). Remove soaked entrance mats for disposal or proper laundering. Mop stone or tile floors with a cleaner suited to the material, leave just damp, then disinfect. Wipe glass-door handles, card readers, intercom buttons, the security counter, mailboxes, parcel shelves and hard sofa arms. Fabric sofas stained by dirty water should be assessed for deep cleaning or replacement. Put down fresh dirt-trapping mats and a hand-sanitising point at the entrance.
Zone 2: Lifts (after the lift company approves use). Start inside the car: clean stainless walls from top to bottom, handrails and floor with a cleaner, then disinfect with Chemgene at the label dilution. For button panels inside the car and at every landing, dampen a microfibre cloth and wipe; never spray directly. Wipe door edges and sill tracks, where mud collects. Keep surfaces wet for the label contact time. For the first two weeks after the flood, increase button-wiping to several times a day.
Zone 3: Fire stairs and lift lobbies on each floor. With lifts out of action, residents use the fire stairs more, so handrails and fire-door handles are key shared touch points. Wash mud off the lower steps, then disinfect the full handrail and door handles on every floor.
Zone 4: The basement car park. The biggest job. Once the electrician confirms it is safe, shovel mud from the floor, ramp and drainage channels; hose sediment off walls and columns from top to bottom; remove oil stains with a degreaser first; then disinfect hand-contact points such as the ticket machine, barrier buttons, handles on doors into the building and crash rails, plus the pedestrian route from parking bays to the lift lobby. Keep the car-park ventilation fans running to reduce humidity.
Zone 5: Bin room and refuse points. A flooded bin room is a concentrated source of germs and may attract rodents. Remove all waste, wash bins and floor with detergent, then disinfect bins inside and out, lids, door handles and the floor. Check for gaps where animals can enter and consider pest control.
Zone 6: Plant and pump rooms. Technicians and specialists must inspect machinery first. Disinfect only external surfaces such as floors, door handles and outer control panels, following equipment manufacturers' guidance. Check whether floodwater entered the building's water tanks; if so, specialists must clean the tanks and test water quality before supply resumes.
Zone 7: Other shared facilities. If the gym, playroom, laundry room or residents' meeting room is on a low floor and was flooded, wash and then disinfect high-touch items such as gym handles, plastic toys, coin-operated machines and tables. The playroom should reopen near the end, after a re-check that it is fully dry and free of musty smells.
Ongoing care. After each zone reopens, set a daily wiping schedule for shared touch points (lift buttons, entrance handles, card readers and handrails) while residents are still carrying damaged items down and outside contractors are coming and going.
Large buildings can consider the WHD professional disinfection service, and if paint or musty smells linger after common areas are repaired or repainted, see ozone chemical-residue and odour removal, carried out in an empty, closed space.
Example case (a simulated scenario to explain the process, not a real customer review)
Ton, 41, chairs the committee of an eight-storey low-rise condo. The ground-level car park took about half a metre of water and the building's only lift stopped working. Most residents are families with small children or older relatives.
Ton began with an online committee meeting and split the work into three phases. Phase one made the entrance and lobby safe: floors washed, mats discarded, and door handles, card readers and mailboxes wiped with Chemgene at the label dilution. Phase two waited for the lift company's inspection; once it was cleared, the car was cleaned, every landing button was wiped with a dampened cloth, and housekeeping wiped buttons four times a day for the first two weeks. Phase three was the car park, which waited for the electrician to check wiring and EV chargers before mud was shovelled out, oil stains removed and touch points disinfected.
At each phase Ton posted notices in the LINE group with photos and the name of the product used. Residents knew what had reopened and what had been done; questions in the group dropped noticeably. The playroom reopened last, after a check that it was completely dry. Transparent communication mattered as much as the quality of the cleaning.
Q: Can we spray Chemgene onto lift buttons?
A: Do not spray button panels or electronics directly. Dampen a cloth and wipe, and follow the lift company's guidance.
Q: Can it be used on a stone lobby floor?
A: The product information lists compatibility with stainless steel, aluminium, rubber, plastic and fibreglass. For natural stone or special finishes, test a small hidden area first and ask the WHD team.
Q: The car park is huge. Do we need to disinfect the entire floor?
A: Wash mud from the whole area, and focus disinfection on what people touch or walk through most: the walkway to the lifts, ticket machines, barrier buttons, door handles and the bin room.
Q: With 14-day protection, can we stop wiping lift buttons?
A: No. Surfaces touched hundreds of times a day should be cleaned and disinfected regularly, especially in the weeks after a flood.
Q: Can residents use it inside their own units?
A: Yes, on door handles, bathrooms and other surfaces according to the label, particularly where sewage backed up through drains.
Q: A staff member who cleaned the car park has a fever. What now?
A: Stop work and see a doctor right away, mentioning the floodwater exposure, as it could be leptospirosis or another infection. A disinfectant is not a treatment.
Wash the mud away, then disinfect the car park, lobby and lifts with a medical-grade disinfectant that does not corrode stainless steel. Ask us about building-scale quantities.
Order Chemgene HLD4H for Your Condo
Phone 065-556-6294 · LINE @whd268 · Email worldhealthdisinfection@gmail.com
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