A typical scenario (an illustrative situation, not a review from any specific customer)

"One capful per bucket": a recipe nobody could verify

Lek runs a small noodle shop on the ground floor of a two-unit shophouse in a soi off Lat Phrao. In late September 2026, water from the street poured in, rising over the stainless table legs, the drinks fridge and the bathroom at the back. It took days to drain, and the road outside kept flooding on and off. Lek and her son shovelled mud, hosed the floor and scrubbed the walls until they looked clean. Then she opened, for the first time, the bottle of medical-grade disinfectant her daughter had ordered for her.

The trouble started the moment she read the label. There were several numbers: 1:30, 1:50, 1:60, 1:100 and 1:200. Which one was for the shop floor? Which for the tables customers eat at? Which for the bathroom? Her son suggested "one capful per bucket should do". The aunty next door insisted "pour in plenty; after a flood like this you need it strong". In the end Lek eyeballed it. Some buckets were so strong the floor turned sticky; others so weak she doubted they did anything. And the concentrate she had planned to stretch across the whole shop ran down far faster than expected.

Lek's story is extremely common after floods. People choose a good product and then slip on the small step that matters most: diluting it correctly according to the label. This guide shows you how to read dilution ratios, calculate millilitres of concentrate yourself, divide a home or shop into zones that match the task categories on the label, and set up a mixing routine anyone in the household can repeat without guessing.

Context: the recovery phase after the late-September 2026 Bangkok floods

According to news reports, around 300 mm of rain fell in roughly 48 hours between 24 and 27 September 2026, causing widespread flooding in Bangkok. On 26 September the Bangkok Metropolitan Administration declared all 50 districts a disaster zone, with eastern Bangkok hit hardest. Governor Chadchart said the canals were full and drainage would take two to three days after the rain stopped. As of 30 September, some roads such as Si Burapha and Lat Phrao still had 20 to 40 cm of water.

In recovery, households and shops must clean and disinfect large areas in limited time. Mixing the product correctly is not a detail; it decides whether the disinfectant performs as designed. Remember that disinfectants only help reduce infection risk from surfaces during recovery. They do not prevent floods and are not medical treatment. Anyone with fever, calf pain, diarrhoea or an infected wound after wading should see a doctor.

Why dilution matters more than you think

Concentrated disinfectants are not designed to be used neat. The manufacturer tests performance at a specific concentration with a specific contact time and prints both on the label. Those numbers are a proven recipe. Change the recipe and the result becomes unpredictable.

Too weak

The solution contains less active ingredient than was tested, so some germs may survive, particularly in heavily contaminated flood areas such as bathroom floors, drains and lower walls. The result is false confidence: the family believes the house is disinfected when it has not reached the intended level.

Too strong

Many people believe more is safer. In reality, exceeding the label does not meaningfully improve disinfection. It wastes concentrate, leaves sticky or slippery residue, raises the chance of skin and airway irritation, and creates extra rinsing work. In a restaurant or a home with toddlers, unnecessary residue on tables and floors is exactly what you want to avoid.

Dilution and contact time are a pair

A good label pairs each dilution with a contact time for each type of task. Mixing correctly but wiping too soon falls short, just as leaving a too-weak solution on for longer does. The Chemgene HLD4H product page states that it kills within one minute, but the contact time you actually use for each job should always follow the label that comes with your bottle.

Floods make mixing errors more likely

Normally you might mix one spray bottle a week. After a flood you mix several buckets a day, while exhausted, with several people helping and whatever containers are at hand. Every one of those factors increases the chance of error, which is why a clear measuring system helps so much.

Reading 1:30 to 1:200

According to the product information, Chemgene HLD4H can be diluted at 1:30, 1:50, 1:60, 1:100 and up to 1:200. The first number is concentrate; the second is water. The easiest rule to remember: the smaller the second number, the stronger the solution. So 1:30 is the strongest in this set and 1:200 the weakest.

Ratios are written two ways in practice. One means 1 part concentrate plus 30 parts water, 31 parts in total. The other means 1 part concentrate in 30 parts of finished solution. The difference is small in real life, but check the label's explanation or ask the supplier to be sure. The table below assumes the first convention, 1 part concentrate to the stated parts of water, rounded for practical measuring.

The formula to work it out yourself: concentrate = volume of solution you want, divided by (the second number plus one). For 2 litres at 1:50, that is 2,000 divided by 51, about 39 ml; the rest is clean water. This table is arithmetic to help you measure. It does not say which ratio suits which job; that comes from the product label.

For small volumes such as 2.5 or 5 ml, use a needle-free plastic syringe or a graduated medicine cup. Capfuls vary between brands, wet or partly filled caps change the amount every time, and the error adds up across a day of mixing.

Divide the home into zones, then match each zone to the label

To mix correctly every time, stop thinking in rooms and start thinking in contamination level and surface use, then match each zone to a task category on the label. A general principle of concentrated disinfectants is that heavily contaminated or high-level tasks usually call for a stronger ratio on the label, while routine maintenance usually uses a weaker one. The actual number for each task must be read from the Chemgene HLD4H label on your bottle.

Zone 1: direct flood-contact, heavy contamination

Ground floors, walls below the water line, door sills, the bottom stair steps, garages, car parks and around drains. These sat in sewage-laden water. Remove all mud first, then use the label ratio for heavily contaminated surfaces, allow the full contact time, and repeat the next day if people are still tracking mud in.

Zone 2: bathrooms and sanitation points

Toilets, seats, bathroom floors, grout, basins and floor drains. During floods, septic systems can back up, making bathrooms another high-contamination point. Use the label ratio for sanitary ware or high-contamination areas, and never combine it with other toilet cleaners in the same bucket.

Zone 3: kitchens and food-contact surfaces

Counters, prep tables, customer tables, dish racks, stainless table legs, fridges and sinks. Per the product information, Chemgene is non-corrosive to stainless steel and aluminium, which suits metal-heavy kitchens. Check the label specifically for the food-contact ratio and whether a clean-water rinse is required afterwards. Food and porous utensils that sat in flood water should be thrown away, not disinfected.

Zone 4: high-touch points

Door handles, switches, stair rails, remote controls, lift buttons in condominiums, cash drawers and touch screens the manufacturer allows to be wiped. They were not submerged but are touched dozens of times a day by muddy hands. This is usually frequent maintenance work: use the label ratio for general surfaces and spray onto a cloth rather than directly onto electrical items.

Zone 5: children's, older adults' and pets' areas

Play corners, plastic toys, bed frames, grab rails, pet bowls and cages. Here you balance effective disinfection against minimal residue. The product page says it is safe for people and pets when used as directed; use the label ratio for that task, follow any rinse instructions, and let surfaces dry completely before children or pets return.

Zone 6: cleaning tools and wading gear

Boots, buckets, brushes, mops, shovels and reusable gloves. They touch mud every day, and if they are not disinfected they carry germs from Zone 1 into every other zone. Wash them, then soak or spray at the label ratio and dry before storing.

Your own worksheet: fill in the numbers from the label

Print this, fill in the numbers from your label and stick it next to your mixing point, so everyone in the house or shop mixes the same way every time. If the label is unclear or you are not sure which category a job falls into, ask the WHD team on 065-556-6294 or LINE @whd268 before you start.

What wrong dilution costs during recovery

Health: too weak, and flood-borne germs may remain on surfaces everyone believes are safe. Too strong, and people sensitive to chemicals, such as those with asthma or allergies, are more easily irritated.

Money: concentrate meant to last weeks can be gone in days when every bucket is overdosed. With repair bills already high, measuring correctly is the simplest saving available.

Time: overly strong solutions leave residue that needs rinsing; overly weak ones leave you unsure and repeating the job. Both waste hours.

Business: for a shop like Lek's, a clear, repeatable disinfection routine helps it reopen with confidence and lets staff explain to customers how the premises were cleaned.

Family: when everyone mixes the same way, small arguments about who got it wrong disappear. Post-flood exhaustion turns small frictions into big ones, and a clear system lightens the load.

Common mixing mistakes after floods

• Measuring by capful or "a glug", so every bucket is a different strength.
• Using dirty water, such as water stored during the flood or water from a bucket just used for mud. Organic matter weakens the disinfectant before you use it. Use clean tap water.
• Pouring concentrate into an empty bucket and blasting water on top, causing foam and splashes. Add water first, then concentrate, and stir gently.
• Mixing with detergent or another product in the same bucket. Never mix with anything. Wash with detergent, rinse, then disinfect from a separate bucket.
• Reusing bottles from other chemicals. Residues can react or cause confusion. Use new or thoroughly cleaned bottles, clearly labelled.
• Leaving mixed bottles unlabelled, so two days later nobody knows the ratio or the mixing date.
• Mixing more than you will use that day. If the label does not state a shelf life for diluted solution, mix only what you will finish the same day.
• Spraying onto mud. Even a perfect mix underperforms on a dirty surface.

Know Chemgene HLD4H before you mix

According to the product information, CHEMGENE HLD4H is a medical-grade high-level disinfectant made in England. It lists activity against bacteria, fungi and mould, mycobacteria, Salmonella and viruses such as influenza H1N1, RSV, norovirus, hand-foot-and-mouth disease virus and SARS-CoV-2. The product page states it kills within one minute, is 99.85% effective against COVID-19 and provides surface protection for up to 14 days.

It is biodegradable; non-corrosive to stainless steel, aluminium, rubber, plastic and fibreglass; and described as safe for people, pets and medical equipment when used as directed. Listed tests and approvals include Mahidol University, NHS England, ISO 9001:2015, ISO 13485, SGS, Intertek, CE and EN 13727, EN 14348, EN 13624 and EN 14476. It is used in hospitals, clinics, laboratories, schools, offices, airports, homes and elderly and child care.

The wide dilution range, from 1:30 to 1:200, lets one bottle of concentrate cover many task types, from heavily contaminated zones to daily wiping of touch points. The only condition is measuring to the task on the label.

Standard mixing and application steps

1. Wear gloves and boots, plus eye protection or a mask when mixing large volumes. Open windows.
2. Wash the surface free of mud with detergent and water, then rinse.
3. Check the label for the task that matches your zone and note the ratio and contact time.
4. Add clean tap water to a graduated container first.
5. Measure concentrate with a cup or needle-free syringe using the table, add it to the water and stir gently.
6. Label the bottle or bucket with the ratio, the zone and the date.
7. Spray or wipe until evenly wet, leave for the label contact time, then let dry or wipe as instructed.
8. Clean tools, wash hands, and store the capped concentrate high up, out of children's reach.

10 reasons correct Chemgene dilution pays off

1. Performance as tested, because you use the concentration on the label.
2. Concentrate lasts longer when every dose is measured.
3. One bottle, many jobs. Chemgene HLD4H dilutes from 1:30 to 1:200 per the product information.
4. Less residue and slipperiness on tiles and tables, with no extra rinsing.
5. Kinder to materials, together with its non-corrosive profile on stainless steel, aluminium, rubber and plastic.
6. Safer for the household, with no excess residue around children and older adults.
7. Everyone mixes the same way using a worksheet by the mixing point.
8. Traceable, because labels show ratio and date, so you know when to remix.
9. Suits shops and businesses that need a standard routine before reopening. See product details.
10. Full use of residual protection, which the product page cites at up to 14 days when used correctly on clean surfaces.

Before and after a mixing system

Example case: the noodle shop that reopened with a mixing routine

Example case (an illustrative scenario, not a real customer testimonial)

Back to Lek's shop. After two days of guessing, her daughter called the WHD team about dilution, then helped her mother build a six-zone worksheet from the label and printed it next to the hand basin at the back. They bought two sets of medicine cups and needle-free syringes and split the spray bottles into three, each with a different coloured label: one for floors and the bathroom, one for customer tables and the counter, and one for touch points such as the fridge handle and the cash drawer.

Each morning before opening, her son washes the front floor where customers track in mud from the street, then disinfects it from a bucket mixed to the worksheet. Lek wipes the customer tables with the bottle mixed for food-contact surfaces and follows the label's rinse guidance. She found the remaining concentrate lasting far longer than expected, the floor no longer turning sticky, and when regulars asked how the shop had been cleaned after the flood, she could explain with confidence.

Meanwhile Lek kept watching her own and her son's health after days of wading, ready to see a doctor at any fever or calf pain, because she knows disinfectant looks after surfaces, not bodies.

Checklist before and after mixing

Before mixing

• Read the whole label, including warnings and first aid.
• Prepare measuring cups, a needle-free syringe, a graduated container and new spray bottles.
• Use clean tap water, not water stored during the flood.
• Remove all mud from the area to be disinfected.
• Put on gloves and boots and open the windows.

After mixing and use

• Label every bottle with ratio, zone and date.
• Store concentrate capped, in the shade, away from children and pets.
• Dry the building quickly; CDC general guidance is to clean and dry within 24 to 48 hours to limit mould.
• If musty or paint and thinner odours linger after repairs, consider ozone odour and chemical-residue removal, done in a closed space with no people, pets or plants inside.
• Watch everyone's health. Fever, calf pain, diarrhoea or infected wounds mean a doctor's visit.

Frequently asked questions

What is the difference between 1:30 and 1:200?

1:30 is much stronger than 1:200; the smaller the second number, the stronger the mix. Which ratio applies to which job is set by the label.

Can I measure with the bottle cap?

It is not recommended. Cap sizes vary and are easily under-filled. A graduated cup or needle-free syringe is far more accurate.

Can I mix with warm water?

Follow the label. If it says nothing, clean tap water at room temperature is the safe choice.

Can I keep a mixed solution for tomorrow?

Check whether the label states a shelf life for diluted solution. If not, mix only what you will use that day and date every bottle.

Do I rinse dining tables after spraying?

Follow the label's food-contact instructions exactly. If unsure, ask WHD before use.

What if I accidentally mixed it too strong?

Add clean water to bring it back to the calculated ratio. For skin or eye contact, follow the first-aid instructions on the label and see a doctor if symptoms occur.

Mix it right, disinfect to standard, make every drop count

Chemgene HLD4H, a medical-grade disinfectant diluted from 1:30 to 1:200 according to the label.

Order Chemgene HLD4H

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

Related services and pages

• All Chemgene products
• Professional disinfection service
• Certificates
• Contact us

References

• 2026 Bangkok floods (Wikipedia)
• Al Jazeera: Disaster zone declared across Bangkok
• CDC: Floods