Instructions for handling contaminated water sources after floods

Specialist Doctor 1 Bui Thi Thuy Ngan - Head of the Department of Environmental Health, School Health, Nghe An Province Center for Disease Control stated: During floods, the environment is polluted by dead animals and waste. People in flood-affected areas are susceptible to gastrointestinal diseases, skin diseases, colds, flu and dengue fever.

To proactively prevent epidemics, people need to ensure safe and hygienic food selection and preparation, eat cooked food and drink boiled water; regularly wash hands with soap, and practice daily personal hygiene.

All people need to follow the principle of cleaning up as the water recedes; collecting, processing and burying animal carcasses according to the instructions of medical staff; destroying larvae, pupae, and mosquitoes; using mosquito nets when sleeping even during the day... When there are signs of suspected infection, it is necessary to go to the nearest medical facility for examination and treatment.

After the floodwaters recede, measures must be taken to immediately treat the water source to prevent the risk of infection and health effects. Specifically, clean water tanks, wells, water containers and use chemicals to disinfect drinking water and domestic water according to the instructions of medical staff.

To dredge and clean the well:People need to clear all stagnant water around the well area; remove the lid or plastic sheet covering the well mouth. Before making the water clear and disinfecting, the well must be dredged; use well water to pour over the well wall to wash away all sand, dirt, and debris stuck on the well wall and floor.

If the well is flooded and has turbid water, it is necessary to drain the water and remove all the mud. In case it cannot be dredged, choose another well to treat and share. If all the wells in the area cannot be dredged, temporary treatment measures can be applied such as drawing a few dozen liters of water to the tank, then adding alum and disinfecting. After that, the treated water can be used temporarily. When the water is used up, perform other batches for use; wait a few days until the well water level drops and then proceed to dredge.

In case there is no alum to clarify the water source, you can make a temporary sand filter tank with a barrel, bucket or jar with a capacity of about 20 - 30 liters of water. Punch a hole with a diameter of about 1 cm on the wall, 5 cm from the bottom of the barrel. Put some stones or broken bricks at the bottom, put a piece of burlap on top and pour sand about 25 - 30 cm thick. Pour in well water until the water flows out clear, then use it to disinfect.

If the well is flooded but the floodwater has not overflowed and the water is still clear, it must still be sterilized before use. If conditions permit, the water should be drained and dredged. If conditions do not permit, the water in the well can be sterilized immediately for temporary use. The well should be dredged a few weeks later.

With the process of clarifying well water: People can use alum (commonly used is aluminum alum) at a dose of 50g/1 cubic meter of water. If the water is very cloudy, you can add up to 100g of alum/1 cubic meter of water. Dissolve all the necessary amount of alum in a water bucket or bucket, and sprinkle the solution evenly into the bottom of the well. Lower the water bucket deep into the well, pull the bucket up strongly about 10 times, then let it sit for about 30 minutes to 1 hour for the sediment to settle, then continue to disinfect.

About well water disinfection: Well water contaminated by floods, in principle, after disinfection, must have a residual chlorine concentration of 0.5 mg to 1 mg per liter of water. Calculate the amount of chloramine B needed for the well based on the required concentration of 10g/1 cubic meter of water. Other chemicals such as 20% lime chloride (13g/1 cubic meter of water) or 70% lime chloride (4g/1 cubic meter of water) can also be used.

Scoop a bucket of water, mix the above chemicals into the water, stir well until dissolved. Pour the bucket of water evenly into the well. Lower the bucket to half the water column in the well, then pull it up and down about 10 times. Use the well water that has been used to sterilize the well, leave it for about 30 minutes, then the water can be used.

One thing to note is that although well water has been disinfected with chloramine as above, the water must be boiled and cooled before drinking. In the absence of chemicals to disinfect well water, you should only eat and drink well water that has been boiled for 10 minutes or more and should not eat raw vegetables washed with unsterilized water.

With well water:The treatment of well water is simpler. People need to pump out all the turbid water and continue pumping for about 15 minutes to remove the water that may be contaminated. Then the well water can be used. People need to pay attention to cleaning the water pump and the well floor./.