How to Protect Your Home from Floods​

Created By RISC | 1 year ago

Last modified date : 1 year ago

Flooding inevitably threatens many people during the rainy season.​

But we can protect ourselves by developing and managing flood prevention systems. Many aspects must be considered to design the most appropriate and efficient system:

- Risk assessment:  Evaluating dangers in each location, such as water sources that may be vulnerable to flooding, storm risks, and other potential variables to determine the required level for a house and its inside space based on historical water level survey data going back 10 years.​
- Design of the drainage system: A suitable drainage system must be able to handle the volume of water during severe rain or flooding. If the residence is below the public drainage level, this system may also incorporate wastewater pumping equipment in addition to gutters and drainpipes.​
- Preventing water incursion into your property: If your home is beneath the public drainage system, water may enter through pipes. During the rainy season, we may need to prepare waterproof material to prevent flood waters from entering the structure through gaps or fractures, such as concrete sealer and sandbags filling manholes in the drainage system.​
- Building defenses and walls: Building flood protection such as walls or other structures. Even though it is the final stage, it is the first step that must be avoided: building a wall or designing a door that can be utilized with a basic water protection device, such as a flood prevention door.​

You might wonder why there’s still indoor flooding even if a wall or sandbag are in place and sealer has been used to keep water from leaking into the house. ​

That's because key aspects are often overlooked, resulting in a failure to prevent water from entering the house from outside, namely the sewerage system."

Wastewater normally exits the building via pipes into the lower public sewer. During a flood, however, the water level in the public sewer pipe will be higher than the sewage pipe level. Outside water therefore flows back into the house. So be ready for a future flood with a system to prevent water running back into the sewer pipe. ​

A "backflow prevention system" stops water returning to the house via the sewage or plumbing pipes. The system can be utilized in situations where we can keep water from entering the house by other methods (when the outside flood level is about 50-60 cm). The system protection directs higher water levels back into the house via the sewer system. The size of the water backflow prevention system depends on the size and volume of water utilized in each dwelling. A house with 3 bedrooms and 2 bathrooms, for example, should construct a wastewater tank that is at least 50 x 50 x 50 cm (width x length x depth) and has enough space to install a water pump or divo pump. Pumps need electricity so electrical wiring should be run into the home to make it easier to turn the system on and off. A 1.5-inch-diameter pump pipe can connect to a PVC pipe or rubber hose to pump outside the building or outside the gate. A water valve (sluice gate or butterfly valve size 6 inches) or a set of short pipes covering plate to the sewerage pipe can drain water from the wastewater pond to the public drainpipe. The valve should be fitted and closed if the water level outside is higher and opened if the water level inside is higher. ​

After constructing the flood protection system, regular maintenance is required prior to the rainy season. If a pumping system is installed, the machine itself must be inspected or get the fuel ready if it is a pump that uses an electrical system, checking for damage to the electrical wires. Various protective equipment should be kept on hand at all times so it can be used quickly and safely in an emergency.​

There should also be an emergency response plan for flooding. Being prepared can help to avoid panic when a flood occurs, including reviewing findings after the storm to see whether the flood protection system is effective or needs to be enhanced.​

Story by Montri Phulanku, Senior Research Engineer, Well-Being Research Integration and Building Infrastructure Specialist, RISC