Water can appear in a home within minutes. All it takes is a sudden downpour for the level in the lowest room to rise faster than you can carry your more valuable belongings upstairs. A flooded basement or garage after heavy rainfall is nevertheless a situation you can bring under control if you follow the right order of operations: safety first, then pumping out the water with the appropriate pump, and drying everything out at the end. Based on our experience as a pump manufacturer, we know that most damage occurs not during the flooding itself, but afterward, when moisture has time to penetrate the walls and floors.
In this guide, we explain what to do in the event of flooding, step by step: what to do in the first few minutes, which pump to use depending on whether the water is clean, sandy, or mixed with sewage, how to dry the room afterward, and how to protect your home so that the next downpour does not end the same way.
Water in a basement, house, or garage after heavy rainfall. Where to start
Before reaching for the pump, take a moment to do three things that determine both safety and whether it is appropriate to start pumping at all. This order is not accidental.
Step 1. Switch off the power before entering the water
A flooded room with a live electrical installation poses a real risk to life. Before entering the water, switch off the power to the flooded area at the electrical panel. If the panel itself is in the flooded room and cannot be reached safely, do not enter the water and call the electrical emergency service. Do not approach outlets or appliances standing in the water. Power the pump from an outlet outside the flooded area, preferably from a circuit protected by a residual-current device, and keep extension cords and connections above the water level. This is the basic precaution on which your safety may depend.
Step 2. Determine where the water is coming from and what kind it is
The type of water determines which pump to choose and how to clean up afterward. Rainwater and groundwater may be relatively clean, although after heavy rainfall they often carry sand and silt washed in from the surrounding area. Water backing up from the sewer is sewage and must be treated as a biological hazard. Check whether the water is cloudy and sandy, whether it has a noticeable sewage odor, and whether the level is still rising or has stabilized. This determines which type of pump you should use.
Step 3. Check whether it is safe to start pumping
If the flooding is caused by a flood or a very high groundwater level, and water is also still present outside the building, do not empty the basement too quickly. When the water level outside is high but the interior is dried rapidly, significant pressure from the surrounding soil and water below begins to act on the walls and floor, risking cracks or the floor being pushed up and structural damage.
How can you assess this level if it cannot be seen directly? The simplest way is to observe the water itself. Pump out some of the water and observe: if the level in the basement quickly returns or rises on its own after pumping, this indicates that groundwater is pressing in from outside and remains high. The surroundings of the building are another clue, because standing water in the garden, around the foundations, or at street level indicates a high groundwater level. A well or inspection chamber on the property can also provide a useful reference point; its water level roughly corresponds to the groundwater level. As long as you see these signs, lower the level in stages: pump out some water, wait, check how much has returned, and continue as the water around the building recedes.
The same caution applies to empty underground tanks, such as septic tanks or rainwater tanks. When groundwater levels are high, an empty tank may be pushed upward, so do not empty it preemptively during flooding.
Step 4. Take photographs before you start pumping
If you intend to claim compensation, this is the moment when your most important evidence is created. The insurer will assess the damage based on what you show them, and the visible waterline is the strongest evidence of the extent and height of the flooding—something that can no longer be reconstructed after the water has been pumped out. Therefore, before disturbing the water, take photographs and videos showing how high it reaches, preferably with the date captured.
If there may be live electricity in the room or you are not certain that the power has been switched off, do not enter. Instead, take photographs from a safe distance—from the doorway, the stairs, or through a window. Continue documenting the situation at every stage as the water level drops, until the premises have been fully dried.
When you can manage on your own and when to call for help
A homeowner can deal with minor flooding involving relatively clean water independently, provided the pump is working and the water can be safely discharged outside. Professional help is advisable when there is a large amount of water, when it is mixed with sewage or chemicals, or when the water level has reached electrical installations and they cannot be safely disconnected.
The fire brigade primarily intervenes where there is a real threat to life, health, or property on a larger scale. You should report the incident by calling 998 or 112, and the dispatcher decides whether to send a crew. In the case of minor flooding in a basement on private premises, the response may be limited or referred to specialist services and companies. Rules and local practices may vary, so if in doubt, describe the situation to the dispatcher and follow their decision.
Which pump should you use to pump out water? Choosing one based on the type of water
The key rule is simple: choose the pump for the type of water, not the other way around. A pump designed for clean water will wear out quickly if placed in sandy water, while a pump for light contamination will not cope with fibrous matter from wastewater. Below, we distinguish three typical situations.
Relatively clean or lightly contaminated water
For rainwater and groundwater without abrasive elements, submersible pumps with a small passage and the ability to drain water to a low level are suitable. In our range, these include, for example, pumps from the IC and DRAIN series. The IC 400 model (0.4 kW, 230 V) achieves a head of up to 5 m and a capacity of up to 158 l/min. Its practical feature is two interchangeable bases that allow you to adjust the suction height to the current water level. The DRAIN 400 pump (0.4 kW, 230 V) operates in both automatic and manual mode and allows contaminants up to 35 mm in size to pass through, while the more powerful DRAIN 750 raises water up to 8 m. When you need higher capacity without a float, for example, for supervised operation, the ISD 40-370 is a suitable choice, with a head of up to 9 m and a capacity of up to 250 l/min. You can find the full selection in the clean and lightly contaminated water pumps category.
Water containing sand, silt, and sludge
After heavy rain, water very often carries sand and silt washed from a yard or construction site, and this is the most deceptive case. Sand grains wear down the impeller and mechanical seal of a standard pump, causing it to fail much sooner than its power rating would suggest. That is why, for sandy and muddy water, you should not use a clean-water pump, but a sludge pump with an impeller made of cast iron or an abrasion-resistant alloy; its cooling jacket allows it to operate without being fully submerged. Three things matter when choosing one. The first is the impeller’s resistance to abrasion, which you will find, for example, in the KBFU 50-0,45 model (0.45 kW, 230 V), equipped with a float and designed for water containing sand, draining it down to approximately 60 mm. The second is the minimum pumping level when you want to dry the bottom completely; here, the KBFU 50-0,80 (0.75 kW, 230 V) helps, with a minimum level of 50 mm. The third is the control method, because for unattended operation, an automatic pump with a level sensor is more convenient, such as the KBFU AUTO 50-0,48 (0.48 kW, 230 V). Thanks to its wide impeller passage, it tolerates fine sediment, with a capacity of up to 240 l/min and a head of up to 11.5 m. The specific model is selected based on the required head and capacity, and if you have any doubts, we will be happy to advise you. You can find a full overview of these devices in the drainage and excavation pumps category.
Water mixed with sewage
If water has backed up from the sewer and contains fibrous matter or feces, a standard clean-water pump will quickly become clogged. In this case, you need a pump with a large free passage or a grinder pump that breaks up contaminants before pumping them onward. The WQZ 50-2200 (2.2 kW, 230 V) is ideal for this task, featuring a grinder and float switch, a lifting height of up to 23 m, and a flow rate of up to 600 l/min. You can find a complete overview of solutions for dirty water and sewage in the sewage and septic tank pumps category. It is worth remembering that we discuss the differences between a standard submersible pump and a grinder pump in more detail in a separate guide dedicated to choosing these devices.
To what level will the pump drain the water
Every submersible pump has a specified minimum pumping level, below which it would draw in air. In practice, this means that a layer of water remains at the bottom—for example, approximately 50 mm in the case of the KBFU 50-0,80 model. The last few millimeters are removed with a pump designed for low-level drainage or finished manually. Important operating note: at a very low water level, the float switch is no longer useful because there is nothing left to lift it, so the pump operates in manual mode under supervision. You must monitor the level and switch off the device before it draws in air, as dry running may damage it.
How to choose the lifting height
This is the question on which the effectiveness of the entire operation depends. The lifting height you actually need is the difference in level between the water surface and the discharge point outside, plus losses caused by the hose, its length, and the elbows. The maximum flow rate given in specifications applies to zero lifting height, so the higher and farther the water has to be pumped, the lower the actual flow rate. If the water needs to reach far from the building or significantly above basement level, choose a model with additional lifting capacity rather than one whose maximum barely matches your required height. Our calculators and selection guides can be helpful when choosing the parameters, and if you have any doubts, we will be happy to help you select the right device.
When the power goes out
Heavy rain and flooding go hand in hand with power outages. If there is no electricity during flooding, the solution is a gasoline-powered pump, also known as a motor pump. Remember the safety rule: the gasoline-powered pump itself must operate exclusively outdoors because of the exhaust fumes; only the suction hose should be brought indoors. We have collected gasoline-powered models in the gasoline-powered pumps category.
What to do after flooding – drying and hygiene
Pumping out the water is only half the job, because the real problem is the moisture that penetrates walls, floors, and plaster, resulting in mold and a characteristic odor after a few days. Simply wiping surfaces dry is not enough, because water soaks deep into porous materials and evaporates from them over the course of weeks. That is why drying should be treated as a separate stage carried out in several steps.
Start by removing everything that has absorbed water and cannot be effectively dried: cardboard, composite-board furniture, carpeting, and insulation materials. Wash hard surfaces and remove any remaining silt from them before it starts to dry, as it will be harder to remove later. Only a clean and emptied room is worth drying.
The next step is removing moisture from the air and structural elements. In practice, two things are combined: ventilation, which carries moist air outside, and forced drying. Simply opening the windows helps only when the outdoor air is drier than the air in the basement, which often is not the case after heavy rain when humidity is high; a draft can even blow moisture inside. A condensing dehumidifier is more effective: it condenses water from the air and allows you to control humidity, supported by air circulation from a fan when necessary. In colder conditions, a desiccant dehumidifier works better. This is a slow process: bringing a damp basement to a dry state usually takes anywhere from a dozen or so days to several weeks, depending on how deeply the water has penetrated the walls.
It is worth monitoring progress rather than relying on impressions. You can check the air humidity with a simple hygrometer and the condition of the walls with a moisture meter; only when these readings have stabilized does it make sense to consider finishing work. Painting too early or laying flooring on a damp substrate leads to blistering, plaster flaking, and mold underneath.
If the water was mixed with sewage, disinfection must be carried out before drying. Treat such water as a biological hazard: work in gloves and other protective equipment, and disinfect surfaces with a biocidal product after washing them. In the event of heavy fecal contamination, it is more sensible to have the disinfection carried out by a specialist company equipped, among other things, for ozonation or fogging. It is best to consult a specialist on the selection of specific methods and products, as this depends on the extent and type of contamination.
Insurance: flooding vs. flood
The scope of coverage depends on the specific policy and is often more extensive today than one might expect. In many contracts, flooding, flood, torrential rain, waterlogging, water backing up from the sewer system, and groundwater pressure are separately defined risks, each of which may or may not be covered, sometimes only after purchasing an extension and with a separate liability limit. Flood, understood as rising water or rapid runoff after heavy rain, is often such a paid extension and may also be subject to a waiting period counted from the conclusion of the contract. There are also exclusions that can determine whether a claim is paid, such as failure to carry out maintenance or the lack of required protection. Therefore, do not rely on general rules; check how the event is defined and covered in the general terms and conditions of your policy, and if in doubt, ask your insurer or agent directly.
Who is responsible for sewer backflow?
This question comes up after every major downpour, and there is no single answer. As a rule, the obligation to protect drains located below the so-called flood level rests with the property owner, as follows from the technical and construction regulations. Who ultimately covers the damage, however, depends on who is responsible for the relevant section of the network, and the outcome may vary depending on the facts of the case. In practice, it is worth consulting the regulations on water supply and wastewater disposal applicable to the local water utility, and seeking professional assistance in the event of a dispute. Regardless of liability issues, the most effective protection against sewer backflow remains proper installation protection.
How to protect your home from another flood
Responding to flooding is important, but the best investment is preventing it from happening again in the future.
Backflow preventer and pumping station
Drains located below the flood level should be protected against the backflow of sewage. This requirement follows from the regulation on the technical conditions buildings should meet. Depending on the installation layout, a backflow preventer or a pumping station is used to pump sewage above the level from which it could flow back. It is worth taking this seriously for practical reasons as well, because an insurer may consider the lack of the required protection grounds for refusing to pay compensation for flood damage. Solutions for permanent installation in rooms below the sewer level include, among others, underfloor pumping stations, which we describe in our product range.
Sump with pump, float switch, and flood sensor
For properties that are regularly flooded, a drainage sump with a pump equipped with a float switch is a good solution. The pump starts automatically when the water in the sump rises to the set level and switches off after the water has been discharged, allowing it to operate without constant supervision. A flood sensor with an alarm is a useful addition, warning you before water spreads through the room. Control and safety components, including float switches and controllers, are collected in the control and safety category. It is also worth considering a backup power supply, as flooding often coincides with a power outage.
Drainage, waterproofing, and rainwater management
Across the entire property, risks can be reduced with perimeter drainage that carries water away from the foundations, watertight waterproofing of basement walls, and well-planned rainwater management—for example, directing it to a retention tank instead of toward the building walls. These are long-term investments, but when flooding recurs, they pay for themselves sooner than you might expect.
In summary, the correct order of actions is to prioritize safety and switch off the power, then choose a pump suited to the actual type of water, thoroughly dry the area, and finally permanently protect the installation and building. If you need help choosing a pump for a specific situation, contact us—we will be happy to advise you. You can find a full overview of the equipment in the submersible pumps category.
Dambat, a trusted manufacturer of pumps and water-management equipment with quality certifications.
Frequently Asked Questions (FAQ)
How do you pump water out of a flooded basement?
First, switch off the power to the flooded area at the electrical panel, and only then place a submersible pump suited to the type of water in the water and discharge it outside the building using a hose. For clean water, use a low-level drainage pump; for water containing sand, use a sludge pump; and for sewage, use a pump with a grinder. Choose the head with a reserve relative to the discharge point, because a long hose and elevation reduce the actual flow rate.
Which pump is best for a flooded basement or garage after a downpour?
The best pump for a flooded basement is one that suits the type of water, not simply the most powerful one. For relatively clean water, low-level drainage submersible pumps such as IC 400 or DRAIN 400 work well. For water containing sand and sludge, you need a sludge pump from the IBO KBFU series, while for water mixed with sewage, use a pump with a large free passage or a grinder, such as the WQZ 50-2200.
Which pump should you choose for water containing sand after a downpour?
For water containing sand, use a sludge pump with an abrasion-resistant impeller and a cooling jacket, not an ordinary clean-water pump. Sand wears down the impeller and seal of a standard pump, causing it to fail much sooner. The IBO KBFU series models in our range are suitable, such as the KBFU 50-0,45 or the maintenance-free KBFU AUTO 50-0,48.
Can water be pumped out of a basement with a vacuum cleaner?
Water can only be collected with a vacuum cleaner designed for wet operation, and only when there is a small amount, such as residue on the floor. An ordinary household vacuum cleaner is unsuitable and risks electric shock and damage to the device. For larger amounts of water, the proper tool is a submersible pump, which will pump it outside through a hose.
To what level will a submersible pump drain water?
Every pump has a minimum pumping level below which it would suck in air, so a thin layer of water remains on the floor. For example, the KBFU 50-0,80 model removes water down to a level of 50 mm. The last few millimeters can be removed with a low-level drainage pump or manually, bearing in mind that the float switch will not work at such a low level and the pump must be monitored.
Will the fire service pump water out of a basement?
The fire service primarily responds to a genuine threat to life, health, or property on a larger scale; reports should be made by calling 998 or 112. The duty officer decides whether to dispatch a crew, and in the case of minor flooding, the response may be limited or referred to specialist companies. Procedures and local practice vary, so it is best to describe the situation to the duty officer.
Who is responsible for basement flooding caused by a sewer backup?
As a rule, the property owner is responsible for securing drains located below the flood level. Who covers the damage depends on who is responsible for the relevant section of the network, and decisions can vary. It is worth consulting the local utility’s regulations on water supply and sewage disposal, and seeking help from a specialist in the event of a dispute.
What is the difference between water damage and flooding in insurance?
In insurance policies, water damage and flooding are usually two different risks. Water damage, for example from a plumbing failure or a sewer backup, may be covered under the basic policy, whereas flooding is more often a separate, paid extension with a waiting period. Definitions vary between insurers, so the wording of your policy’s general terms and conditions is decisive.
