Slightly Anxious about rising water levels

We will now focus on how to prepare your property for a flood with the understanding that this is simply to minimise the damage to it, not to act as a place of shelter for you and yours. We want you and your household as far away well before the defences you have employed get tested. We cannot but keep repeating – the right course of action is to get everyone to leave as quickly as possible, well supplied and knowing where they are going. Your property’s flood defences should be in place well before the call for evacuation comes. This is the key, long term preparation as what you need to do will take time. This means structural work to your home plus the purchasing of flood defence equipment which you install when the first flood warning is raised.

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We need to point out that most properties in the UK are just not built to withstand flood water and over a depth of 2 feet there is serious risk of structural damage. So, if you do want your property to have the best chance of survival should the worst happen, then you will have to pay for significant engineering works.

This is the work you will need doing to your property for the long-term defence against flooding:

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• Garden – have the minimum of paving as rainwater needs to be allowed to drain into the soil. Pathways should be gravel and driveways have a permeable surface. Wherever possible water should be allowed to drain away, either downwards and/or off the property. As you will have read in our article; ‘What to do when the water is turned off’ having water butts to collect rainwater can be very useful, they also help prevent flooding, especially if you can direct their run off away from the property.

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• Below Ground – have sump pumps installed in/above sump pits that are dug a few feet below your property and garage or installed in the cellar. Flood water will seep in and be pumped out by the sump pumps and then directed away from the property. Installation can cost between £1,000 and £5,000 per pump and you may need more than one dependent on your property’s size.

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• Non-return valves in sewer pipes – flood water can enter the sewage system and bring with it sewage, dirty water and stormwater, this can then force its way into your house through toilets, sinks, showers, and floor drains. To prevent this you need a non-return valve, also called a backflow valve or backwater valve, installed in your sewer pipe. This will allow waste water to flow out of your property but stops sewage or floodwater flowing back in. The cost for this is obviously dependent on how much work is needed, such as excavation, to install it – budget between £3,000 and £10,000. The valves will need regular maintenance to prevent blockage and be aware that if its in operation, you can't use the toilet or taps. But as you will have evacuated the property this shouldn’t be a problem. This is arguably, one of the most useful bits of flood prevention kit.

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• Raised electrical sockets – one of the biggest cost in repairing flood damage is what the flood water does to the electrics of your house by seeping into the electrical sockets which are usually located at just above floor level. The water can not only destroy the electrical circuits thus meaning a complete rewire and rebuild but it also means there is a severe risk of electrocution while the property remains wet. The simple solution is to just raise the electrical sockets to a height above what previous floods have shown to be the level water reaches. The cost of this is dependent on the type and size of house you have and therefore varies between £1,000-£15,000. Having functioning electricity aids the recovery post flooding as it provides lighting and can power dehumidifiers and pumps.

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• Raised electrically linked equipment – in the same vein, all equipment that plugs into the mains should be raised above the expected flood level. This means light switches, consumer unit / fuse box, wiring junctions, internet/network equipment, alarms, smart home controls, boiler controls and EV charger controls and all need raising. The cost of this including protected circuits and flood-resilient routing can be between £4,000 and £8,000.

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• Ensure your TV is wall mounted – cost part of above

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• Separate electrical circuits between floors – this isolates the lower floors so if flooded, the upper floors, if untouched, should remain powered. This cost will hopefully be included in the above.

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• Hardening the ground floor – this means replacing carpets with tiles and waterproof grouting as tiles are waterproof and carpets act like a sponge. This is considered one of the better ways of increasing flood resilience, but can get expensive dependent on the subfloor conditions, estimated costs of between £6,000 and £12,000. Expensive but well worth it if there is regular flooding.

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• Sacrificial lower-wall materials – there is nothing you can do to defend your property 100% against flooding. The water volume and pressure is too much, so what you do is work with it. This means sacrificial lower-wall materials, you just accept that the lower wall will get ruined, so it’s as cheap and disposable as you can put up with (e.g. moisture-resistant plasterboard, cement board or lime plaster). After the flood you can just remove it, thus not having the cost of a full rebuild, dry out the structure and replace.

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• Cavity drainage systems - behind your removable skirting you can have a perimeter drainage channel that directs the water coming in towards a sump pit and pump to be pumped away. This is considered belt and braces by many and costs accordingly, between £2,000 and £8,000

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• Self-closing airbricks – many UK houses have airbricks at ground level to ventilate floors and wall cavities. They are very important as they prevent condensation, timber rot and mould growth. Self-closing ones come either with a float-based system or a mechanical flap that closes when water rises, sealing the brick completely. They can cost up to £300 each and installation can be up to £300 as well. A small house will usually have between 4 -8, thus a budget of £2,000 - £4,000. See airbrick covers below for a cheaper, inferior option.

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• Bottom 3 steps of your internal stairs made of concrete – this is a luxury but is based on the fact that in any flood the lower steps of your internal stairs, which are usually made of wood, are always going to get the most sustained damage and may very well force you to have the whole staircase replaced at quite some cost. By having the bottom 3 steps made of concrete, even if it is masked with tiles or stone finishes, means that after the flood all you have to do is pressure wash, disinfect and dry rather than rip out and replace. Cost for this can be between £1,000 and £8,000 dependent on the amount of work needed as you may need a whole new staircase.

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As you can see, if you want to make the kind of alterations to your home to make it resilient to repeated flooding events, you will have to spend tens of thousands of pounds. It really only makes monetary sense if you are planning a major refurbishment and get everything done at once to make some savings that way. The alternative is taking a massive gamble and hoping that with some short-term solutions will prevent the worst happening, just remember that the stakes at play here are your actual property. If it suffers too much flood damage sometimes it’s just cheaper to knock it down and start again.

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At Slightly Anxious, we heard a mischievous story that we must stress we can't authenticate. A couple purchased a property in a known flood plain, got as much insurance as they could, bought temporary flood defences and are now waiting for the next inundation. If the flooding is severe and consequent damage to the property significant, they will just have it knocked down and using the insurance money rebuild featuring all of the above flood resilience features as they are the cheapest to implement at the new build stage. We are not sure if this is the best way to deal with flooding, we kind of think the question should be more about why you are planning to buy in a location known for flooding? And if you are, surely you should budget for the needed flood resilience refurbishments in the first place.