Use of sand bags to prevent flooding

[Harry Bloomfield]

One commentator from the EA suggested that sand bags do nothing to prevent flooding, the water is simply slowed down slightly, as passes straight through them, getting filtered as it passes through.

I very much agree with that, so why do they use them?

What does work, is to put the sandbag inside a plastic bag. The weight of the sand allows the bag to conform to what ever surface it is placed upon, the plastic provides the actual seal.

No flooding issues here, but last week I did need to divert a flow of rainwater away from it usual path, to avoid it washing the cement out of some newly laid concrete. Sand in a plastic bag worked fine, to achieve that.

[Bob Minchin]

I heard someone on the radio a week or two ago saying that sandbags were simply a way of letting only filtered water into your home! The other thing mention in the same programme, was that you first sandbag should be shoved in the downstairs loo for similar reasons.

[Harry Bloomfield]

Indeed, they so slow water down, but they are useless where the water table rises above ground level, they can do nothing to help. If that is not the case, then they can be very effective and longer term, if they are combined with a waterproof surface, where the bags just need to act as a wall and provide weight.

What we see is just sand bags being laid in a futile attempt to stop the ingress.

[Nightjar]

They are also quite good at diverting water flow. One house I drive past fairly frequently is on a bend on a hill and is quite a bit lower than the road. That house has a low wall of sandbags across the drive, to ensure that any water keeps flowing down the road and not into the house.

Colin Bignell

[Robin]

Ah but they may have had special tools as in the clip below

I'd love to see that shown so as to see the NSPCC's reaction ;)

[harryagain]

All depends on how fine the sand is. Clay is better but harder to handle/weighs more.

[The Medway Handyman]

I was wondering why they don't use 'water bags'. Made of a flexible rubber type material, the filling is already on site.

[John Williamson]

Because they're light enough to drift with the current. Sand is much heavier than water, so won't float away.

[harryagain]

Such devices exist in the form of long 3' dia. rubber tubes. They are rolled out and filled with water.

[Andy Burns]

Last night I hear it suggested you should flood the inside of your house with clean water to keep the sewage out ... that could end-up leaving you with awkward explanations to the insurance assessor.

[philipuk]

What I wonder, is why if houses must be built in areas likely to flood, they are not built raised such that the ground floor is well above the height any flooding is ever likely to reach. It seems a very simple solution.

Philip

[Jethro_uk]

1) cost 2) not sure about you, but I wouldn't buy a house that advertised it's vulnerability to floods

However, in the current situation, it's debatable as to how much such measures would have helped. From what I can gather, some people have been flooded for weeks. Even if your home was raised sufficient to be habitable, everyday living would prove a challenge.

[Martin Brown]

Some properties are built like that in riverside locations where you go up steps to get into the house and have a partially sunken cellar below the living space that will obviously flood. Some older properties they showed on the news being resupplied by boat were built like that.

The problem at the moment is that major developers are sticking new build on previously open spaces which every local knows *WILL* flood (that is precisely why they were left as open spaces).

The poor incomers don't stand a chance.

[Andrew May]

I was amused by the bod from the NHBC (or whatever) being interviewed on the radio the other day. He was insistent that all these developments were approved by the council and that there had to be a plan to ensure that the development added no more run-off after development than before. Completely missed the point that the problem is the water from elsewhere that floods the site rather than vice-versa. Sadly the interviewer didn't pick this up and let it pass.

[Roger Mills]

That's precisely what they've done with some new houses built near the Avon in Warwickshire recently.

[stuart noble]

Define "ever likely". In some places water levels are already above what anyone living has ever seen.

[Chris J Dixon]

I guess they might still find themselves without working sewers, though that is less hardship than months of builders.

Chris

[Harry Bloomfield]

If the water bag is higher than the water and filled to the brim, they will not float.

[Harry Bloomfield]

In Holland they have a design of house, which when the water rises, the house floats up with the rising water.

[Nightjar]

...

The first house of that type in the UK was recently granted planning permission. I suspect that, after this winter, it would be fairly easy to get such a house approved.

Colin Bignell