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The Science Behind Sandbags for Flooding: A Sinking Solution

In February 2024, the EU’s climate service reported that global warming has exceeded 1.5C across an entire year. With this, comes a huge risk of increased flooding worldwide. So, what can we do to protect the people around us and our environment from these natural disasters? Predominantly, we need effective flood defence measures in place that offer rapid response times and durability. The question is, are traditional flood defence measures like sandbags fit for the job?

How effective are sandbags for flooding?

Despite their sturdy appearance, sandbags have inherent structural limitations that allow water to seep through the gaps between bags when stacked together. With their effectiveness dependent on proper filling and stacking, a task that is easier said than done especially in emergency conditions, sandbags have structural weaknesses that can compromise an entire flood defence system. In many cases, floodwaters find their way around or even under sandbag barriers - reducing their reliability and overwhelming communities in their fight against floods.


Even when properly filled and stacked, sandbags for flooding require constant monitoring and maintenance, especially during prolonged flooding events. As the sandbags become saturated, their ability to hold back water diminishes and frequent replacements are needed. These can be both slow to deploy and time-consuming to lay, increasing the risk of water breaching the area and causing lasting damage in the meantime. Demanding continuous labour and increasing costs due to non-reusability, sandbags provide a temporary solution and are best suited for low-flow protection against flooding.

How do sandbags impact our environment?

Aside from the financial cost of replacing saturated sandbags, there is an environmental cost to consider as well. Sandbags for flooding are typically made from woven polypropylene or burlap - non-biodegradable materials that are far from eco-friendly and can contaminate local ecosystems. What’s more, taking sand from certain environments can contribute to bank erosion and loss of habitat. The overall production process for sandbags involves the extraction of raw materials and significant energy consumption which contributes to pollution and the emission of greenhouse gas. Although relatively small in size, each bag represents a cumulative environmental cost that can’t be ignored. 

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Once produced, sandbags are often transported to flood-prone zones via heavy-duty vehicles that have a considerable carbon footprint, especially if emergency responses are involved. Additional machinery is then required once sandbags become saturated and more need to be deployed. After the floodwaters recede, the challenge is then around disposing of the used sandbags safely and properly. Used sandbags for flooding can often become contaminated with pollutants from the floodwater and can’t be simply discarded or reused without the correct treatment. Any remnants of sand and plastic then contribute to long-term environmental degradation - leaving behind a legacy of pollution.

What can be used instead of sandbags?

With the risks of floods on the rise, investing in effective, long-term flood defence solutions has never been more important. Innovative and eco-friendly solutions including modular flood barriers are better alternatives to sandbags when it comes to flood protection. Compared with sandbags for flooding, flood barriers are easy to assemble and can be deployed within minutes. This makes them versatile solutions that can be used as temporary or permanent fixtures to address flash floods quickly and effectively. Flood barriers often come in varying weights and sizes to suit your flood management needs while their overall slim design ensures minimal storage requirements so they can be safely packed away for a rainy day.

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Together with the pioneering Fluvial Innovations, we are committed to developing robust, tailored flood defence solutions that are fully compliant with European standards. Using award-winning, technology-led products, we provide a bespoke experience for optimal safety, quality and sustainability. When it comes to materials, our flood barriers are made predominantly from low-density polyethylene or galvanised steel, making these solutions reusable, recyclable and cost-effective across home, council and commercial use.

Explore how our innovative flood barriers enabled the Environmental Agency (EA) to create safer spaces after the 2007 floods.

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Flood defence comparison: Sandbags vs flood barriers


Flood barriers



Often non-reusable


Regular maintenance and labour demands

One-time assembly and pack away

Cumulative replacement costs

One initial cost

Non-biodegradable materials

Recyclable materials 

Timely setup to stack properly

Deployed within minutes

Unsuitable for severe flooding

Suitable for all flood types

Investing in innovative flood defence

While sandbags for flooding have been a traditional go-to for flood defence, they are far from the best solution. Their environmental drawbacks and structural limitations highlight the need for more practical and efficient alternatives. Investing in long-term flood defences like flood barriers can not only help to protect people and your property more effectively but can also save you thousands in the process while reducing our ecological footprint. 

Download our Flood Barriers Solution Catalogue to explore the latest in effective flood defence towards a safer, more sustainable future.