Flood resilience expert challenges the use of sandbags in flood prevention

Flood resilience campaigner and consumer champion, Mary Long-Dhonau OBE, has launched a campaign that challenges the use of sandbags as part of a strategy for flood prevention or flood risk management.

While sandbags have traditionally been handed out when flooding is imminent, research shows they are often ineffective and provide minimal flood resistence – and in some cases create additional issues.  Mary explains:

“In a recent test at an accredited British Standard Institute testing tank, four sandbags placed in front of a household door failed after just 59 seconds of the water being turned on, while 10 sandbags held water back for just over two minutes.

“Furthermore, the sand that escaped from the bag badly blocked the sump pump used to drain the water out of the testing tank. This also happens in real flood conditions and sand often collects in drains, rendering them inefficient come the next heavy rainfall. Sandbags do more harm than good and it frustrates and upsets me to see them continually being used as a go-to solution when they simply don’t work.”

For over 20 years, Mary – who is affectionately known as Mary Queen of Floods – has been supporting communities that are at risk of flooding by providing guidance in relation to modern Property Flood Resilience measures and adaptations that can instead be made to lessen the impact of flood water.

Mary, who is director of MDA Flood Resilience Consultants, lead of the Know Your Flood Risk Campaign and PFR advisor for the Ox-Cam PFR Pathfinder Project, stands firm in her view that sandbags should not be considered a 21st century solution to flooding:

“Whenever a flood is imminent, everyone at risk calls for the humble, inefficient and environmentally-unfriendly sandbag, which I consider to be no more than a ‘comfort blanket’ when a flood emergency happens.”


Sir Michael Pitt’s review into the extensive floods of 2007 was unable to find any considerable evidence that sandbags were particularly effective in safeguarding households. Nevertheless, 15 years on and sandbags are still widely regarded as an important focus for community action.

Concludes Mary: “The general provision of sandbags should be phased out in favour of proven products, such as kite-marked flood boards, air brick covers and other forms of temporary defence. Sandbags do little more than filter flood water. They are time consuming to fill and put in situ, are not easy to store, quickly become contaminated by filthy flood water rendering them completely unusable, and are a challenge to dispose of.

“Whilst investment is needed in temporary barriers, the risk of flooding is only increasing and therefore it is time and money well spent; now is the time for people to really see just how ineffective sandbags truly are and to ban them in favour of proven, modern alternatives.”

Property Flood Resilience measures include non-return vales, wall membrane systems with accompanying sump pumps, flooring, wall coverings, alternative skirting boards, waterproof plaster and insulation, self-closing air bricks, periscope covers, recoverable kitchens and flood barriers and doors – including those suitable for listed buildings.

To learn more about Property Flood Resilience, Mary Long-Dhonau has co-authored several guides including the Homeowners Guide to Flood Resilience and a Property Flood Resilience eBook. Both are free and available to download here: https://marydhonau.com/.


About Mary Long-Dhonau OBE:

Having been flooded herself on many occasions, Mary has become a consumer champion for flood awareness and property flood resilience. She has extensive experience in supporting and advising the victims of flooding during their recovery and is vocally passionate regarding raising awareness of Flood Risk.

Mary is the co-author of the Homeowners Guide to Flood Resilience, the Business Guide to Flood Resilience, the Homeowners Guide to Flood Recovery and has recently published an Ebook ‘’Property Flood Resilience: stories from homes and businesses who have made adaptations to help them recover more quickly after a flood”. She was awarded an OBE for Services to the Environment in the Queen’s Birthday Honours list in 2009.

In December 2014 Mary was awarded an HonRICS, in recognition of her high profile standing up for the public interest regarding flooding. She was also given the ‘Voice of the Customer ‘award and the CII Public Interest Awards 2015, an Hon.DSc from the University of the West of England in July 2015 and was made an HonFCIWEM in 2017

Having been flooded herself on many occasions, Mary has extensive personal experience and is very passionate about advising victims of flooding during their recovery, offering advice in relation to ‘building back better’.

Website: https://marydhonau.com/