Sandbags For Flooding: Do They Work, Where To Get Them And What Works Better
Sandbags can keep shallow water out for a short time, but they leak and are slow to fill and lay. The Environment Agency says sandbags are relatively ineffective compared with purpose-designed flood protection products, and strongly encourages those instead.
If flooding is happening now, put your safety first: follow what to do in a flood, call Floodline on 0345 988 1188 for advice, and 999 if you are in danger. The Environment Agency says: "Sandbags are of no use if your property is already flooded."
What Is A Sandbag?
A sandbag is a sack filled with sand, traditionally used to block doorways, drains and other openings against floodwater. The Environment Agency lists their traditional uses as blocking doorways and drains, weighing down manhole covers and garden furniture, and blocking sink, toilet and bath drains to stop water backing up.
What sandbags have going for them, in the Environment Agency's own guidance:
- They can keep water out for short periods, improved by using plastic sheeting with them.
- They can filter out some muddy sediments in floodwater.
- They are cheap and easy to obtain.
How Does A Sandbag Work?
A sandbag works by forming a heavy, flexible wall that slows water getting past a doorway or opening. It does not seal: the Environment Agency states that Sandbags do seep water even when well-stacked and trodden into place.
The Environment Agency lists the practical problems:
| Problem | Detail |
|---|---|
| Labour | It takes two people to fill them (unless you have a sandbag filling machine) |
| Time | approximately one hour to fill 12 sandbags |
| Handling | They can be difficult to handle, and laying them is time-consuming |
| Water | It is difficult to place sandbags in water, particularly running water |
| Leakage | Sandbags do seep water even when well-stacked and trodden into place |
| Durability | Sacking material is biodegradable and will perish if left in place for a long time |
Its conclusion: we strongly encourage people to use purpose made flood protection products, such as flood boards, non-return valves for plumbing and air brick covers.
What Do Sandbags Cost?
Sandbags are cheap: empty bags and sand can be bought from DIY stores and builders' merchants, and some councils supply them free or for a charge. The real cost is time and the water that still gets through.
How much you need, from the Environment Agency's guidance:
| Quantity | Guidance |
|---|---|
| Bags for one standard door | at least 6 sandbags to keep out 20cm depth of water for a standard door opening |
| Sand per bag | approximately 15kg of sand |
| Filling | Do not fill bags more than half full |
So one door needs roughly 90 kg of sand and two people for about half an hour of filling, before laying.
On price, Checkatrade's cost guide (Last updated: June 2026) puts filled sandbags at around £5 per sandbag, so protecting one door costs around £30 in bags alone — and they are single-use once contaminated by floodwater. A reusable door barrier starts at about £495 and lasts for years, which changes the comparison for anyone who floods more than once. See flood barriers.
Which Sandbags Are Right For Your Property?
Traditional sand-filled hessian or synthetic sacks are the standard option; in an emergency, the Environment Agency suggests alternatives such as pillow cases or refuse sacks and fill them with garden soil. For a home that floods more than once, purpose-made products are the better choice.
| Option | When it makes sense |
|---|---|
| Traditional sandbags | A one-off emergency when nothing else is available |
| Improvised bags | pillow cases or refuse sacks and fill them with garden soil, when sandbags cannot be obtained |
| Purpose-made door barriers and air brick covers | Any home at repeated risk; recommended by the Environment Agency |
How Do You Fit Sandbags?
You fit sandbags by filling them half full, laying them lengthways in overlapping layers like brickwork, and stamping them into place, with heavy-duty plastic sheeting against the wall if you can. Protect every entry point, not only doors, and never build a tall wall without engineering advice.
The Environment Agency's method:
- Fill with two people: one holds the bag open, one fills. Do not fill bags more than half full; you do not need to tie the end.
- Clear the ground where the bags will go.
- Put heavy-duty plastic sheeting between the sandbags and the wall of the house, if you can.
- Lay the bags lengthways, tucking the open end under the filled half, pointing into the direction of water flow.
- Build in layers like a brick wall, each bag overlapping the one below by half, and stamp them firmly into place to close gaps.
- Check other entry points: air bricks, service entry points and cable entries; sandbags will not work there, so use alternatives such as silicone sealant.
- Stay safe. A tall sandbag wall must be designed by engineers; wear gloves and protective footwear, and safety glasses if the sand is dry.
- After the flood, If sandbags are contaminated by flood water, advice should be sought from your local authority environmental health department regarding their safe disposal.
Where to get them. The Environment Agency warns: "Don't assume that the authorities will provide you with sandbags in a flood emergency! It is the responsibility of property owners to take appropriate action to protect their property from flooding." Check your council's sandbag policy before a flood; if it does not supply them, buy empty bags and sand from DIY stores and builders' merchants, remembering that demand can exceed supply when a flood is forecast.
Do Sandbags Reduce Your Insurance Premium?
Sandbags are unlikely to reduce an insurance premium, because they are temporary rather than a certified, installed measure. Insurers can take property flood resilience surveys and certified products into account: the ABI advises owners to Check first if your insurer is able to take surveys into account when assessing whether to insure your property.
Certified, installed measures are what count as evidence; government-funded schemes require that products must have a British Standards Institution (BSI) Kitemark or hold equivalent certification.
What Are The Alternatives To Sandbags?
The alternatives to sandbags are purpose-made flood protection products: door barriers or flood doors, air brick covers or self-closing air bricks, and non-return valves on drains. The Environment Agency names these as the products it strongly encourages instead.
| Alternative | Protects | More |
|---|---|---|
| Door barriers and flood doors | Doorways | Flood barriers |
| Air brick covers and self-closing air bricks | Air bricks and underfloor voids | Anti-flood air bricks |
| Non-return valves | Drains, toilets and sinks | Property flood resilience |
| Sump and pump | Cellars, basements, groundwater | Sump pumps |
If your home has flooded, you may be able to get help with these through a grant or your insurer; see property flood resilience grant.
Sources (Verified 17 Sep 2026)
| Claim | Source |
|---|---|
| All sandbag uses, limits, quantities, filling, laying, safety, supply, disposal, alternatives | Environment Agency, Sandbags and how to use them properly for flood protection (March 2009) |
| Councils vary in supplying sandbags | Hampshire County Council, Who can provide sandbags |
| Surveys | ABI, Accessing flood insurance |
| Kitemark | Environment Agency, FloodReady review |
Frequently Asked Questions
Do Sandbags Actually Work?
Sandbags can hold back shallow water for a short time, but they seep even when well laid. The Environment Agency describes them as relatively ineffective compared with purpose-designed flood protection products.
How Many Sandbags Do I Need For A Door?
The Environment Agency advises at least 6 sandbags to keep out 20 cm of water at a standard door opening, with each bag needing about 15 kg of sand and filled no more than half full.
Does The Council Provide Sandbags?
Some councils keep sandbags for emergencies, often prioritised or charged for, and many do not supply them to protect private homes. The Environment Agency advises checking your council's policy before a flood.
What Can I Use Instead Of Sandbags In An Emergency?
In an emergency, the Environment Agency suggests pillow cases or refuse sacks filled with garden soil. For lasting protection, purpose-made door barriers, air brick covers and non-return valves work better.