Filled or Empty Sandbags: Which Is Better for Flood Preparation?

When flooding is possible, waiting until water is approaching the property is rarely the best time to start looking for sandbags. Demand can rise quickly during periods of heavy rain, and some councils do not provide bags directly to individual homes or businesses.

Preparing in advance leaves you with two main options: storing empty sandbags and filling them when required, or keeping a supply of bags that have already been filled.

Both approaches can be useful. Filled sandbags provide a faster response, while empty bags are considerably easier to store and transport. The right choice depends on the flood risk, available storage, access to filling material and how quickly people can prepare and position the bags.

Martins Mill Packaging supplies 33 × 70 cm woven polypropylene sandbags with tie strings for flood preparation, water diversion, ballast and general site use.

The Short Answer

Filled sandbags may be the better choice when immediate deployment is the priority and there is suitable space to store them close to the area at risk.

Empty sandbags are usually more practical for planned preparation. They take up less room, are easier to move and can be stored until a flood warning or period of severe weather makes filling them necessary.

Empty bags only provide useful preparation when the rest of the plan is already in place. This means having suitable filling material, tools, people and enough time to prepare them before floodwater reaches the property.

Filled and Empty Sandbags Compared

The following comparison covers the main practical differences:

• Speed: Filled bags can be placed immediately, while empty bags must be prepared first.
• Storage: Empty bags require much less space than filled ones.
• Handling: Empty bags are light to transport, but become heavy once filled.
• Preparation: Empty bags require filling material, shovels and sufficient labour.
• Flexibility: Empty bags can be filled only when needed and used for other suitable ballast or site tasks.
• Inspection: Stored filled bags must be checked for damage, deterioration and contamination before use.

Neither option is automatically better in every situation. The most important consideration is whether the bags can be prepared and positioned safely before water arrives.

When Filled Sandbags May Be More Practical

Filled sandbags can save time when a flood warning has been issued or when a property is vulnerable to fast-developing surface-water flooding.

They may be useful for:

• Properties where water can rise with little warning
• Businesses that need to protect low doorways or loading areas quickly
• Sites without immediate access to loose sand or filling equipment
• People who would struggle to fill a large number of bags during an emergency
• Locations with secure, sheltered storage close to vulnerable openings

The principal advantage is that they are ready to position. Staff or residents can concentrate on protecting the most vulnerable areas rather than filling bags while weather conditions worsen.

The Drawbacks of Storing Filled Bags

Once filled, sandbags become heavy and bulky. A supply large enough to protect several openings can occupy considerable storage space and involve a significant amount of manual handling.

Filled bags should be kept somewhere:

• Dry and protected from standing water
• Sheltered from prolonged sunlight and weather exposure
• Accessible during an emergency
• Away from chemicals, oils and other contaminants
• Close enough to the vulnerable area to avoid unnecessary carrying

Do not place them where other equipment, pallets or stock will block access. Bags stored outside should be inspected regularly because weather exposure and accidental damage can weaken them.

The filling material may also settle or harden over time. Every bag should therefore be checked before relying on it during a flood.

When Empty Sandbags Are the Better Choice

Empty sandbags are generally easier for homes, farms, workshops, warehouses and commercial premises to keep as part of a flood-preparation kit.

A bundle of empty bags occupies relatively little space and can be moved easily before it is needed. This makes it possible to store supplies near vulnerable areas without permanently filling a stockroom or facilities cupboard with heavy bags.

Empty bags can also be transported to different parts of a site before filling. This may be helpful on farms, industrial premises and larger commercial properties where the area at risk can change according to the direction of the water.

Other woven sacks and related products are available within the polypropylene bags range, but businesses should select bags intended for the proposed contents and application.

Empty Bags Require a Complete Filling Plan

Buying empty bags is only the first step. Before severe weather arrives, establish:

• Where suitable filling material will come from
• Where it will be stored
• Who will fill and move the bags
• Which shovels, funnels or other tools will be used
• Where the bags need to be positioned
• How staff or residents will receive flood warnings
• What will happen if the site cannot be accessed safely

Do not assume that a local authority will provide filled bags during an emergency. Policies differ between areas, supplies may be limited and flooded or blocked roads can prevent distribution.

How Much Should a Sandbag Be Filled?

A sandbag should not be packed tightly to the top. Partially filling it leaves enough flexibility for the bag to flatten and mould against the bags around it, helping to reduce gaps in a temporary barrier.

Local flood guidance commonly recommends filling bags to around half their capacity. The precise amount will depend on the size of the bag, the filling material and how it will be used.

Overfilling can make a bag:

• Harder to close or fold
• More difficult to shape into position
• Heavier and less manageable
• More likely to leave gaps between adjacent bags
• More demanding to lift repeatedly

Use suitable sand or another filling material recommended by the relevant flood authority. Avoid soil containing sharp stones, sticks or debris that could puncture the sack.

Allow Enough People and Time

Filling sandbags is labour-intensive. One person may hold each bag open while another adds the material, after which the bag must be closed, lifted and carried to the required position.

Preparing a barrier for more than one doorway can require many bags. Businesses should not assume that a single member of staff will be able to prepare the full supply quickly or safely.

Consider:

• How many bags are likely to be required
• How long each bag takes to fill
• The distance from the filling point to the property
• Whether stairs, ramps or uneven ground are involved
• Whether trolleys or other handling aids are available
• Which employees are trained and physically able to carry out the work

Filled sandbags can be awkward to grip and should not be carried farther than necessary. Place the filling point close to the area being protected where this can be done safely.

Do Sandbags Stop Floodwater Completely?

Sandbags can help reduce or delay water entering through doorways, low openings and other vulnerable points. They can also be used to divert shallow water away from a particular area.

They should not be treated as a guaranteed watertight solution. Water may seep between or through the bags, flow around the end of a barrier or enter through drains, air bricks and other openings.

The effectiveness of a temporary barrier depends on:

• How early it is installed
• How carefully the bags are filled and positioned
• The height, speed and direction of the water
• The condition of the bags
• The ground and wall surfaces
• Whether other entry points have been addressed

Heavy-duty plastic sheeting placed between the bags and the building can sometimes improve the temporary seal. The sheeting itself must be suitable for the application and secured safely.

Properties with a known or repeated flood risk should also investigate purpose-made flood doors, flood boards, air-brick covers and non-return valves. A flood-risk professional may be able to recommend more reliable property-level measures.

What Should Businesses Keep With Empty Sandbags?

A useful flood kit may include more than the bags themselves. Depending on the property and its risk assessment, it could contain:

• A known supply of appropriate filling material
• Shovels and filling tools
• Work gloves and waterproof protective clothing
• Suitable footwear
• Torches and spare batteries
• Heavy-duty plastic sheeting
• Cleaning and hand-washing supplies
• A site plan showing vulnerable openings
• Emergency contact and utility information

Keep equipment together, clearly labelled and accessible. A kit hidden behind seasonal stock or stored in a part of the building likely to flood first may be impossible to reach when required.

Filled, Empty or a Combination of Both?

Some properties may benefit from keeping a small number of filled bags near the most vulnerable doorway, together with a larger stock of empty bags for additional protection.

This offers an immediate response while leaving enough flexibility to build up the temporary barrier if the risk increases.

A combined arrangement may suit:

• Businesses with one particularly vulnerable entrance
• Sites with sufficient sheltered storage for a small filled supply
• Properties where staff are available to fill additional bags
• Premises that experience repeated seasonal flood warnings

The filled bags must still be inspected regularly, and the empty supply must be supported by accessible filling material and equipment.

Other Uses for Empty Sandbags

Woven polypropylene sandbags are also used for suitable non-flood applications. They may provide temporary ballast for signs, covers and lightweight site equipment, or be used for landscaping and erosion-control tasks.

The bag and filling material must suit the proposed application. Do not suspend, mechanically lift or use filled bags in a way for which they have not been designed.

Sandbags used for ballast should be positioned so that they do not create a trip hazard, obstruct an access route or damage the equipment they are intended to stabilise.

Handling Sandbags After a Flood

Floodwater can contain sewage, oils, chemicals and other contaminants. Any bag that has been in contact with floodwater should therefore be treated as potentially contaminated.

When handling used bags:

• Wear waterproof gloves and suitable protective clothing
• Keep children and animals away from the bags and sand
• Wash hands thoroughly with soap and clean water afterwards
• Do not spread contaminated sand in gardens or play areas
• Keep the bags away from food preparation and storage areas
• Ask the local authority how they should be disposed of

Disposal rules vary, particularly where the bags may contain sewage, fuel, oil or chemicals. Do not automatically place contaminated sand or sacks in household or general commercial waste.

Unused bags that have remained clean and dry may be retained for future use, provided they are inspected and remain in suitable condition.

Which Option Should You Choose?

Filled sandbags provide the quickest response but require suitable storage and involve more handling before an emergency even begins. Empty bags are easier to keep and transport but rely on advance planning, filling materials and available labour.

For many homes and businesses, keeping empty bags as part of a prepared flood kit is the more practical option. Premises exposed to rapid flooding may prefer a small ready-filled supply as well.

Whichever arrangement you choose, prepare before severe weather arrives. Identify the vulnerable points, establish who will fill and move the bags, and investigate whether purpose-made flood protection would provide a more dependable long-term solution.

Martins Mill Packaging supplies woven polypropylene sandbags with ties in quantities suitable for domestic, trade and commercial use. Browse the available sandbags online or contact the team to discuss quantities and current availability.