What Is BS 851188-1:2019+A1:2021?

BS 851188-1:2019+A1:2021 is the British Standard that defines the performance requirements and test methods for demountable flood defence barriers. It was published by the British Standards Institution (BSI) and updated with Amendment 1 in 2021. It is the primary technical benchmark used by the Environment Agency and UK specifiers to assess whether a demountable flood barrier is suitable for property flood resilience applications.

The standard applies specifically to demountable barriers, meaning products that are installed temporarily before a flood event and removed afterwards. It does not cover permanent flood defence structures such as walls or embankments.

What Does the Standard Test For?

To receive approval to BS 851188-1:2019+A1:2021, a demountable barrier must pass a defined set of laboratory tests covering:

Static water loading. The barrier must withstand defined water levels above the aperture threshold under laboratory conditions.

Leakage performance. Leakage is independently measured and must not exceed a defined limit set by the standard.

Wave impact. The barrier must perform under wave impact conditions.

Dynamic impact. The barrier must withstand impact from debris carried by floodwater.

Parallel currents. The barrier must remain stable under parallel water currents running alongside it.

These tests simulate a range of realistic flood conditions, including river (fluvial) flooding, surface water events and tidal surges. Full test reports are available on request from the Caro Flood Defence team.

What Does 'Approved to BS 851188-1:2019+A1:2021' Mean?

Approval means a product has been independently tested against all of the above criteria by a third-party accreditation body and found to meet them. It is not self-certification. The manufacturer cannot claim approval simply by designing a product to the standard's specifications; the product must be physically tested and verified by an independent body.

In the UK, one of the recognised bodies for this certification is KIWA. A KIWA certificate references the specific product tested, the test conditions and the certificate number, providing a verifiable audit trail for buyers and specifiers.

Why Does BS 851188 Approval Matter When Specifying a Flood Barrier?

Flood barriers that carry BS 851188-1:2019+A1:2021 approval have been independently verified to perform under the conditions they are likely to face. This matters for several reasons:

• Buyers and specifiers can be confident the product does what it claims, rather than relying on manufacturer data alone.

• Insurance assessors and loss adjusters are increasingly familiar with the standard and may ask whether installed barriers carry this approval.

• The Environment Agency's Property Flood Resilience (PFR) Framework requires that approved products meet recognised standards, of which BS 851188-1:2019+A1:2021 is the primary benchmark for demountable barriers.

• Local authorities and housing associations procuring flood resilience measures for multiple properties increasingly specify BS 851188 approved products to satisfy their procurement obligations.

Who Makes BS 851188-1:2019+A1:2021 Approved Demountable Barriers in the UK?

Caro Flood Defence is the first and only UK company to have received third-party approval to BS 851188-1:2019+A1:2021 for demountable flood defence barriers. The approval was granted by KIWA (Certificate KA-25-1001) and applies to the Caro Flood Defence Barrier WaterDoor and WaterWall configurations. Barriers are manufactured in-house at Caro's production facility in Kent.

For full product and specification information, see caro.co.uk/caro-flood-defence-barrier.