Nexus Barrier System: A UK Guide to Water Filled Barriers, Panels and Couplers
By the Securasite team. Updated 22 October 2026.
A water filled barrier is a hollow plastic barrier that you fill with water or sand on site. It weighs 28kg empty, so it is easy to move, and 408kg once filled, so it stays where you put it without ground fixing. This guide covers the Nexus Water Filled Barrier and the four parts that complete a run: mesh panels, hoarding panels, B1 buttress flags and SMLC couplers. It shows what each part does, how many to order and where the system sits against other options.
Quick answers
What is it? A water filled barrier with a 2m working length and 90 degree jigsaw links. Bolt-on mesh or hoarding panels take it from 0.8m to 2.15m high.
What makes a complete run? Barriers, one panel per barrier, one SMLC coupler per panel and your own ballast. B1 buttress flags are an optional extra.
Which tools? An 8mm Allen key for the panel screws and a 21mm spanner for the couplers.
What order? Link and fill the barriers first. Only fit panels after the ballast is added.
Which colours? Red and white in any quantity. Bespoke RAL has a minimum of 96 and takes 2 to 4 working weeks.

Nexus Water Filled Barrier 2m
L2313 x H845 x D400mm. 28kg empty, 408kg filled.
From £185.00 ex VAT
View product
Nexus B1 Buttress Flag
L305 x H1345 x D76mm. 3.5kg. Fixed with 4 SMLC couplers.
£95.00 ex VAT
View product
SMLC Coupler
Two-arm clamp with threaded bolt. Tightened with a 21mm spanner.
£4.50 ex VAT
View productPlanning a project? Use the run planner below, then request a quote or call us on 0330 056 4420.
What is the Nexus system?
Nexus is a modular perimeter system built around one barrier. The barrier has a 2m working length and 90 degree jigsaw links, so the same ballasted unit forms a straight run, a corner, a fork or a T, X or Y junction. It also links to other barrier types, which makes it useful where you are joining new barriers to ones already on site.
Water filled barriers suit places where ground fixing is not an option. You move the barrier empty, fill it where it stands and drain it when the job ends. The Nexus holds up to 380L of water or sand through a 95mm fill hole and drains through a 25mm drain hole. Bolt-on panels then take the barrier from 0.8m to 2.15m high, with mesh where you want to see through the perimeter and solid hoarding where you want to screen it.


Nexus barrier at a glance
| Specification | Nexus Water Filled Barrier 2m |
|---|---|
| Working length | 2000mm |
| External size (L x H x D) | 2313 x 845 x 400mm |
| Weight, empty and filled | 28kg empty, 408kg filled |
| Fill capacity | 380L (water or sand) |
| Fill and drain holes | 95mm fill, 25mm drain |
| Material | UV MDPE |
| Maximum link angle | 90 degrees |
| Fork channels | 2 x 204 x 89mm |
| Colours | Red, white or Bespoke RAL |
| Reflective option | Option 1 adds 2 x reflective strips |
Looking at the whole range? See our Chapter 8 and water filled barriers.
The five parts of a Nexus run
A run is built from five products. Only the barrier is essential, because the panels, flags and couplers are what turn it into a 2.15m perimeter. Quantities follow a simple rule for each part:
| Part | What it does | Size and weight | How many |
|---|---|---|---|
| Nexus Water Filled Barrier 2m | The ballasted base. Links to the next barrier through the jigsaw links. | L2313 x H845 x D400mm. 28kg empty, 408kg filled. | One per 2m of run, rounded up |
| Nexus Mesh Panel | Bolt-on white steel mesh panel. See-through perimeter. | L1949 x H1345 x D183mm. 13.5kg. | One per barrier |
| Nexus Hoarding Panel | Bolt-on solid white steel panel. Screened perimeter. | Same size and fixings as the mesh panel. 20kg. | One per barrier, in place of the mesh panel |
| Nexus B1 Buttress Flag | Fitted at forks and B1 buttress junctions where panels meet. | L305 x H1345 x D76mm. 3.5kg. | Optional. Ask us how many your layout needs |
| SMLC Coupler | Two-arm clamp coupler. Joins panels, fixes flags and fits B2 buttress barriers. | Tightened with a 21mm spanner. | 1 per panel, 4 per B1 flag, 2 per B2 barrier |
Mesh and hoarding panels are the same size and use the same fixings, so you can mix them along a run. A panel fitted to a barrier gives a total height of 2145mm.
Height at a glance
Front outline drawn to scale. Barrier 2313mm long, panel 1949mm long. The panel overlaps the top of the barrier slightly, giving 2145mm in total.
Where the B1 buttress flag fits
The flag is fitted at forks and B1 buttress junctions, where mesh or hoarding panels meet. It stands the same 1345mm high as the panels and is fixed with 4 SMLC couplers and a 21mm spanner. It is an optional extra, so check your layout with us if you are unsure whether a junction needs one.


How a Nexus run goes together
The order matters, mainly because the panels go on last. This is the sequence from the Nexus fitting instructions, in plain terms. Follow the instructions supplied with the product and your own site method statement for the full detail.
Position and link the barriers
Offer each barrier to the next and link them through the jigsaw links. Corners go up to 90 degrees, and T, X and Y junctions use the same links.
Fill with ballast
Fill each barrier through the 95mm fill hole with up to 380L of water, or with sand. A filled barrier weighs 408kg.
Fit the panel
Fit panels only after the ballast is added. Locate the 4 x M12 fasteners and washers and tighten them with an 8mm Allen key. The panel is reversible.
Join with an SMLC coupler
Position the SMLC coupler on the posts of the neighbouring panels and tighten it with a 21mm spanner. Use one coupler per panel.
Add flags at junctions
Where panels meet at a fork or B1 buttress junction, fit a B1 buttress flag using 4 SMLC couplers.
Buttress where needed
A B2 configuration can be linked to a straight perimeter to provide added wind resistance. Each B2 barrier uses 2 couplers. For exposed sites, speak to our team.


Nexus run planner
Enter the length of your perimeter and choose your panels. The planner works out the barriers, panels, couplers and flags to order, with list prices ex VAT and links to each product.
Measured along the perimeter. Each barrier covers a 2m working length.
Optional. Each flag adds 4 couplers.
Optional. Counted as extra barriers with 2 couplers each.
Your parts list will appear here. If it does not, enable JavaScript or call us on 0330 056 4420.
Corners, junctions and sloping ground can change the count by a barrier or two. If your site layout is complicated, send us a plan and we will check it before you order.
Choosing the barrier: colour and options
The barrier comes in six variations: three colours, each with a Standard or an Option 1 version. Option 1 adds 2 x reflective strips. Red is the only colour without a minimum order, so it is the practical choice for small and mid-size runs.
| Colour | Version | Minimum order | Price each ex VAT | Choose it when |
|---|---|---|---|---|
| Red | Standard | None | £185.00 | You need a run of any size, from a few barriers up |
| Red | Option 1 (2 x reflective strips) | None | £210.00 | You want reflective strips on a red barrier |
| White | Standard | 96 | £185.00 | A white barrier is specified and the quantity justifies it |
| White | Option 1 (2 x reflective strips) | 96 | £210.00 | As above, with reflective strips |
| Bespoke RAL | Standard | 96 | £210.00 | A client or brand colour is specified |
| Bespoke RAL | Option 1 (2 x reflective strips) | 96 | £235.00 | As above, with reflective strips |


For a custom shade, tell us the RAL code and the quantity and we will confirm availability before you order. Call 0330 056 4420 or request a quote.
Mesh panel or hoarding panel?
Both panels bolt to the same barrier in the same way, so the choice comes down to what the perimeter has to do. Mesh lets you see through the line. Hoarding is solid, so it screens the site from view.
On smaller screens, swipe the table sideways to compare both panels.
| Factor | Nexus Mesh Panel | Nexus Hoarding Panel |
|---|---|---|
| Panel type | Mesh | Solid |
| Panel size (L x H x D) | 1949 x 1345 x 183mm | 1949 x 1345 x 183mm |
| Total height on barrier | 2145mm | 2145mm |
| Weight | 13.5kg | 20kg |
| Material and finish | Powder-coated steel, white | Powder-coated steel, white |
| Fixings | 4 x M12 x25 screws and washers | 4 x M12 x25 screws and washers |
| Couplers | 1 x SMLC coupler per panel | 1 x SMLC coupler per panel |
| Price ex VAT | £49.00 | £125.00 |
| Choose it when | You want to see through the perimeter | You want to screen the site from view |

Check your site's wind and exposure requirements before choosing a solid panel for a long or exposed run. Our team can advise, and a B2 configuration may help on straight perimeters.
View the Nexus Mesh Panel or the Nexus Hoarding Panel. If you only need a steel hoarding that is fixed to the ground rather than ballasted, see our hoarding range.
Linking Nexus to other barriers
The Nexus links to other barriers through its stack lugs and its jigsaw link, using the SMLC coupler. This is useful when a site already has other water filled barriers or pedestrian barriers and you want one continuous perimeter. The table shows what the Nexus data sheet lists as compatible.
| Product | Connects to the Nexus | Notes |
|---|---|---|
| Novus Barrier (male link end, with or without mesh) | Nexus female link | Mesh end and coupler are used where a Novus mesh panel is fitted. |
| RB22 Crash Barrier (female end) | Nexus male link | The RB22 female end nests with the Nexus male link. |
| Evo Stackable with Mini Mesh Panel for Evo | Nexus link at the barrier pin end. Nexus lugs and link at the flat end. | Link end orientation affects which lugs can be used. |
| EvoGator with mini mesh | Nexus link at the barrier pin end. Nexus lugs and link at the flat end. | As for Evo. |
| ROTA Slot with 3.5m mesh | Nexus lugs and link, at the mesh ends | Listed for both connections. |
| Firmus Pro and Firmus Premium | Nexus lugs and link | Pin connection. |
| 2.3m pedestrian barrier and walkthrough, 3.5m mesh with feet | Nexus lugs and link | Connection is at the end rails. |

Quantities and positions depend on the combination you are building, so tell us what is already on site before you order. We will confirm the couplers and any adapters you need.
Six ordering mistakes to avoid
- Fitting panels before the barrier is filled. The instructions say to install panels only after the ballast is added. Fill first, then fit.
- Not counting the couplers. You need 1 SMLC coupler per panel, 4 per B1 buttress flag and 2 per B2 barrier. Ask us what is packed with your panels so you do not buy duplicates or run short.
- Forgetting the tools. Panels need an 8mm Allen key for the M12 screws, and couplers and flag nuts need a 21mm spanner.
- Assuming ballast is supplied. The barrier is sold empty. Plan for up to 380L of water or sand per barrier.
- Choosing white or Bespoke RAL for a small run. Both are supplied in minimum quantities of 96. Choose red for smaller orders.
- Skipping the layout check. Corners, forks and exposed edges can change quantities and may call for flags or a B2 configuration. Send us the plan and we will check it.
When to choose something else
- Other water filled barriers: for a different size or a stackable format, look at the Evo Stackable barrier or the EvoGator.
- Crash-rated and road safety barriers: these are a separate product group. Check the rating you need in our Chapter 8 and water filled barrier range.
- Ground-fixed or foot-supported fencing: where feet and couplers are enough, see our temporary fencing panel guide and temporary fencing range.
- Steel hoarding: where you can fix to the ground, the Galvanised Steel Hoarding Panels give a solid screen without ballast.
- Pedestrian-only separation: read our pedestrian barrier comparison guide or the expanding concertina barrier guide.
Not sure which route suits your site? Call us on 0330 056 4420 and we will point you to the right product.
Frequently asked questions
Quick answers to the questions buyers ask most. Select a question to see the answer.
What is a water filled barrier and how does the Nexus work?
+
A water filled barrier is a hollow plastic barrier that you fill on site with water or sand, so it holds its position without ground fixing. The Nexus Water Filled Barrier has a 2m working length and 90 degree jigsaw links for corners and T, X and Y junctions. It weighs 28kg empty and 408kg filled with 380L of water.
How many barriers do I need for my run?
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Each barrier has a 2m working length, so divide the run length by 2 and round up. A 20m straight run needs 10 barriers. Corners and junctions can change the count, so send us your layout and we will check the quantities. The run planner above gives a quick estimate.
How many SMLC couplers do I need?
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You need 1 SMLC coupler per mesh or hoarding panel, 4 per B1 buttress flag and 2 per B2 buttress barrier. Our team can confirm what is packed with your panels before you add extras.
Can I fit the panels before filling the barriers?
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No. Fill the barriers with ballast first, then fit the panels. Each panel is fixed with 4 M12 fasteners and washers, tightened with an 8mm Allen key, and joined with an SMLC coupler tightened with a 21mm spanner.
What can I fill a Nexus barrier with?
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Up to 380L of water, or sand. The fill hole is 95mm and the drain hole is 25mm. Ballast is not supplied with the barrier.
Which colours are available and is there a minimum order?
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The barrier comes in red, white or Bespoke RAL. Red and white are available in any quantity. Bespoke RAL is made to order, with a minimum of 96 barriers and a lead time of 2 to 4 working weeks. Option 1 adds 2 x reflective strips. For a custom shade, call us on 0330 056 4420 or request a quote.
Can the Nexus link to other barriers?
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Yes. The Nexus data sheet lists Novus, RB22, Evo1M and EvoGator with mini mesh, ROTA Slot with 3.5m mesh, Firmus Pro, Firmus Premium and 2.3m pedestrian barriers as compatible when used with a coupler. Positions and quantities depend on the combination, so contact our team before ordering for a mixed run.
Do I need B1 buttress flags?
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Flags are an optional extra. They are fitted at forks and B1 buttress junctions where mesh or hoarding panels meet, using 4 SMLC couplers each and a 21mm spanner. Tell us your layout and we will confirm whether your junctions need them.
Get your Nexus run
Buy direct from us. Order the parts online, or send us your layout and our team will confirm the barriers, panels, couplers and flags before you order.
Tell us:
- The length of the run and any corners or junctions
- Mesh or hoarding panels, or a mix
- Barrier colour, and whether you need reflective strips
- Whether you are linking to barriers already on site
Or email sales@securasite.co.uk.
More guides
- Temporary Fencing Panels UK: Round Top, Low-Level and Extra Tall Guide
- Choosing the Right Securasite Pedestrian Barrier
- Site Storage Boxes: A UK Buyer's Guide to the Securasite Lockbox
Looking for something else? Browse our full range.



















































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