GRP Water Treatment Products

Combining our expertise in Specialist Mouldings and Structural Products we can offer a vast range of GRP Products for the Water and Sewage Treatment Industries that outperform traditional products and deliver highly durable solutions at a lower cost.

Working with clients all around the world, we fabricate, supply, deliver and install Water Treatment products such as Launder Channels, Weir Plates, Diffusion Drums, Baffle Plates, and Scum Boards.

Having a high strength-to-weight ratio and being corrosion and conductive-resistant are just some of the main advantages of our GRP Water Treatment products. These properties can be particularly important for pipes and tanks, and for projects based on retrofitting new, or replacement equipment within existing installations or in raised locations.  

GRP can be used for rigid and self-supporting structures and is easily formed into bespoke shapes. At Relinea we can mould one-piece tanks or drums that have integral supports and other structural elements. With a sustained life expectancy, our GRP water treatment range provides the durability your industry needs, while giving you long-lasting peace of mind.

Relinea – Reliable, Resourceful

With one of the largest dedicated composite design teams in the sector combined with 15 years of experience in the manufacture of GRP water treatment products we are best placed to provide truly innovative, sustainable solutions. Our highly skilled composite fabrication teams use the latest technology and manufacturing techniques to deliver peerless results reducing the on-site adjustment time of GRP water treatment products and fabricated structures.

Give us a call today on 028 9447 0010 or email us at with your project specification to discuss your requirements and request a free quotation and proposal.  

GRP Diffusion Drums

Relinea’s Diffusion Drums are available in diameters up to 10m and a variety of depths. Deeper units would be made up of multiple tiers, bolted together. GRP Diffusion Drums can come with incorporated steel hangers and stiffening ribs. Scum doors and baffles can also be added.

GRP Launder Channels

Relinea’s GRP Launder Channels are:

  • A cost-effective and easy to install alternative to steel and concrete launder channels
  • Used to filter out the sewage liquor or water from tanks
  • Available in a variety of designs, including Z shaped, which are directly bolted to the wall, and traditional U shaped
  • Fully integrable with mounted GRP Weir Plates.
  • Designed to suit the diameter of the tank and are sized to suit the incoming/outgoing flows
  • Supplied in sections and are bolted together on-site using an approved sealing technique to generate a watertight joint

Relinea can also provide support brackets in GRP, Stainless Steel, or Galvanised Steel.

GRP Weir Plates

Relinea’s GRP Weir Plates are designed to control the flow of sewage in waste water treatment plants. Our Weir Plates are highly non-corrosive and chemical resistant, meaning that little or no maintenance is required.

  • Standard thickness: 6mm and 10mm – We can supply custom designed tank covers to suit client specification)
  • Generally 3m long with a 50mm overlap joggle joint with neoprene seals.
  • Pre-curved or straight board plates are available.
  • Weir Plates can be supplied as blank, v-notched, rectangular, flat top, castellated, and sharp crested as required.
  • Weir Plates are slotted for ease of levelling on site.
GRP Scum Boards

GRP Scum Boards are designed to retain scum build up in raw sewage liquor environments. Relinea can supply Pre-Curved or Flat Sheet Scum Board arrangements, and furthermore provide brackets manufactured in GRP, galvanised steel, or stainless steel.

  • Standard depths of 300mm – 450mm available.
  • 6-10mm thick in 3m boards with overlap joggle joint.

Durable, long-lasting, and corrosion-resistant, our GRP scum boards are the perfect cost-effective solution.

GRP Baffle Plates & Walls

Our custom Moulded and Fabricated GRP Baffle Plates and Walls are designed to direct and regulate or disrupt the flow of water and eliminate potential rapid overfill. Our Baffle Plates and Walls are a simple, robust solution that can span any type or size of tank. Lightweight components, with high strength to weight properties, are easy to handle and do not require special lifting equipment, making installation quick and easy. 

Key Benefits of GRP Water Treatment Products

Quality GRP construction with UV stable gel coat finish

Non corrosive even in very aggressive environments

Highly durable


Cost effective alternative to stainless steel

Re-Grab Ladder System

There is one area where the enhanced performance of Re-Grab GRP Handrail and Ladder Systems can be measured quickly, easily and immediately…by a simple touch. Re-Grab is warm to touch – an important factor to consider for Handrails and Ladders that are being used in outdoor contexts.

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