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NP overflow

Overflow and Warning Pipes



Understanding the importance of correctly installed warning and overflow pipes will help in limiting water damage in buildings.

Warning and overflow pipes that are not plumbed correctly can lead to thousands of pounds worth of damage. Failure to plumb the warning pipe to a monitored area may lead to faults going undetected for a long period of time. The role of the warning pipe is to alert personnel of rising water levels in the water storage tank, indicating a fault or malfunction with the inlet or other connections. If undetected, water levels will continue to rise and exit the tank through the water tank overflow. It is vital that overflow piping is plumbed correctly to a gully or bunded area to accommodate overflow water and avoid flooding, water damage, and possible costly repairs.


Example of Standard Overflow Pipe Plumbing

Overflow piping

WRAS Guidelines for Warning Pipes and Overflow

‘Warning pipe’ means an overflow pipe with its inlet located in the cistern at such a height that it will start to flow before the main overflow operates and with its outlet located in a position where the discharge of water can be readily seen.

Source WRAS

Wherever possible warning pipes should discharge outside a building, however where this is not practicable owing to the design of the building, they may be discharged internally provided the discharge is conspicuous. View the WRAS regulation guide for examples of acceptable arrangements for the discharge of the warning/overflow pipe.

Source WRAS Regulations Guide

For more information please review our recommended WRAS guidelines below. We offer water storage solutions for all applications contact our sales team or view our products page for more information. For more information on our range of cold water storage tanks available visit our products page, alternatively please contact our expert sales team for correct tank selections for your job.

Benefits of working with Nicholson Plastics

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Expert Leading

Manufacturing GRP cold water storage solutions for domestic, industrial, agricultural & commercial industry sectors since 1968. 

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CPD Training

We have created a CPD training course to develop and improve industry professionals with the correct skills in specifying water storage solutions.

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ISO Certified

Our cold water storage tanks including WRAS approved, are manufactured to the highest quality and ISO standards.

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Team Tank Care+

We provide a dedicated customer support team to help with technical queries including drawing returns, delivery, installation & site support.

Cold Water Storage Tank Solutions

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Sectional Tank

✓ Highest quality standard

✓ Bespoke design

✓ UV stabilised materials

✓ WRAS approved

Glen Mhor Case Study

Combined Sectional Tank Enclosure

✓ Very Compact

✓ Professional enclosure

✓ GRP material

✓ Corrosion resistant

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One Piece Tank

✓ Bespoke design

✓ Virtually ZERO maintenance

✓ Can be supplied in any BS5252 or RAL colour

✓ WRAS approved

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Break Tanks

✓ Available from a standard range

✓ Pre-insulated tanks

✓ Standard capacities are available

✓ WRAS approved

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Two-part Tanks

✓ Manufactured to order

✓ Available with insulation in varying thicknesses

✓ Fully self-draining

✓ WRAS approved

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Category 5 Tanks

✓ Uses for urinals, laboratories, drain cleaning plants, industrial cisterns and bins, etc.

✓ UV stabilised materials

✓ WRAS approved Type AB - Air gap

Why work with us for your Water Storage Needs?

Over 50 years’ industry experience

Projects completed in the last 24 months

Tricel Lanark is a UK GRP Cold Water Storage Tank Manufacturer with a proven track record in the supply of water tanks to all industry sectors throughout the UK. We have an expert team on hand with over 50 Years' industry experience. Our team works hard to provide exceptional industry lead times from quotes, site visits, order processing, and delivery. We are a British Standard approved company with full certification through BSI/ISO9001 including WRAS approved certified water tanks suitable for potable drinking water.

  • Over 50 years of technical knowledge.
  • Quality assurance at a local level.
  • UK customer support teams, backup, replacement service & advice.
  • Supporting local and sustaining UK manufacturing.
  • Regional sales representatives for site visits, emergency water requirements, and project advice.


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Our Accreditations

At Nicholson’s, we pride ourselves in manufacturing and installing GRP water tanks of the highest quality throughout the UK. Click to see Our Certifications.


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bsi member cert
Certified ISO company
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chas accredited contractor
safe contractor approved