Select Page


We at Dewey Waters will endeavour to answer all of your questions regarding legislative issues or our product range and services.

Tank Tips & FAQS

Prolonging a Tank Installation

To ensure you get longevity of life from your tank installation, when conducting your annual clean in accordance with ACOP L8 & HSG274. Always check for any loose bolts before refilling.

Useful Links:

Warranty Statement


All Dewey Waters Limited products are fully warranted in respect of workmanship and materials for twelve months from the date of installation for sectional tanks, and receipt of goods for all other products. Outside this period Dewey Waters Limited will investigate and rectify problems upon request but reserve the right to make a charge for these services to be determined at the time. Extended warranties are available by negotiation.

It would be expected under normal conditions of service that Dewey Waters Limited GRP potable water storage tanks and static associated peripherals would have a maintenance free service life in excess of twenty years. Moving parts, such as valves, would be expected to require servicing / replacement as recommended by the manufacturer thereof. Operation and maintenance statements for sectional and one piece GRP potable water storage tanks are available from Dewey Waters Limited.

What's a type AB air gap?

This is a non-mechanical backflow prevention arrangement. The water is discharged through an air gap which has at all times an unrestricted spillover to the atmosphere. This is required to protect the mains water supply from back siphonage of a category 5 fluid application such as Process, Medical or Grey water recycling systems.

What does TIF, IFB and EFB stand for?

They are all acronyms relating to the flanges of our sectional tanks.

  • TIF – Totally Internally Flanged (all internal bolting)
  • IFB – Internally Flanged Base (externally flanged sides)
  • EFB – Externally Flanged Base (externally flanged sides)
What space do I need around my tank?

This will depend upon the type and height of tank you require, an approximate guide as follows:

  • IFB under 2m high – 500mm on all 4 sides and 750mm* above
  • IFB 2m > 3m high – 800mm on all 4 sides and 750mm* above
  • IFB 3.5m & 4m high - 1000mm on all 4 sides and 750mm* above
  • EFB under 2m high- 500mm on all 4 sides, 600mm underneath and 750mm* above
  • EFB over 2m > 3m high- 800mm on all 4 sides, 600mm underneath and 750mm* above
  • EFB 3.5m & 4m high - 1000mm on all 4 sides, 600mm underneath and 750mm* above
  • TIF – 50mm on 3 sides, 500mm on 1 side and 750mm* above

*1200mm when fitted with a Guardrail

Please note the clearance above can be reduced to a minimum of 500mm with the inclusion of a ‘lift off kit’. The clearance around tanks over 2m can be reduced depending on site conditions. Please speak to our technical sales team on +44 (0) 1934 421477 for further information.

Why would I need a totally internally flanged tank?

Standard access requirements request a minimum clearance of 500mm around all four sides of the tank for assembly and maintenance purposes. With the TIF design these access requirements are reduced to 50mm on three sides and 500mm on one side. The tank may be positioned up against a wall or column, allowing space for other equipment within the plant room.

What is your maximum height tank?

This is currently 4m for Hot Press Sectional Tanks, 3m for our Totally Internally Flanged tanks and 2.2m One Piece Specials, however, we are always striving to develop our products and manufacturing methods.

What thickness of insulation do you offer?

38mm as standard (0.57w/m2/⁰C), 50mm (0.40w/m2/⁰C) is also available

Totally Internally Flanged Sectional Tank

25mm as standard (0.85w/m2/⁰C), 50mm (0.40w/m2/⁰C) is also available

25mm as standard, 50mm (0.40w/m2/⁰C) and 75mm (0.27w/m2/⁰C) are also available


Visit our Knowledge Hub for all water tank related information, supporting documentation, technical
data, downloads and more..

GRP Tank Manufacturer & Supplier with over 60 Year Experience

Dewey Waters is one of the UK’s market leaders in the manufacture and supply of all cold water storage tanks. We specialise in sectional tanks (1,000 to 1,500,000 litres) and one piece tanks (from 30 to 9000 litres) we offer standard size tanks or custom built tanks to suit individual project requirements. We also provide a range of other GRP manufactured products including housings and biofilters, as well as kiosks and cabinets. We provide full project management for jobs of all sizes and also offer our clients training on the installation of water tanks. GRP Tanks are ideal in the storage of cold water offering a durable solution which can withstand heavy impact, weather conditions and heavy loads.