Nominal Capacity vs Actual Capacity 

NOMINAL CAPACITY 

ACTUAL CAPACITY 

ACTUAL USEABLE CAPACITY 

Nominal Capacity

This is the volume of the tank when filled to the brim. Calculated by multiplying the length x width x height e.g. 3m x 2m x 2m = a nominal capacity 12,000 litres.

Actual Capacity

This is the top water level volume when you have taken in to account the amount of water lost when fitting an overflow and warning pipe. If the TWL (top water level) loss was 200mm then you deduct this figure from the overall height. For example: using a 3m x 2m x 2m tank you would calculate the actual capacity of the tank as follows: 3m x 2m x 1.8m = an actual capacity 10,800 litres.

Actual Useable Capacity

This is the available amount of water you can physically use in the tank before you start taking air into the system. It is calculated between two datum points; the top water level volume (see actual capacity) and a dimension at the bottom of the tank, which is either the top of the outlet or the low-level switch (pump protection). This is often referred to as dead water as you technically can’t use it.

Example: How to Calculate Actual Useable Water Tank Capacity

So if this area of water was 300mm you would add this to the TWL figure and then subtract this from the overall height. So using a 3m x 2m x 2m tank you would calculate as follows:

200mm (TWL) + 300mm (Dead water) = 500mm

2000mm (2m) – 500mm = 1500mm

3m x 2m x 1.5m = an actual useable capacity of 9,000 litres

 

Effective Capacity 

This is the available amount of water you can physically use in the tank before you start taking air into the system and is calculated in the same manner as an ‘Actual useable capacity’. However, the term ‘Effective Capacity’ is used by sprinkler companies for sprinkler and wet riser tanks.

WORK WITH US ON YOUR NEXT PROJECT

We offer high quality manufactured GRP products. All our products are tested and certified to the highest standards.

Cold Water Storage Tank Range

Dewey Waters has gained an established reputation for manufacturing large and small-scale cold water storage tanks for their customers at home in the United Kingdom and throughout the world.

HOT PRESS SECTIONAL  

SUITABLE FOR LARGER PROJECTS UP TO 4 METERS HIGH

Dewey Waters specialise in hot press compression moulding at our manufacturing locations. This is a cost effective modular solution which is WRAS approved and suitable for the storage of wholesome & potable water. We can cater for all water tank specifications for Export projects or domestically here in the UK.

TIF SECTIONAL TANKS

IDEAL FOR MAXIMIZING CAPACITY IN RESTRICTED SPACES

Our range of totally internally flanged (TIF) sectional water storage tanks suit all applications and are ideal where space is restricted. Due to its internally flanged design, this tank can be installed against walls and into corners thereby maximizing water storage capacity. 

ONE PIECE TANKS

 STOCK OPTIONS AVAILABLE FOR COST EFFECTIVE WATER STORAGE 

Dewey Waters manufacture and supply one piece water tanks. Our new range offers taller and narrower tanks for common plantroom space issues. Our tanks are approved and certified in accordance with current regulations.WRAS (Water Regulations Advisory Scheme)

FIRE SPRINKLER TANKS

LPCB CERTIFIED TANKS FOR COMMERCIAL & INDUSTRIAL APPLICATIONS

Dewey Waters is a certified supplier of LPCB sprinkler tanks which are trusted by businesses, municipalities and their insurers who rely on the availability of an emergency water supply to sprinkler systems in the event of a fire.

DEWEY WATERS FEATURES

Specialising in the manufacture of both one piece and sectional cold water storage tanks, our experience ensures that we are able to accommodate virtually all client requirements.

On time Delivery

Placing and receiving your order is a straightforward, hassle-free process.

Technical Advice

We provide high levels of technical knowledge, product choice and customer service.

Fully Certified

Dewey Waters is an accredited & certified GRP water tank manufacturer.

Experts Installation

60 years’ industry experience in both Water Storage and GRP industries.

On Time Delivery

Placing and receiving your order is a straightforward, hassle-free process.

Technical Advice

We provide high levels of technical knowledge, product choice and customer service.

Fully Certified

Dewey Waters is an accredited & certified GRP water tank manufacturer.

Experts Installation

60 years’ industry experience in both Water Storage and GRP industries.

CONTACT US

Do you need help, or have a question?

Please use the form below and one of our experts will be in touch shortly.

Get a FREE Quote!

Please use this form below and one of our experts we'll be in touch shortly.