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Potable vs Non-Potable Water Tanks: Explained

Updated: Jan 11

When choosing a water storage tank, one consideration to make is whether you will need a potable water tank or a non-potable tank. Whether you’re purchasing a tank for use in your home or for commercial use, it is important to ensure you know which type you will need as purchasing a tank that isn’t fit for your requirements can be a rather frustrating mistake!


Getting straight to the point, a potable water tank, otherwise referred to as a drinking water tank, is a tank which is approved to store water that is fit for human consumption. This not only refers to drinking water but also water which may be used for food preparation, catering, washing-up, bathing or showering.


There are many situations where a potable tank will be necessary, which we will outline in this article below.

Similarly, there are many other situations where a non-potable tank is sufficient, such as in the case of rainwater harvesting where a standard rainwater harvesting tank or water butt can be used.


What is Potable Water?


Potable water is water that has been treated and tested as safe for human consumption, otherwise referred to as drinking water. This includes tap water, bottled water, filtered water, and any other water considered safe for drinking and food preparation.


Not only does drinking water need to be appropriately treated and tested, but it also needs to be appropriately stored, and this is why regulations state that water intended for human consumption must be stored in a potable water tank.


The Difference Between Potable VS Non-Potable Water Tanks


There are several key differences between potable and non-potable water tanks, including the type of material the different tanks are made of and the manufacturing processes.


Potable Tanks


Potable tanks for storing drinking water are tanks which have been manufactured from Water Regulation Approval Scheme(WRAS)-approved polymers and are also sometimes referred to as WRAS-approved tanks.


WRAS is an independent UK certification body that helps businesses and consumers to use water supply and storage products that comply with the Water Supply (Water Fittings) Regulations 1999 and Scottish Bylaws, to ensure that water intended for human consumption is fit and safe for purpose. This includes ensuring the plastic does not spoil the water being held inside the tank (i.e. by encouraging bacteria growth or emitting particles or gases), rendering it unsafe for human consumption. 


Popular Uses for Potable Tanks


Potable water tanks have a wide range of uses and specifications to meet depending on the application. Typical uses and settings of potable water tanks include:

■       Bulk water storage

■       Back-up emergency drinking water supply

■       Food industry

■       Brewing and winemaking sectors

■       Temporary water supply for events and festivals

■       Domestic water solutions

■       Civil engineering applications where mains water is unavailable


Non-Potable Tanks


Non-potable tanks are water storage tanks which are not WRAS-approved for drinking water. Non-potable tanks can be used for domestic, industrial and commercial applications.


They are designed for the storage of non-drinking water which can be used for everyday use across many different industries and applications that do not involve human consumption. They are often used for harvesting and storing rainwater which similarly, has many uses.


The most common uses of water stored in non-potable tanks include toilet flushing, horticultural and orchard/market garden applications, watering lawns and flower beds, agricultural irrigation or are where mains water is not available such as on construction or development sites and at outdoor events.


Underground Potable Water Tanks


In certain instances, above-ground potable water storage may not be an option because of space restrictions or insulation purposes and a below-ground, or underground potable tank installation may be required.


Can a Potable Water Tank Be Connected to the Mains Water Supply?


Potable drinking water tanks can indeed be connected to a mains supply, however, in most instances, an approved Fluid Category 5 AB Air Gap Break tank will be required by most water authorities to prevent contamination into the incoming mains supply.


Additionally, the tank will usually need to be insulated to prevent thermal gain and loss which can occur in certain situations, such as in the case of outside potable water storage.


Underground potable tanks can also come with a category 5 turret but are bespoke-made dependent on the application as to the height of the turret.


Note: The WRAS Fluid Categories identifies the level of water contamination risk, with Category 1 being wholesome and safe drinking water and Category 5 referring to water that poses a serious risk due to the presence of pathogenic organisms or other toxic or dangerous substances. 

Figure 1: Rainwater Harvesting Installation - Mains Back-up into left-hand Cat 5 Tank

Potable Water Tank Colour Options


Both standard and category 5 potable water tanks come in two colour options; black and blue. Blue tanks command a premium price but can prevent confusion by human error. For instance, at an event where tanks are used temporarily to supply drinking but there may also be black waste holding tanks on site, a blue potable water tank can help to distinguish between drinking water and non-drinking water.



Do I Need A Potable Tank & Which One Do I Need?


The choice of tank can at first appear confusing but there are two key questions:


#1 Firstly, does the product being stored need to be of drinking water quality?


#2 Secondly, is the tank going to be connected to a mains water supply?


If it is being used for drinking water but not connected to a mains supply a standard potable tank is suitable.


If it is being connected to a mains supply then a Cat 5 break tank is required. However, you may have a combination of the two in one installation. Essentially if the correct tank is chosen for the correct use, the hard work is done for you and the tanks meet specific regulations to be used for specific installations. However, care must be taken to ensure the entirety of an installation and all other products and fittings used also meet the regulations to ensure compliance.


Looking To Purchase Your Tank?


If you’re looking to purchase a potable drinking water tank then take a look at our extensive range of tanks, including above-ground potable water tanks and underground potable water tanks. If you are still unsure or want to double-check which type of tank you need, we’re always happy to help and advise, just get in touch and we’ll help you choose the correct tank. Additionally, if you can’t find the tank you require on our site, we can also help you to source the one you need.



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