Potable and Non-Potable water – why have different tanks?
Firstly, what do the terms mean? Potable water, in short, is drinking water. Non-potable water generally would be rainwater or other untreated water – used for cleaning, irrigation or possibly livestock drinking water, but not safe for human consumption or personal hygiene.
Potable water tanks are designed to be used indoors or outdoors, and therefore to prevent deterioration of the water quality, they need to be opaque to cut out the sun’s UV rays, which can cause algae and bacterial growth. So potable water tanks are usually black, but we also supply them in opaque blue or dark green. Black tanks are the default and the other colours may incur an additional cost, but many people do prefer water tanks to be blue or green.
Non-potable water tanks, on the other hand, can be ‘natural’ which is slightly translucent white. This helps with checking fluid levels as you can see from the outside of the tank how much is left, without even a gauge.
Potable plastic water tanks
These have to be WRAS (Water Regulations Advisory Scheme) approved materials to be sold as suitable for potable water. Not only the tank, but all its fittings need to be WRAS approved. Potable water tanks come with a Byelaw kit – Byelaw 30 in England and Wales; Byelaw 60 for Scotland – the difference being in the size of fittings. This consists of the required tank connector outlet and vent/breather with the relevant grommets. It is designed to keep the tank free from contaminants and is a legal requirement for potable water tanks. 
Harlequin’s range of potable plastic water tanks supplied by Tanks-UK are fully approved by WRAS; and the Enduramaxx potable plastic water tanks are also manufactured in the UK from WRAS-approved polymer. Tanks-UK also supply a number of other WRAS-approved plastic water tanks, including our new Polytank range of smaller tanks suitable as domestic or commercial loft tanks.
The other regulatory requirement (Regulation 3) for potable water tanks is that the installer is competent and approved, as they will be connecting to the public water system in most instances. Tanks-UK only use approved installers.
Non-potable plastic water tanks
This is a more diverse range of tanks, including:
- Rainwater harvesting tanks and systems
- Dosing tanks
- Water Butts – take a look at our new range of stylish water butts HERE
- Fire tanks – water storage for hose use or sprinkler system supply
- Irrigation system water storage
Non-potable water tanks used outside are commonly also suppled in black, but, as previously mentioned, they can be supplied in natural or other colours.
Another type of plastic water tank supplied by Tanks-UK is the range of wheel arch tanks manufactured by Wydale. These are ideal for vans and camper conversions, providing a compact way to store washing water, or for window cleaners, pressure washer supply, etc.
Water Categories
The Water Supply (Water Fittings) Regulations categorise water in 5 categories:
- Wholesome clean (drinking) water – i.e. potable water
- Water ‘whose aesthetic quality is impaired’, due to temperature or additives – e.g. water from a hot water system
- Water which may present a slight health hazard due to additives of low toxicity
- Water which presents a significant health hazard due to concentrations of toxic substances or organisms
- Water which presents a serious health hazard due to pathogens, radioactive or very toxic substances – this includes effluent but also potentially legionella contaminated water.
What is CAT5 protection?
CAT5 is short for Category 5 fluid (serious health risk). In some circumstances you might need a CAT 5 Air break fitting which prevents water from backflowing into the public water system. It works, as the name implies, by providing an actual airlock break between the inlet and the outlet. This may be a requirement for mains-fed fire sprinkler storage tanks, for instance, or any other storage tanks where there is a possibility of legionella bacteria build up due to temperature or the length of time the water has to be stored – e.g. washdown systems in some agricultural or industrial applications. We can advise on what you need and supply the CAT5 AB fittings where required.
Just give us a call on 01953 665940 or email info@tanks-uk.com with your requirements and we’ll send you a quote.