Specifying potable water tanks for a commercial or industrial facility is one of those decisions that looks straightforward until it isn’t. Get the compliance wrong and you’re facing regulatory exposure. Get the capacity wrong and you’re either rationing water during peak demand or paying for storage you don’t need. We’ve been delivering drinking water storage solutions to facilities across the UK for over 50 years, and the same questions come up every time. Here’s what matters.
Understanding WRAS Compliance for Potable Water Storage
WRAS stands for the Water Regulations Advisory Scheme. For anyone specifying potable water storage, WRAS approval is the baseline requirement, not an optional extra.
In the UK, potable water storage tanks must comply with the Water Supply (Water Fittings) Regulations 1999, which sets out the legal standards for any fitting, material, or product in contact with drinking water. Tanks also need to meet BS EN 13280, the British and European standard for glass fibre reinforced cisterns used in cold water storage. Using non-compliant storage puts you in direct breach of these regulations, and in a facility serving the public or a workforce, that’s a serious liability.
Our potable water tanks use a special grade of butyl rubber liner tested to BS 6920 standards and approved by WRAS, confirming it’s safe for contact with drinking water. The liner is also resistant to water treatment chemicals including chlorine, making it suitable for sterilisation in line with BS 6700.
How to Calculate the Storage Capacity Your Site Needs
Storage capacity needs to be sized around peak demand, not average demand. Average figures will leave you short precisely when it matters most.
As a general starting point, consider these typical daily consumption benchmarks:
- Offices: approximately 40 to 60 litres per person per day
- Hospitals: 350 litres or more per bed per day, depending on the type of facility
- Manufacturing sites: highly variable, but process water demand often runs well above standard occupancy figures, dependent on processes undertaken.
From there, you need to factor in your peak flow rate (the maximum demand across any given hour), your site’s supply reliability, and whether you need resilience against supply interruptions. For many facilities, holding 24 hours of peak demand capacity is a reasonable minimum. Sites with critical continuity requirements, hospitals being the obvious example, often specify significantly more.
The right number is specific to your site. Our technical team can work through the calculation with you based on your actual usage data and demand profile.
Tanks for Drinking Water Storage
The main water storage tank configurations we offer for potable applications is the Liquistore® cylindrical tank.
Liquistore® (cylindrical) tanks are site-assembled, which gives them a significant advantage on live operational sites where access is restricted. Components are brought to site in component form and assembled in place from the top down, using hydraulic lifting equipment. This removes working at height issues and the need for scaffolding or cranes.
Liquistore® tanks are WRAS approved and lined with butyl rubber or PVC, providing a fully impermeable seal that separates the stored water from the interior tank shell.
Site-Assembly Benefits for Operational Facilities
One of the most practical advantages of site-assembled tanks is that installation doesn’t require the facility to stop operating. Components are manageable in size, which means they can be manoeuvred through corridors, lift shafts, and plant room doors that would make a pre-fabricated tank impossible to install.
There’s no need for risky working at height, scaffolding or crane access, no requirement to remove roofing or structural elements, and no large vehicle presence on site. For a hospital, a food production facility, or any site where downtime carries a real cost, this matters considerably.
Installation is carried out by our own engineers, who understand the product inside out. Once the tank is assembled and commissioned, it’s ready to perform to the same standard as any factory-built alternative.
What Actually Matters Beyond Compliance and Capacity
Experienced facility managers know that a tank that meets compliance on day one still needs to perform ten or twenty years later. A few things are worth thinking through at the specification stage.
Maintenance access should be designed in from the start. Inspection hatches, access ladders, and adequate clearance around the tank make routine checks and liner inspections far less disruptive. Tanks that are difficult to access tend to get inspected less frequently, and that’s when problems develop unnoticed.
Liner condition is the most common issue we see in older tanks. Butyl rubber and EPDM liners are highly durable and can stretch up to 300% of their original size without losing their water-retaining properties, but they do need periodic inspection, as do PVC liners. Our tank survey service includes ROV underwater camera inspections that assess the interior without draining the tank, saving time and avoiding disruption to supply.
Refurbishment is often the right answer for tanks that are structurally sound but have a liner that’s past its best. It’s considerably more cost-effective than replacement and restores the tank to full performance.
Ready to Specify Potable Water Storage That Meets Your Site’s Needs?
Getting potable water storage right means understanding both compliance and capacity, then matching the right tank design to the realities of your site. Franklin Hodge has been doing exactly that for over 50 years, working with facility managers, project engineers, and construction teams across commercial and industrial sectors.
If you’re planning a new installation or reviewing an existing setup, get in touch with our technical team to discuss your specific site requirements.
