How to Store Drinking Water Long-Term Using the Right Tank and Liner
Access to safe drinking water is something most people in the UK take for granted. But whether you are preparing for an emergency, managing water supply for a remote site, or operating a large-scale commercial or industrial facility that cannot rely on mains supply alone, knowing how to store drinking water long-term safely is both a practical necessity and a legal obligation. Get the storage wrong and the water you are relying on becomes a health risk rather than a safe supply.
The good news is that storing drinking water long-term is straightforward when the right containers or tanks are used, the correct treatment is applied, and the storage conditions are maintained properly. For households and small sites, this means food-grade containers, correct chlorine treatment, and regular rotation. For commercial operators, farms, water utilities, and industrial facilities, it means correctly specified potable water storage tanks with WRAS-approved liner kits, compliant fittings, and a maintenance regime that keeps stored water safe to drink throughout its storage life.
This guide covers everything you need to know: how much water to store, which containers and tanks are suitable, what liner and material choices matter for long-term water quality, how to keep stored water safe, and what UK safety standards apply to commercial drinking water storage.
How Much Water Should You Store?
Before deciding how to store drinking water long-term, you need to know how much to store. The amount of water required depends entirely on the number of people relying on the supply and the duration of storage needed.
For emergency drinking water storage, the standard guidance from UK emergency planning bodies is to store at least one litre of water per person per day for drinking alone. When cooking, hygiene, and basic sanitation are included, the figure rises to between two and three litres per person per day as a minimum. For a family of four, at least a three-day supply means a minimum of 24 litres, though a two-week supply of around 112 litres provides significantly more resilience against prolonged supply disruption.
For commercial, agricultural, and industrial sites, the amount of water required is calculated against daily operational demand rather than per person per day. A food production facility, hospital, or agricultural operation may need tens of thousands of litres of stored potable water to maintain operations through a mains supply interruption. For these applications, water storage tanks sized from 2m3 to 5,000m3 provide the capacity needed to keep operations running regardless of supply disruption.
Choosing the Right Water Storage Container
The container or tank used to store drinking water long-term is the most important decision in the entire storage process. Not all containers are suitable and using the wrong material can contaminate the water with chemicals, bacteria, or taste compounds that make it unsafe or unpalatable to drink.
For small-scale domestic or emergency water storage, containers must be food-grade. Food-grade water storage containers are manufactured from materials that will not leach harmful chemicals into the stored water. Look for containers made from high-density polyethylene marked HDPE, polypropylene, or other food-safe plastics. Never use containers that previously held non-food substances such as chemicals, bleach, or fuel, even after cleaning. Commercially bottled water in its original sealed container is the most convenient way to store small volumes for emergency use, though it is more expensive and produces significant plastic waste.
For larger volumes, jerry cans and purpose-built water storage barrels in food-grade materials are suitable. When transferring water from one container to another, ensure the receiving container is clean and food-grade before filling.
For commercial, industrial, and large-scale agricultural applications, water storage containers of the scale required are corrugated steel tanks fitted with food-grade, WRAS-approved liner kits. These provide far greater capacity, structural integrity, and service life than any plastic container option and are the correct specification for any site storing potable water for operational use.
Tank Materials for Long-Term Drinking Water Storage
The material from which a water storage tank is constructed directly affects the long-term safety and quality of stored drinking water. Different tank materials have different advantages, limitations, and compliance requirements for potable water use.
Corrugated Steel Tanks
Corrugated steel tanks are the most widely used large-scale potable water storage solution in the UK, trusted by water utility companies, local authorities, NHS trusts, food production facilities, and industrial operators. The steel panels themselves do not contact the stored water directly. Instead, a WRAS-approved liner kit sits inside the tank and forms the watertight chamber that contacts the water. This separation of structure and liquid containment means the tank can be sized, configured, and relocated with complete flexibility, while the liner provides the food-grade, WRAS-compliant contact surface required for safe drinking water storage.
Butek Tanks' corrugated steel water storage tanks are available from 2m3 to 5,000m3 and are manufactured from Magnelis-coated or galvanised steel panels that provide exceptional corrosion resistance without any coating material contacting the stored water. Every tank is fitted with the appropriate liner kit for the stored liquid and the intended application.
GRP and Plastic Tanks
Glass reinforced plastic tanks and rotationally moulded polyethylene tanks are commonly used for smaller potable water storage applications. They are lightweight, easy to install, and available in a wide range of sizes. However their capacity is limited compared to corrugated steel systems, and larger GRP tanks are significantly more expensive per cubic metre of storage than corrugated steel alternatives. For sites requiring storage above approximately 50m3, corrugated steel tanks are almost always the more cost-effective specification.
Stainless Steel Tanks
Stainless steel tanks are used in food production and pharmaceutical applications where the highest hygiene standards are required. They are easy to clean and disinfect and have no liner requirement for most applications. However their capital cost is significantly higher than corrugated steel or GRP alternatives and they are generally not used for large-scale utility or agricultural water storage in the UK.
Liner Choice for Potable Water Tanks
For corrugated steel potable water tanks, the liner is the most critical component in determining long-term water safety and quality. The liner is the only material in direct contact with the stored drinking water, and it must be manufactured from materials that will not contaminate the water, will not support microbial growth, and will not degrade over the expected service life of the installation.
Butyl Rubber Liners
Butyl rubber is the standard liner material for potable water storage in corrugated steel tanks. It is WRAS-approved for drinking water contact, chemically inert, flexible enough to accommodate the slight movement of the steel panels under load, and has an exceptionally long service life. Butyl liners do not affect the taste or smell of stored water and do not leach chemicals into the stored supply over long-term storage periods.
EPDM Liners
EPDM is an alternative synthetic rubber liner material used in certain potable water applications. Like Butyl rubber, EPDM must carry WRAS approval for use in drinking water contact applications. It has good chemical resistance and UV stability for exposed installations.
WRAS Approval: Why It Matters
Any liner used in a UK mains-connected or potable water storage tank must carry WRAS approval under the Water Supply (Water Fittings) Regulations 1999. WRAS approval confirms that the liner material has been independently tested and proven safe for contact with drinking water. Using a non-approved liner in a potable water tank is a breach of the Water Fittings Regulations and could render the stored water unsafe to drink through chemical leaching or microbial contamination.
Our WRAS-approved liner kits are manufactured in-house from Butyl rubber and are the standard specification for every Butek Tanks potable water storage installation. Full roof kits are also available to prevent contamination from airborne particles, bird access, and UV-driven algal growth, all of which degrade water quality over long-term storage.
How to Keep Stored Water Safe to Drink
Choosing the right container or tank is only the first step. Keeping stored water safe to drink over a long storage period requires correct treatment, proper storage conditions, and a regular maintenance routine.
Chlorine Treatment
Tap water in the UK already contains a small amount of chlorine added during the treatment process to prevent bacterial growth. When water is stored long-term, this residual chlorine gradually dissipates, leaving the water vulnerable to bacterial contamination. For small-scale domestic emergency storage, adding unscented liquid chlorine bleach at a rate of approximately two drops of bleach per litre of water before sealing the container helps maintain a safe level of chlorine in the stored supply. Water purification tablets are an alternative and are available from camping supply stores and pharmacies across the UK.
For commercial and large-scale storage tanks, chlorination is managed as part of a planned maintenance and water quality programme, typically including periodic shock chlorination and regular sampling to verify that stored water remains safe to drink throughout the storage period.
Storage Conditions
Water stored long-term must be kept away from direct sunlight, which promotes algal growth and accelerates the breakdown of chlorine residual. Store containers and tanks in a cool, dark location where water temperature remains stable. High water temperatures accelerate bacterial growth and reduce the effectiveness of residual chlorine. On commercial sites, insulated or shaded tank installations help maintain appropriate storage temperatures year-round.
Keep stored water away from chemicals, fuels, and other substances whose vapours can permeate certain plastics and contaminate the water supply. For domestic storage, this means avoiding garages or outbuildings where petrol, paint, or solvents are stored.
Rotation and Replacement
For domestic emergency water storage, replace the water every six months to ensure freshness and maintain safe chlorine levels. Label containers with the date of filling and rotate your water supply on a first-in-first-out basis. When you replace the water, clean the container with soapy water, rinse thoroughly, and treat the fresh supply before resealing.
For commercial storage tanks, a planned rotation and inspection schedule is part of the WRAS compliance and Legionella risk management obligations that apply to all large-scale potable water installations.
UK Safety Standards for Drinking Water Storage
For commercial, industrial, and large-scale potable water storage in the UK, two sets of regulations govern how stored drinking water must be managed.
The Water Supply (Water Fittings) Regulations 1999 require that all fittings, tanks, liners, and components connected to or in contact with mains-supplied drinking water must be WRAS-approved. This applies to every element of a commercial potable water storage installation including the tank, the liner, the valves, and all connected fittings available through our accessories range.
ACoP L8, the Approved Code of Practice for the control of Legionella bacteria in water systems, places obligations on all commercial and industrial operators to assess, manage, and control the risk of Legionella growth in stored water systems. Legionella bacteria thrive in warm, stagnant water between 20 and 45 degrees Celsius. For large potable water storage tanks, this means managing water temperature, ensuring adequate turnover of stored water, maintaining residual chlorine levels, and carrying out regular inspection and cleaning of the tank interior and liner surface.
Professional installation services from Butek Tanks include full documentation of WRAS-compliant components and installation conditions, giving commercial operators the audit trail needed for regulatory and insurance purposes.
Frequently Asked Questions About Storing Drinking Water Long-Term
How long can you store drinking water safely?
Commercially bottled water in sealed, food-grade containers has a shelf life of at least two years when stored correctly. Tap water stored in clean, food-grade containers with appropriate chlorine treatment remains safe to drink for six months when kept away from direct sunlight and stored at a stable, cool temperature. For commercial storage tanks, the water quality must be monitored and maintained continuously as part of a planned Legionella risk management and WRAS compliance programme.
How much water should I store per person per day?
The minimum recommendation for emergency drinking water storage is one litre per person per day for drinking alone. Including cooking and hygiene raises the requirement to between two and three litres per person per day. For a family of four, a two-week emergency supply requires approximately 112 to 168 litres depending on usage assumptions.
Does stored water need to be treated with chlorine?
Yes, for long-term storage beyond a few days. Tap water contains residual chlorine that dissipates over time. Adding unscented chlorine bleach or water purification tablets before sealing stored water maintains a safe level of disinfection. For commercial storage tanks, chlorination is managed as part of a planned maintenance programme that includes regular water quality testing.
What containers are safe for storing drinking water long-term?
Containers must be food-grade and manufactured from materials that will not leach chemicals into the stored water. Suitable materials include HDPE, polypropylene, and other food-safe plastics for small volumes. For large-scale commercial storage, corrugated steel tanks fitted with WRAS-approved Butyl rubber liner kits are the correct specification and are trusted by water utilities, local authorities, and industrial operators across the UK.
What is WRAS approval and why does it matter for water storage tanks?
WRAS approval is the certification scheme confirming that a water fitting or material complies with the Water Supply (Water Fittings) Regulations 1999 and is safe for contact with drinking water. Any liner, tank fitting, or component in contact with mains-connected potable water in the UK must carry WRAS approval. Using non-approved materials can contaminate the stored water and constitutes a breach of the Water Fittings Regulations.
Need Long-Term Potable Water Storage? Butek Tanks Can Help
Whether you are specifying a new potable water storage system for a water utility, a food production facility, a remote industrial site, or an agricultural operation, Butek Tanks provides bespoke corrugated steel water storage tanks with WRAS-approved liner kits for every long-term drinking water storage application. As a specialist division of Butyl Products Ltd, we design, manufacture, and install corrugated steel storage systems for potable water, rainwater harvesting, irrigation, and a wide range of liquid storage applications across the UK and internationally. Our solutions are ISO 9001:2015 certified, CE marked, and deployable globally.
Get in touch today. Call us on +44 (0)1277 653 281 or email enquiries@butektanks.co.uk, or visit our contact page to submit your project requirements. Our team will respond promptly to discuss your needs.