What is Potable Water? UK Drinking Water Standards, Safe Storage and Water Tank Solutions
Potable water is water that is safe to drink, safe to cook with, and suitable for human consumption without posing any risk to health. Drinking water is essential to life, business, and compliance, yet the distinction between potable and non-potable water is widely misunderstood. Whether you manage a farm, run an industrial site, or work within the UK water industry, getting this distinction right is both a legal and operational necessity.
At Butek Tanks, we have manufactured corrugated steel water tanks for potable and non-potable water storage since 1965. From WRAS-approved liner kits to protective roof kits, our bespoke Steel Water Tanks are trusted by water utilities, farms, and industry across the UK. In this guide, we explain everything you need to know about potable water, from definition to safe storage.
What is Potable Water?
Potable water is water that has been treated, tested, and verified against national standards to make it safe for human consumption. Also known as drinking water, potable water is used for far more than hydration. Any application where water comes into direct contact with people, food, or surfaces used in food preparation requires water that is safe to drink.
For water to be considered potable, it must meet strict quality criteria covering freedom from harmful bacteria, viruses, and pathogens; safe concentrations of chemicals including nitrates, lead, and chlorine; absence of heavy metals and industrial pollutants; and an acceptable appearance, taste, and odour.
Water that has not been treated to this standard is classified as non-potable water and must never be used for drinking or cooking. Understanding the distinction between potable and non-potable water is fundamental to public health, water management, and regulatory compliance.
What is Non-Potable Water?
Non-potable water is water that is not safe to drink and must not be used for cooking, personal hygiene, or any purpose where it may be ingested. Non-potable water is commonly used across agriculture, construction, horticulture, and industry, and this is entirely legal provided it is clearly labelled and never cross-connected to a potable water system.
Common non-potable water sources include surface water from rivers and streams, ground water extracted without treatment, raw water before it enters a treatment process, reclaimed water from wastewater processes, rainwater collected from roofs and hard surfaces, and washing machine water recycling systems.
Typical uses of non-potable water include agricultural irrigation, toilet flushing in commercial buildings, industrial cooling systems, construction dust suppression, vehicle washing, and horticulture. Non-potable water is commonly used across all of these sectors, providing a cost-effective and sustainable alternative to mains supply for tasks that do not require drinking water quality.
In all cases, potable water and non-potable water must be stored separately and clearly labelled to prevent any risk of water contamination. Cross-connection between the two is one of the most serious risks in any water system.
Potable vs Non-Potable Water: Key Differences
Understanding the difference between potable and non-potable water protects public health and ensures you meet your legal obligations. Here is a clear summary:
Potable water: treated to DWI and WRAS standards, safe for human consumption, used for drinking, cooking, and hygiene, stored in a WRAS-approved potable water tank, sourced from municipal water supplies or treated ground water.
Non-potable water: untreated or partially treated, not safe to drink, used for irrigation, cleaning, and industrial applications, stored in clearly labelled non-potable tanks, sourced from surface water, rainwater, or reclaimed water.
Water contamination is the central risk when the two types are confused or cross-connected. Consuming water that is not safe to drink can cause serious gastrointestinal illness, infection, and in severe cases life-threatening conditions. This is why understanding the distinction between potable and non-potable water is so important, particularly for operators managing multiple water sources on a single site.
UK Drinking Water Standards and Regulations
The UK has one of the most rigorous regulatory frameworks for drinking water quality in the world. Drinking water is essential to public health and the regulatory bodies governing it reflect that.
Drinking Water Inspectorate (DWI)
The DWI is the independent regulator responsible for ensuring public water supplies meet required drinking water standards in England and Wales. It enforces the Water Supply (Water Quality) Regulations 2016, covering over 50 parameters including bacteriological tests, chemical concentrations, and physical properties. Water companies must carry out regular water testing, maintain detailed records, and report results to the DWI. The regulations define exactly what parameters treated water must meet before it is distributed as safe drinking water.
WRAS Compliance for Water Storage
For any business storing or distributing potable water, WRAS (Water Regulations Advisory Scheme) compliance is essential. Any potable water tank or fitting connected to the mains supply must be WRAS-approved to ensure the materials used will not cause water contamination. WRAS approval is a legal requirement under the Water Supply (Water Fittings) Regulations 1999, not an optional standard.
Private Water Supplies
Properties relying on private water supplies, such as rural farms and remote industrial sites, are governed by the Private Water Supplies (England) Regulations 2016. These require regular potable water testing and risk assessments, ensuring the water meets the same drinking water standards as municipal water supplied by water utilities. Potable water testing for private supplies is the responsibility of the landowner or site operator, not the water company.
How is Potable Water Treated?
All raw water, regardless of source, must go through a water treatment process before it is considered safe to drink. The typical stages of the treatment process are:
Screening: removal of large debris and solids from the raw water intake.
Coagulation and flocculation: chemicals cause fine particles to clump together for easier removal.
Sedimentation: heavier particles settle to the bottom of settlement tanks.
Filtration: water passes through sand or carbon filters to remove bacteria and organic matter.
Disinfection: chlorination or UV treatment destroys remaining pathogens, making the water safe for human consumption.
pH adjustment: chemical dosing balances pH to prevent pipe corrosion and protect water quality.
Water testing: final samples are tested across all required parameters before distribution.
Water treatment systems range from large municipal plants serving millions of people to compact on-site treatment systems for farms and remote sites. For sites that need a complete, deployable sewage and wastewater treatment solution, Butek Tanks' Modular Wastewater System (MWS) can be installed in as little as 14 days, processes up to 1,000m3 per day, and produces 99.99% pathogen-free treated water.
Potable Water Storage: Choosing the Right Water Tank
If your operation stores water for human consumption, livestock welfare, food production, or any application requiring drinking water quality, you need a dedicated potable water tank. Drinking water is essential on every operational site and safe storage is not optional.
A compliant potable water tank must be constructed from non-leaching, food-safe materials that will not contaminate stored water; WRAS-approved and compliant with UK water supply regulations; sealed to prevent ingress of dust, debris, insects, and wildlife; fitted with a liner appropriate for the liquid being stored; and regularly inspected, cleaned, and maintained to prevent biofilm and Legionella risk.
Why Plastic Water Tanks Fall Short
Plastic water tanks are low-cost but come with real limitations for large-scale potable water storage. Certain plastics can leach gases and chemicals into stored water over time, particularly under UV exposure or temperature changes. Porous surfaces in lower-grade plastic water tanks can harbour bacteria and biofilm. For long-term, high-volume, or industrial-grade potable water storage, corrugated steel tanks with a WRAS-approved liner are the preferred solution across the UK water industry.
Butek Tanks Corrugated Steel Water Tanks
Butek Tanks manufactures the UK's largest range of corrugated steel water tanks, with capacities from 2m3 to 5,000m3. Made from Magnelis coated steel for superior corrosion resistance, each tank can be configured with the appropriate liner for potable compliance. Our Liner Kits include:
Butyl Rubber: the premier potable water liner with exceptional impermeability and fully vulcanised factory seams, ideal for long-term potable water storage.
EPDM Rubber: a cost-effective rubber option with good flexibility, suitable where maximum longevity is not the primary requirement.
HDPE: the industry standard in aquaculture and fish farming, and ideal where frequent internal cleaning is required.
PVC: a versatile, cost-effective option available in a wide range of specifications, suitable for both potable and non-potable applications.
Covering your potable water tank is equally important for maintaining water quality. Open-top tanks are vulnerable to contamination from dust, debris, algae growth, and insects. Butek Tanks offers a full range of Roof Kits from heavy-duty steel roofs designed to withstand extreme weather loading, to the Aqua-Float floating cover that prevents up to 98% of evaporation, all with lockable access hatches for authorised inspection.
For agricultural operations that also need to manage slurry and organic waste streams alongside water storage, our Slurry Tanks provide high-capacity, structurally certified storage from 280m3 to 1,250m3, certified to British and European structural standards.
Is Rainwater Considered Potable?
Not by default. Rainwater collected from roofs or hard surfaces picks up contaminants and is non-potable in its raw state. It can be treated and tested to meet drinking water standards, but requires appropriate filtration, disinfection, and potable water testing before it is suitable for drinking.
For most UK farms and businesses, harvested rainwater is used as non-potable water for irrigation, toilet flushing, and vehicle washing, reducing reliance on mains water supplies without the cost and complexity of treating it to drinking water standard. Rainwater harvesting for non-potable use is one of the most effective and sustainable water management strategies available to UK businesses today.
Indirect Potable Reuse: The Future of Water Resources?
Indirect potable reuse is a process where highly treated wastewater or reclaimed water is returned to a natural water body such as a river or aquifer, where it mixes with existing water resources. It is later extracted and treated again to drinking water standard before it is distributed as potable water.
This approach is increasingly being explored by UK water companies as water resources come under pressure from climate change and population growth. It represents a significant development in sustainable water management and highlights how the boundary between reclaimed water and considered potable water is becoming increasingly sophisticated in the modern water industry.
Frequently Asked Questions About Potable Water
Is tap water potable in the UK?
Yes. UK tap water is considered potable and consistently meets DWI drinking water standards. Tap water and bottled water are both subject to strict quality water regulations in the UK, and municipal water supplied by water utilities is tested thousands of times annually. Tap water is among the safest in the world.
What is the difference between potable and non-potable water?
Potable water is water that is safe to drink and has been treated to meet UK drinking water standards. Non-potable water is water that is not safe to drink, either because it has not been treated or because it does not meet the required quality standards. The key practical difference is in storage, labelling, and permitted use. Potable water must be stored in a WRAS-approved potable water tank; non-potable water must be clearly labelled and kept separate from potable supplies at all times.
Do I need a WRAS-approved tank to provide potable water on site?
Yes. Any tank connected to the mains supply and used to store potable water in the UK must comply with WRAS requirements under drinking water regulations. This ensures the materials used in tank construction and lining will not contaminate the water stored. Butek Tanks' corrugated steel water tanks, fitted with WRAS-approved liner kits, are fully compliant and trusted by water companies, farms, and industrial operators across the UK.
Can non-potable water make you ill?
Yes. Water that is not safe to drink can cause serious gastrointestinal illness, infection, and in severe cases life-threatening conditions. Water contamination from non-potable sources is a significant public health risk, which is why potable and non-potable water must always be clearly identified, stored separately, and protected from cross-contamination.
What is pure water?
Pure water refers to water that contains no dissolved minerals, chemicals, or contaminants whatsoever, typically produced through distillation or deionisation. It is not the same as potable water. In fact, pure water is not recommended for regular drinking as it lacks the beneficial minerals found in safe drinking water and can cause mineral imbalances if consumed in large quantities.
Conclusion
Potable water is water that is safe for human consumption and has been treated and tested to meet strict UK drinking water standards. Non-potable water is water that is not safe to drink but has many legitimate uses across agriculture, industry, and construction. Understanding the distinction between potable and non-potable water, how the UK treatment process works, and how to store water safely and compliantly is critical for any operator across the water industry, agriculture, or industrial sectors.
With over 60 years of experience, Butek Tanks provides bespoke steel water tanks with a full range of liner kits and roof kits to meet every potable and non-potable water storage requirement. From 2m3 to 5,000m3, our ISO 9001:2015 certified, CE-marked tanks are trusted by water companies, farms, and industry across the UK and beyond. Need a bespoke potable water tank solution? Contact Butek Tanks today to discuss your water storage requirements. Our team will tailor a solution from concept to completion.