What's the difference between mineral water and spring water?
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Part of our bottled and other water guide
Both labels point to water from the ground. In UK law they are separate things, and only one of them needs official recognition. You can see how a bottle compares with your own tap using a 20-in-1 test strip.
Short answer: Defra says natural mineral water needs official recognition, which can take up to 2 years, plus a stable composition and a composition label. Spring water needs none of those, though both come from a protected underground source and are bottled at the spring or borehole. A natural mineral water cannot be sold as spring water.
By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026
What is the difference between mineral water and spring water?
The difference is the approval the water needs and what it must demonstrate, not where it comes from. Defra's comparison of the 3 types of bottled water says both must come from an underground source tapped at a natural or drilled exit, be bottled at a spring or borehole, be free of disease-causing parasites and bacteria, and meet limits for chemical, microbial and radioactive substances. The guidance applies to England. We cover what a strip can and cannot show at the end.
| Defra's comparison | Natural mineral water | Spring water |
|---|---|---|
| Official recognition from the local authority | Required | Not required |
| Keeps its "original purity" from source to bottling | Required | Not required |
| Stable composition over a lengthy period | Required | Not required |
| Composition on the label | Required | Not required |
| Treatments permitted | 5 treatment types | Any |
The third type, bottled drinking water, does not have to come from an underground source, according to the same table. Our spring water guide covers spring water on its own in more detail. For Wales and Northern Ireland, Defra points to Food Standards Agency guidance, and for Scotland to Food Standards Scotland. We did not read either, so this guide covers England.
Does "mineral" mean a set amount of minerals?
Not in the sources we read, which set no minimum amount. What the water must show is a stable composition and original purity, meaning its properties have stayed the same from source to bottling without contamination, and it must state that composition on the label. Defra's guidance for local authorities lets a label use set wording if the numbers qualify.
| Wording a label may use | Defra's criterion |
|---|---|
| Very low mineral content | Fixed residue of 50 mg/l or less |
| Low mineral content | Fixed residue of 500 mg/l or less |
| Rich in mineral salts | Fixed residue of 1500 mg/l or more |
| Contains bicarbonate | 600 mg/l or more |
| Contains calcium | 150 mg/l or more |
| Contains magnesium | More than 50 mg/l |
Our reading is that a recognised natural mineral water can be low in minerals, because "very low mineral content" is open to a water at 50 mg/l or less. If you want a rough hardness figure to set beside a label's calcium figure, our hardness testing guide shows how the hardness pad on our 20-in-1 strip works.
How does a water become a natural mineral water?
Slowly. Defra's guide for producers in England says recognition can take up to 2 years. The producer needs a water abstraction licence from the Environment Agency, then gathers 2 years of evidence for the local authority. That includes geological and hydrological surveys, monthly records of the spring's flow, temperature, dry residues at 180°C and 260°C and electrical conductivity, and tests every 3 months for anions, cations and trace elements. The pH is recorded once.
Defra's rules for local authorities say levels must not change by more than 20% from the first test. The local authority grants recognition in writing, publishes it in the London Gazette, and Defra adds the water to its list of recognised natural mineral waters. After that the authority checks at least once a year that the composition stays stable and the labelling is correct.
These are the maximums Defra gives for substances naturally present in a natural mineral water at source. They are legal ceilings, not typical levels.
| Substance | Maximum (mg/l) |
|---|---|
| Nitrate | 50 |
| Nitrite | 0.1 |
| Copper | 1.0 |
| Manganese | 0.50 |
| Fluoride | 5.0, with a label statement above 1.5 |
| Lead | 0.010 |
We found no matching list for spring water in the Defra pages we read, which say only that it must meet limits.
Can mineral and spring water be treated, and can they be fizzy?
Natural mineral water has a closed list and spring water does not. Defra allows natural mineral water 5 treatments only. These are filtration or decanting, removing free carbon dioxide, adding or re-adding carbon dioxide, ozone-enriched air oxidation and activated alumina. The last two need the local authority's authorisation. Defra says disinfection is not permitted. Its comparison table lists "any" for spring water.
A fizzy natural mineral water must use one of 3 sales descriptions.
- Naturally carbonated natural mineral water. The gas content after bottling is the same as at source.
- Natural mineral water fortified with gas from the spring. The content is higher than at source, using gas from the same spring.
- Carbonated natural mineral water. The gas was added from another source.
Why might your own tap not match what a bottle label says?
A label describes one spring at its source. A figure for a spring or for your area does not tell you what comes out of your own tap. The Defra pages we read cover bottled water only, so they give no tap figures. What they do show is how much a label commits to. A natural mineral water must state its composition and keep it stable. Spring water and bottled drinking water have no composition-label requirement in Defra's comparison, and bottled drinking water need not come from an underground source, which is why people ask whether bottled water is just tap water.
“A bottle label describes the spring it came from, but your kitchen tap has no label at all, so I would not assume the two match. If you're curious, test the bottle and the tap with the same strip on the same day and compare.”
Putting a bottle and your own tap side by side takes a reading from each, and the next section shows what the strip can and cannot compare.
How can you check a bottle against your own tap?
With the WaterKit 20-in-1 strip, you fill a clean glass with each water, dip a strip, wait 30 to 60 seconds and match the pads to the chart. You can also enter the colours in our free results checker, which opens in the browser with no app or account. We have not run strips on bottles of mineral or spring water, so the right-hand column is our own reading of the chart steps, not results.
| On the label or in Defra's rules | What our chart can show |
|---|---|
| Calcium and magnesium in mg/l | The hardness pad has steps at 0, 25, 50, 100, 250 and 425 and gives one band, with its unit basis unconfirmed, so treat any match as rough |
| Bicarbonate (600 mg/l or more for the label wording) | The alkalinity pad's top step is 240, below the 600 mg/l label figure, so it cannot show whether a water reaches that wording, and its unit basis is unconfirmed |
| Nitrate (maximum 50 mg/l) | A reading of 25 or below indicates under the limit, 50 at or near it, and 100 or more above it |
| Copper (1.0 mg/l) and manganese (0.50 mg/l) | Copper steps at 0.2, 0.5, 1, 2 and 5 mg/l. Manganese steps at 0.05, 0.1, 0.5, 1, 2 and 5 mg/l |
Several things are outside what the kit can do.
- We do not claim the rapid bacteria test for bottled water. It is a presence screen for tap and private supply samples.
- The lead pad's first step is 20 and the nitrite pad's is 1, far above the 0.010 and 0.1 mg/l limits in the table above, and the fluoride pad's first step of 4 is above the 1.5 mg/l label threshold. We do not claim the strip reads iron, mercury, chromium or aluminium at UK limits either, so a clear result on any of these pads is not a pass. The strip cannot read lead at the UK limit, and our lead pipes guide covers your own plumbing instead.
- It does not read the fixed residue behind "low mineral content", and a strip result has no legal effect.
Best pack: 20 strips, enough to test your tap and a few bottles side by side and again later, £5.99 (or £10.99 with a bacteria test for the tap), with free 2nd Class delivery on every order. See the kit
Your mineral and spring water questions
What is mineral water? What is natural mineral water?
Defra's term is natural mineral water. It comes from a protected underground source tapped at a natural or drilled exit, has official recognition and a stable composition, and states its composition on the label.
Is spring water the same as mineral water? Is mineral water the same as spring water?
No. Defra treats them as separate types. A recognised natural mineral water cannot be sold as spring water, and a producer who wants to switch needs local authority approval and must have the recognition withdrawn.
Is mineral water better than tap water? Is mineral water better than spring water?
We found no ranking in the sources we read. Defra describes what each bottled type must show, and our tap versus bottled water guide covers tap against bottled.
Is tap water mineral water? Is mineral water tap water?
No, in the sources we read. Defra's recognition process is for water from a spring or borehole that is bottled, and nothing we read describes tap water as natural mineral water.
Where does mineral water come from?
From an underground source tapped at a natural or drilled exit and bottled there, according to Defra. The label must give the spring's name and the place where it is exploited.
Is mineral water carbonated? Is mineral water naturally carbonated?
Not necessarily. Only "naturally carbonated natural mineral water" on the label means the gas content after bottling is the same as at the source.
Is mineral water distilled? Is mineral water the same as distilled water?
No. Distillation is not among the 5 treatments Defra lists, and it says any other treatments are not allowed. Our distilled water guide explains how distilled water differs.
Is mineral water pure?
The law's phrase is "original purity", meaning properties that stay the same from source to bottling without contamination. It does not mean free of minerals, which the composition label lists.
What is the pH of mineral water?
We found no typical figure in the sources we read. Producers record pH once while seeking recognition, and it is not among the items Defra says the label must carry.
Can you boil mineral water?
We found no UK official guidance on boiling mineral water in the sources we read.
How is mineral water made? How to make mineral water at home?
It is not made. It is collected from a recognised source and bottled there, using only the permitted treatments. We found no official home method in the sources we read.
Is mineral water filtered?
It can be. Defra allows natural mineral water to be filtered or decanted to separate iron, manganese and sulphur, with no label wording needed. Its table lists "any" treatment for spring water.
Sources
- Defra, Compare types of bottled water (published 28 May 2020; applies to England; the comparison table; read 29 October 2026).
- Defra, Natural mineral water: rules for local authorities (last updated 9 April 2026; recognition steps, 20% stability, London Gazette, 5 treatments, no disinfection, fizzy descriptions, optional label wording, naturally present limits, annual checks; its ongoing-checks table lists nitrate as 5 mg/l, which conflicts with 50 mg/l in its recognition table and in source 3, so we used 50; read 29 October 2026).
- Defra, Natural mineral water: how to produce and label in England (last updated 29 June 2026; up to 2 years to get recognition, abstraction licence, 2 years of data, pH recorded once, labelling; read 29 October 2026).
- WaterKit, Water Test Kit (20-in-1 strip, 30 to 60 second read, optional rapid coliform test read after 24 to 48 hours, 20 strips £5.99 or £10.99 with a bacteria test, free 2nd Class delivery on every order) and results portal. The strip-chart column and the comments on expected readings are WaterKit's own reading of the colour chart steps.
Contains public sector information licensed under the Open Government Licence v3.0.