Tap water in GL8, CotswoldSafe to drink.Very hard.
Supplied by Severn Trent. 49 samples, 20 substances, latest on 23 December 2025. Everything is inside the legal limit, and nothing comes close to it.
9.5 / 10
The tank is as full as the score. The specks are the minerals that make water hard.
What to do about it
Hard water: compare softener quotes
At 281 mg/L a softener is the only thing that stops limescale. Filters do not soften water.
It pays for itself in most homes at this hardness, through a boiler that stays efficient and appliances that last.
ZeroWater 12-Cup Ready-Pour
£40typical price
Households concerned about PFAS and heavy metals
Waterdrop 10UA Under Sink
£70typical price
High-volume under-sink filtration without RO complexity
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What's in a glass of GL8 water
Every bubble is a substance the lab measured. The higher it floats, the closer it came to its legal limit, the dashed line at the top.
Nitrate came closest to a limit, at 36% of it. 16 of 17 substances used under a quarter of theirs.
- Nitrate36%
- Aluminium11%
- Lead9%
- Fluoride6%
- Nickel5%
- Trihalomethanes5%
- Colour4%
- Iron3%
- Turbidity3%
- Arsenic2%
- Copper2%
- Manganese1%
- Antimony1%
- Chromium<1%
- Nitrite<1%
- Selenium<1%
- Cadmium<1%
- pH 7.54 pH
- Conductivity 480 µS/cm
- Phosphate 0.012 mg/L
All 20 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Aluminium | 0.021 mg/L | 0.2 mg/L | 11% |
| Colour | 0.8 mg/L Pt/Co | 20 mg/L Pt/Co | 4% |
| Turbidity | 0.12 NTU | 4 NTU | 3% |
| Iron | 0.007 mg/L | 0.2 mg/L | 3% |
| Manganese | 0.00073 mg/L | 0.05 mg/L | 1% |
| Copper | 0.0326 mg/L | 2 mg/L | 2% |
| Fluoride | 0.09 mg/L | 1.5 mg/L | 6% |
| Arsenic | 0.00019 mg/L | 0.01 mg/L | 2% |
| Cadmium | 0.00002 mg/L | 0.005 mg/L | <1% |
| Chromium | 0.00042 mg/L | 0.05 mg/L | <1% |
| Nickel | 0.001 mg/L | 0.02 mg/L | 5% |
| Lead | 0.00091 mg/L | 0.01 mg/L | 9% |
| Antimony | 0.000059 mg/L | 0.005 mg/L | 1% |
| Selenium | 0.00017 mg/L | 0.04 mg/L | <1% |
| pH | 7.54 pH | No legal limit | – |
| Nitrate | 18 mg/L | 50 mg/L | 36% |
| Nitrite | 0.003 mg/L | 0.5 mg/L | <1% |
| Conductivity | 480 µS/cm | No legal limit | – |
| Trihalomethanes | 0.00472 mg/L | 0.1 mg/L | 5% |
| Phosphate | 0.012 mg/L | No legal limit | – |
281mg of limescale minerals in every litre
This is the water that furs up kettles
Very hard on the UK scale. It is fine to drink. It is hard on boilers, showers, skin and anything that heats water, and a jug or tap filter will not change that.
Softener quotes for GL8
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Your river is the Tetbury Avon - source to conf unnamed trib, rated moderate
The Environment Agency rated the Tetbury Avon - source to conf unnamed trib as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by dissolved oxygen. It fails the chemical test, as every river, estuary and stretch of coast in England does, because of long-lasting pollutants such as mercury, PFOS (a forever chemical) and old flame retardants.
None of this is a test of your tap water. Environment Agency record · River health across England
GL8 in short
Tap water in GL8 (Cotswold) is supplied by Severn Trent in the Cotswold Central zone and scores 9.5 out of 10, against an England and Wales average of 9.0. None of the 20 tested substances came close to a limit. The latest sample is from 23 December 2025.
- 4th cleanest of 5 areas tested in Cotswold1 area in Cotswold scored lower. The best is GL56 on 9.6.
- Very hard water at 281 mg/LThe threshold for very hard is 250 mg/L. Expect visible limescale on taps and in kettles in GL8. How hardness is measured
- Nothing tested came within 40% of its legal limitThe highest was Nitrate at 36% of the 50 mg/L maximum. See every reading
Questions about GL8 water
Is GL8 tap water safe to drink?
Based on the latest tests, GL8 (Cotswold) water scores 9.5/10, which is safe. 0 of 20 tested contaminants exceeded recommended levels. Water is supplied by Severn Trent.
What contaminants are in GL8 water?
We tested 20 contaminants in GL8 water. None exceeded recommended safe levels.
Who supplies water in GL8?
GL8 (Cotswold) is supplied by Severn Trent. You can view their full profile and compliance data on our supplier page.
Is GL8 water hard or soft?
Water in GL8 (Cotswold) has a hardness of 281 mg/L CaCO3, which is classified as very hard. Hard water can cause limescale buildup. A water softener or filter jug may help.
Should I use a water filter in GL8?
GL8 water scored 9.5/10 with no contaminants above recommended levels. A filter is optional but can improve taste, especially if you notice a chlorine flavour. See our filter recommendations for your area.
Are there PFAS forever chemicals in GL8 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for GL8, and the Environment Agency has no PFAS detections in rivers or groundwater within 10 km of it. That reflects where sampling has happened as much as the water itself.
How clean is the river near GL8?
The Environment Agency rated the Tetbury Avon - source to conf unnamed trib as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by dissolved oxygen. It fails the chemical test, as every river, estuary and stretch of coast in England does, because of long-lasting pollutants such as mercury, PFOS (a forever chemical) and old flame retardants. This is a rating of the river, not of tap water in GL8, which is treated before it reaches homes.
Keep reading
- Best Water Softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared, with real costs
- Do I Need a Water Softener?The hardness bands, the symptoms, and a postcode check
- UK Water Hardness MapIs your water hard or soft, and does it matter?
- Is UK Tap Water Safe?Everything you need to know about tap water safety in the UK
- Do I need a water softener?The hardness bands, the symptoms, and when the answer is no
- Best water softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared
- Water softener costUnit, fitting and salt, and how long the payback takes
- Installation explainedWhere it goes, the bypass tap, the drain, DIY or plumber
- Harvey vs KineticoThe two premium twin-cylinder brands, side by side
- Softener salt guideTablet, block or granular, and how much you get through
- Salt-free softenersConditioners and electronic descalers, honestly assessed
How to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near GL8
Environment Agency samples from rivers, groundwater and reservoirs nearby. Not your tap water. For scale they are shown against drinking water limits; rivers are judged against much stricter environmental standards, and on those every river in England fails for chemicals.
Get alerts for your area
We'll email you when water quality data changes for GL8.