Tap water in CO11, TendringSafe to drink.Very hard.
Supplied by Anglian Water. 94 samples, 6 substances, latest on 2 December 2024. Everything is inside the legal limit, and nothing comes close to it.
9.7 / 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 312 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 CO11 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.
Iron came closest to a limit, at 11% of it. 4 of 4 substances used under a quarter of theirs.
- Iron11%
- Aluminium6%
- Manganese6%
- Turbidity5%
- Coliform Bacteria none found
- E. coli none found
312mg 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 CO11
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Your estuary is the Stour (Essex), rated moderate
The Environment Agency rated the Stour (Essex) as moderate for ecological health in its 2025 assessment, meaning the estuary is noticeably changed by pollution or engineering. It is held back by nitrogen, seagrass and saltmarsh and seaweed. 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
3
forever-chemical detections in nearby rivers and groundwater
At 1 site. The highest was PFBA at 0.0016 µg/L, at Grange Caravan Park, East End Spring, 4.6 km away, in October 2024. These are river and borehole samples, not tests of your tap water.
Every PFAS sample around Ipswich · Which filters remove PFAS · PFAS explained
CO11 in short
Tap water in CO11 (Tendring) is supplied by Anglian Water in the Tendring Central zone and scores 9.7 out of 10, against an England and Wales average of 9.0. None of the 6 tested substances came close to a limit. The latest sample is from 2 December 2024.
- The cleanest tap water of the 7 areas tested in TendringCO11 scores 9.7 out of 10, ahead of CO7 in second place on 9.1.
- Among the hardest water in the country at 312 mg/LVery hard starts at 250 mg/L. At this level kettles scale up within weeks and a softener is a normal purchase in CO11. How hardness is measured
- Scores higher than all 6 neighbouring districtsThe nearest rival is CO7 on 9.1, against 9.7 here. Compare with CO7
Questions about CO11 water
Is CO11 tap water safe to drink?
Based on the latest tests, CO11 (Tendring) water scores 9.7/10, which is safe. 0 of 6 tested contaminants exceeded recommended levels. Water is supplied by Anglian Water.
What contaminants are in CO11 water?
We tested 6 contaminants in CO11 water. None exceeded recommended safe levels. PFAS (forever chemicals) were also measured in rivers and groundwater within 10 km, though not in the tap-water tests themselves.
Who supplies water in CO11?
CO11 (Tendring) is supplied by Anglian Water. You can view their full profile and compliance data on our supplier page.
Is CO11 water hard or soft?
Water in CO11 (Tendring) has a hardness of 312 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 CO11?
CO11 water scored 9.7/10 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 CO11 water?
The tap-water tests we hold for CO11 do not include a PFAS result. Environment Agency monitoring found PFAS in 3 river and groundwater samples from 1 sites within 10 km of CO11, the highest being PFBA at 0.0016 µg/L about 4.6 km away. These are environmental samples, not tests of tap water. The UK currently has no legal limit for PFAS in drinking water; the Drinking Water Inspectorate uses a 0.1 µg/L guideline for individual compounds. Reverse osmosis filters can reduce PFAS levels.
How clean is the estuary near CO11?
The Environment Agency rated the Stour (Essex) as moderate for ecological health in its 2025 assessment, meaning the estuary is noticeably changed by pollution or engineering. It is held back by nitrogen, seagrass and saltmarsh and seaweed. 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 estuary, not of tap water in CO11, which is treated before it reaches homes.
Keep reading
- Best Filter for PFAS RemovalThe filters with independent certification to remove forever chemicals
- PFAS Forever ChemicalsWhat PFAS are and how to reduce your exposure at home
- 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?
- 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
PFAS explainedHow to test your waterBest water filtersFilter shower headsWater testing kitsUK water rankingsWater hardness checkerWater hardness map
River and groundwater readings near CO11
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.
| Substance | Reading | Drinking water limit |
|---|---|---|
| Boron | 1.4 mg/L | 1 mg/L |
| pH | 8.53 pH | None |
| Temperature | 15.2 °C | None |
| Conductivity | 1482 µS/cm | None |
| Nitrate | 12 mg/L | 50 mg/L |
| Nitrite | 0.045 mg/L | 0.5 mg/L |
| Phosphate | 0.65 mg/L | None |
| Dissolved Oxygen | 9.51 mg/L | None |
| Nickel | 0.00025 mg/L | 0.02 mg/L |
| Manganese | 0.005 mg/L | 0.05 mg/L |
| Copper | 0.0002 mg/L | 2 mg/L |
| Zinc | 0.0084 mg/L | None |
| Iron | 0.035 mg/L | 0.2 mg/L |
Get alerts for your area
We'll email you when water quality data changes for CO11.