Tap water in CM11, BasildonSafe to drink.Very hard.
Supplied by Essex & Suffolk Water. 2,911 samples, 21 substances, latest on 19 December 2025. Everything is inside the legal limit, and nothing comes close to it.
9.3 / 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 310 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 CM11 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 38% of it. 18 of 19 substances used under a quarter of theirs.
- Nitrate38%
- Fluoride17%
- Nickel11%
- Arsenic9%
- Colour7%
- Aluminium6%
- Boron6%
- Antimony5%
- Bromate5%
- Iron4%
- Turbidity3%
- Copper3%
- Mercury2%
- Selenium2%
- Chromium1%
- Nitrite1%
- Lead<1%
- Manganese<1%
- Cadmium<1%
- Conductivity 620 µS/cm
- pH 7.6 pH
All 21 results as a table
| Substance | Result | Legal limit | Share of limit |
|---|---|---|---|
| Nitrate | 19 mg/L | 50 mg/L | 38% |
| Conductivity | 620 µS/cm | No legal limit | – |
| Nitrite | 0.0065 mg/L | 0.5 mg/L | 1% |
| pH | 7.6 pH | No legal limit | – |
| Iron | 0.0078 mg/L | 0.2 mg/L | 4% |
| Manganese | 0.00028 mg/L | 0.05 mg/L | <1% |
| Colour | 1.4 mg/L Pt/Co | 20 mg/L Pt/Co | 7% |
| Turbidity | 0.12 NTU | 4 NTU | 3% |
| Aluminium | 0.012 mg/L | 0.2 mg/L | 6% |
| Copper | 0.05 mg/L | 2 mg/L | 3% |
| Arsenic | 0.00089 mg/L | 0.01 mg/L | 9% |
| Bromate | 0.0005 mg/L | 0.01 mg/L | 5% |
| Chromium | 0.00067 mg/L | 0.05 mg/L | 1% |
| Lead | 0.000065 mg/L | 0.01 mg/L | <1% |
| Selenium | 0.00083 mg/L | 0.04 mg/L | 2% |
| Cadmium | 0.000018 mg/L | 0.005 mg/L | <1% |
| Nickel | 0.0022 mg/L | 0.02 mg/L | 11% |
| Antimony | 0.00027 mg/L | 0.005 mg/L | 5% |
| Fluoride | 0.26 mg/L | 1.5 mg/L | 17% |
| Mercury | 0.000022 mg/L | 0.001 mg/L | 2% |
| Boron | 0.06 mg/L | 1 mg/L | 6% |
310mg 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 CM11
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Your river is the Crouch (A129 - Wickford), rated moderate
The Environment Agency rated the Crouch (A129 - Wickford) as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by phosphate, insects and other small river life and ammonia. 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
CM11 in short
Tap water in CM11 (Basildon) is supplied by Essex & Suffolk Water in the Basildon Central zone and scores 9.3 out of 10, against an England and Wales average of 9.0. None of the 21 tested substances came close to a limit. The latest sample is from 19 December 2025.
- Among the hardest water in the country at 310 mg/LVery hard starts at 250 mg/L. At this level kettles scale up within weeks and a softener is a normal purchase in CM11. How hardness is measured
- 3rd cleanest of 8 areas tested in BasildonOnly 2 areas in Basildon scored higher. The best is SS13 on 9.4.
- Nothing tested came within 40% of its legal limitThe highest was Nitrate at 38% of the 50 mg/L maximum. See every reading
Questions about CM11 water
Is CM11 tap water safe to drink?
Based on the latest tests, CM11 (Basildon) water scores 9.3/10, which is safe. 0 of 21 tested contaminants exceeded recommended levels. Water is supplied by Essex & Suffolk Water.
What contaminants are in CM11 water?
We tested 21 contaminants in CM11 water. None exceeded recommended safe levels.
Who supplies water in CM11?
CM11 (Basildon) is supplied by Essex & Suffolk Water. You can view their full profile and compliance data on our supplier page.
Is CM11 water hard or soft?
Water in CM11 (Basildon) has a hardness of 310 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 CM11?
CM11 water scored 9.3/10 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 CM11 water?
No PFAS (forever chemicals) result is attached to the tap-water tests for CM11, 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 CM11?
The Environment Agency rated the Crouch (A129 - Wickford) as moderate for ecological health in its 2025 assessment, meaning the river is noticeably changed by pollution or engineering. It is held back by phosphate, insects and other small river life and ammonia. 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 CM11, which is treated before it reaches homes.
Keep reading
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- 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
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- Best water softener UKHarvey, Kinetico, BWT, Monarch and Water2Buy compared
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- 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 CM11
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 CM11.