WESTERHAM: your water explained
Published results for this named supply area. Your address may be served by a different area.
Confirm your address · Check a postcode
Check your full postcode before assuming this area report describes the water serving your address.
Your water at a glance
Hard water. Expect limescale.
For your home, the main practical issue is mineral scale in kettles, showers and appliances. Check your dishwasher setting and follow appliance care instructions.
298 mg/l as CaCO₃
Soft ≤100 · Slightly hard ≤150 · Moderately hard ≤200 · Hard ≤300 · Very hard >300 mg/l. DWI hardness bands; not safety grades.
Published quality checks
59 parameters: no exceedances reported
These labels describe 2025. 10 other parameters have no complete compliance judgement here. They are not a guarantee about an individual tap today.
Understand the reported results ↓Make this useful for your home
Hardness reporting period: 2025 · Quality reporting period: 2025
Appliance settings · Convert hardness units
2.98 mmol/l
A conversion of the published hardness, not another test. Follow your appliance’s model-specific instructions.
A newer source document is awaiting validation. The figures here remain from the approved period shown. Original supplier report ↗
Drinking-water results
What do the important results mean?
Read the status, sample range and source requirement together. A low average can hide an individual exceedance. Green labels mean the supplier reported no exceedances for that parameter and period; amber calls for source context.
E. coli
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 no./100ml
A microbiological indicator. The reported sample results and any failures matter more than an average bacterial count.
36 samples · Range: 0 to 0 no./100ml
No compliance judgement is made from an estimated or unavailable measurement.
Lead
✓ No exceedances reported
Published mean
1.0 µg/l
Source reference: 10 µg/l
Plumbing can affect lead at an individual tap. An area average cannot rule out a problem with pipes at your property.
8 samples · Range: <0.9 to 1.6 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Nitrate
✓ No exceedances reported
Published mean
27.8 mg/l
Source reference: 50 mg/l
A dissolved compound monitored against drinking-water requirements. Its mean, highest reported result and sample count answer different questions.
8 samples · Range: 24.2 to 31.6 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Fluoride
✓ No exceedances reported
Published mean
0.11 mg/l
Source reference: 1.50 mg/l
Can occur naturally or be added through a fluoridation scheme. The concentration alone does not tell you whether it was added; a lower number is not automatically better.
8 samples · Range: 0.08 to 0.14 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
For your household
What should you do next?
Check appliance settings
Match the hardness unit to your dishwasher manual. Settings depend on the model.
Dishwasher guideManage limescale
Follow the manufacturer’s descaling advice. Check what a filter actually removes before buying.
Filters and limescaleA new change at your tap?
For a new taste, smell, colour or supply problem, check current supplier advice. Annual data is not a live incident feed.
Official supplier help ↗Taste, appearance and mineral content
Chlorine, pH and minerals answer different questions. Calcium and magnesium help describe hardness; chloride is different from treatment chlorine. None is a stand-alone water-quality score.
Chlorine residual
Disinfectant remaining after treatment. It can influence taste and smell; a lower concentration is not automatically better.
See the measurement and context ↓pH
Describes acidity and alkalinity on a scale, rather than an amount of a substance. Where the source gives a range, both its lower and upper bounds matter.
See the measurement and context ↓Has the hardness changed?
History for this reported source area. Only comparable annual statistics appear in the chart; rolling summaries are kept separate. These are not daily tests at your address.
2024
294 mg/l as CaCO₃
2025
298 mg/l as CaCO₃
Change between these editions
+4 mg/l as CaCO₃
Scroll the chart sideways on smaller screens, or read the values below. Vertical axis: hardness in mg/l as CaCO₃. Bars show annual means.
Historical figures come from retained source copies. Supplier links may now open a newer edition. Ranges describe the samples reported, not confidence intervals. A short annual series supports a comparison; it does not establish a sustained trend or a change at your tap.
Explore all measurements · 71 parameters · 2025
Every result retains its original units, range, sample count and source notes. Comparisons use the reference printed in this report; qualitative references and missing limits are not converted into invented pass/fail judgements. Unlisted substances are not necessarily absent from the water.
Parameters without their own explanation: A substance monitored in this supplier report. The source reference, units, sample range and any reported failures provide its context; the number alone is not a water-quality rating.
A failure count (under “Original wording and source notes”) supports a pass/fail label only where the report gives an applicable limit for that parameter.
Hardness and minerals 7 parameters
Chloride
✓ No exceedances reported
Published mean
42 mg/l
Source reference: 250 mg/l
A dissolved salt component that can influence taste at higher concentrations. It is different from chlorine used in treatment.
8 samples · Range: 38 to 49 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 250. Source parameter: Chloride as Cl. Original mean: 42 mg/l.
Source failure-count field: 0.
Fluoride
✓ No exceedances reported
Published mean
0.11 mg/l
Source reference: 1.50 mg/l
Can occur naturally or be added through a fluoridation scheme. The concentration alone does not tell you whether it was added; a lower number is not automatically better.
8 samples · Range: 0.08 to 0.14 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 1.50. Source parameter: Fluoride as F. Original mean: 0.11 mg/l.
Source failure-count field: 0.
Sulphate
✓ No exceedances reported
Published mean
38 mg/l
Source reference: 250 mg/l
A dissolved mineral component monitored in water-quality reports. Read its concentration alongside the source reference.
8 samples · Range: 27 to 46 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 250. Source parameter: Sulphate as SO4. Original mean: 38 mg/l.
Source failure-count field: 0.
Total hardness
No numerical limit supplied
Published mean
298 mg/l as CaCO₃
Source reference: Not supplied
Dissolved calcium and magnesium affect limescale and appliance settings. This is a mineral description, not a safety score.
4 samples · Range: 288 to 311 mg/l as CaCO₃
This report gives no numerical limit for this parameter. A higher or lower number is not automatically better.
Original wording and source notes
Source reference: Not supplied. Source parameter: Hardness (Total) as CaCO3. Original mean: 298 mg/l as CaCO₃.
Source failure-count field: 0.
Alkalinity
No numerical limit supplied
Published mean
237 mg/l
Source reference: Not supplied
How strongly water resists a change in acidity. This helps describe its chemistry; it is different from pH and total hardness.
4 samples · Range: 226 to 244 mg/l
This report gives no numerical limit for this parameter. A higher or lower number is not automatically better.
Original wording and source notes
Source reference: Not supplied. Source parameter: Alkalinity as CaCO3. Original mean: 237 mg/l.
Source failure-count field: 0.
Magnesium
No numerical limit supplied
Published mean
3.8 mg/l
Source reference: Not supplied
A naturally occurring mineral that contributes to hardness alongside calcium.
4 samples · Range: 2.4 to 4.3 mg/l
This report gives no numerical limit for this parameter. A higher or lower number is not automatically better.
Original wording and source notes
Source reference: Not supplied. Source parameter: Magnesium. Original mean: 3.8 mg/l.
Source failure-count field: 0.
Sodium
✓ No exceedances reported
Published mean
22 mg/l
Source reference: 200 mg/l
A dissolved salt component. Compare the water measurement with its source reference; it is not a measure of your total dietary salt intake.
8 samples · Range: 13 to 26 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 200. Source parameter: Sodium as Na. Original mean: 22 mg/l.
Source failure-count field: 0.
Taste, appearance and treatment 8 parameters
Colour
✓ No exceedances reported
Published mean
<1.8 mg/l
Source reference: 20 mg/l
A measure of water colour under test conditions. A new change at your tap should be checked with your supplier.
24 samples · Range: <1.8 to <1.8 mg/l
The source reports 0 failures across 24 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 20. Source parameter: Colour (Pt/Co scale). Original mean: <1.8 mg/l.
Source failure-count field: 0.
Conductivity
✓ No exceedances reported
Published mean
609 µS/cm
Source reference: 2500 µS/cm
Indicates how readily water conducts electricity, influenced by dissolved ions. It is not a direct measurement of hardness or safety.
24 samples · Range: 463 to 657 µS/cm
The source reports 0 failures across 24 samples. This describes the published period.
Original wording and source notes
Source reference: 2500. Source parameter: Conductivity at 20°C. Original mean: 609 µS/cm.
Source failure-count field: 0.
pH
✓ No exceedances reported
Published mean
7.29 pH
Source reference: 6.50-9.50 pH
Describes acidity and alkalinity on a scale, rather than an amount of a substance. Where the source gives a range, both its lower and upper bounds matter.
24 samples · Range: 7.10 to 7.50 pH
The source reports 0 failures across 24 samples. This describes the published period.
Original wording and source notes
Source reference: 6.50-9.50. Source parameter: Hydrogen Ion. Original mean: 7.29 pH.
Source failure-count field: 0.
Turbidity
✓ No exceedances reported
Published mean
0.09 FTU
Source reference: 4.00 FTU
Measures cloudiness caused by suspended particles. It cannot identify their cause on its own.
24 samples · Range: <0.09 to 0.17 FTU
The source reports 0 failures across 24 samples. This describes the published period.
Original wording and source notes
Source reference: 4.00. Source parameter: Turbidity. Original mean: 0.09 FTU.
Source failure-count field: 0.
Odour
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 dilution no.
A sensory assessment of smell in the sampled water. It cannot identify the cause of a current change at your tap.
23 samples · Range: 0 to 0 dilution no.
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: 0. Source parameter: Odour (quantatative). Original mean: n/a dilution no..
Source failure-count field: 0.
Taste
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 dilution no.
A sensory assessment of the sampled water. It cannot explain a new taste at your home today.
23 samples · Range: 0 to 0 dilution no.
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: 0. Source parameter: Taste (quantatative). Original mean: n/a dilution no..
Source failure-count field: 0.
Chlorine residual
No numerical limit supplied
Published mean
0.36 mg/l
Source reference: Not supplied
Disinfectant remaining after treatment. It can influence taste and smell; a lower concentration is not automatically better.
36 samples · Range: 0.10 to 0.90 mg/l
This report gives no numerical limit for this parameter. A higher or lower number is not automatically better.
Original wording and source notes
Source reference: Not supplied. Source parameter: Chlorine (Residual). Original mean: 0.36 mg/l.
Source failure-count field: 0.
Total organic carbon
No numerical limit supplied
Published mean
0.7 mg/l
Source reference: Not supplied
A broad measure of organic carbon used to understand water and treatment. It does not identify an individual contaminant.
4 samples · Range: 0.6 to 0.8 mg/l
This report gives no numerical limit for this parameter. A higher or lower number is not automatically better.
Original wording and source notes
Source reference: Not supplied. Source parameter: Total Organic Carbon as C. Original mean: 0.7 mg/l.
Source failure-count field: 0.
Metals 13 parameters
Aluminium
✓ No exceedances reported
Published mean
<8.2 µg/l
Source reference: 200 µg/l
Monitored as part of water-quality testing and treatment control. Compare with the reference and sample results in the source.
8 samples · Range: <8.2 to <8.2 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 200. Source parameter: Aluminium as Al. Original mean: <8.2 µg/l.
Source failure-count field: 0.
Antimony
✓ No exceedances reported
Published mean
<0.3 µg/l
Source reference: 5.0 µg/l
A trace element monitored in drinking water. The source reference and sample results provide the relevant comparison.
8 samples · Range: <0.3 to <0.3 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 5.0. Source parameter: Antimony as Sb. Original mean: <0.3 µg/l.
Source failure-count field: 0.
Arsenic
✓ No exceedances reported
Published mean
<0.7 µg/l
Source reference: 10.0 µg/l
A trace element monitored against a drinking-water requirement. Use the source results and units rather than taste or appearance to interpret it.
8 samples · Range: <0.7 to <0.7 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 10.0. Source parameter: Arsenic as As. Original mean: <0.7 µg/l.
Source failure-count field: 0.
Boron
✓ No exceedances reported
Published mean
0.04 mg/l
Source reference: 1.00 mg/l
A dissolved element monitored in drinking water. The source reference applies to the parameter and units shown here.
8 samples · Range: 0.03 to 0.05 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 1.00. Source parameter: Boron as B. Original mean: 0.04 mg/l.
Source failure-count field: 0.
Cadmium
✓ No exceedances reported
Published mean
<0.4 µg/l
Source reference: 5.0 µg/l
A trace metal monitored in drinking water. A less-than result reports an upper bound, not a measured zero.
8 samples · Range: <0.4 to <0.4 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 5.0. Source parameter: Cadmium as Cd. Original mean: <0.4 µg/l.
Source failure-count field: 0.
Chromium
✓ No exceedances reported
Published mean
<2.5 µg/l
Source reference: 50 µg/l
A trace metal monitored in drinking-water reports. Keep the source’s chemical definition and units when comparing results.
8 samples · Range: <2.5 to <2.5 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 50. Source parameter: Chromium as Cr. Original mean: <2.5 µg/l.
Source failure-count field: 0.
Copper
✓ No exceedances reported
Published mean
0.07 mg/l
Source reference: 2.00 mg/l
Can be influenced by plumbing. The area report does not replace investigation of a problem at an individual property.
8 samples · Range: <0.01 to 0.40 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 2.00. Source parameter: Copper as Cu. Original mean: 0.07 mg/l.
Source failure-count field: 0.
Iron
✓ No exceedances reported
Published mean
10 µg/l
Source reference: 200 µg/l
Can affect water colour, staining and taste. A historical result does not diagnose a change in your tap water today.
8 samples · Range: <7 to 28 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 200. Source parameter: Iron as Fe. Original mean: 10 µg/l.
Source failure-count field: 0.
Lead
✓ No exceedances reported
Published mean
1.0 µg/l
Source reference: 10 µg/l
Plumbing can affect lead at an individual tap. An area average cannot rule out a problem with pipes at your property.
8 samples · Range: <0.9 to 1.6 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 10. Source parameter: Lead as Pb. Original mean: 1.0 µg/l.
Source failure-count field: 0.
Manganese
✓ No exceedances reported
Published mean
0.7 µg/l
Source reference: 50 µg/l
Can affect colour and deposits. Any reported exceedance needs the supplier’s investigation context.
8 samples · Range: <0.6 to 1.8 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 50. Source parameter: Manganese as Mn. Original mean: 0.7 µg/l.
Source failure-count field: 0.
Mercury
✓ No exceedances reported
Published mean
<0.07 µg/l
Source reference: 1.00 µg/l
A trace metal monitored against drinking-water requirements. Keep detection limits separate from exact measurements.
4 samples · Range: <0.07 to <0.07 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 1.00. Source parameter: Mercury as Hg. Original mean: <0.07 µg/l.
Source failure-count field: 0.
Nickel
✓ No exceedances reported
Published mean
1.4 µg/l
Source reference: 20 µg/l
A monitored metal that can be influenced by materials in contact with water. Local plumbing and sampling context matter.
8 samples · Range: <0.7 to 5.0 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 20. Source parameter: Nickel as Ni. Original mean: 1.4 µg/l.
Source failure-count field: 0.
Selenium
✓ No exceedances reported
Published mean
0.9 µg/l
Source reference: 10 µg/l
A trace element monitored in drinking water. Its presence alone does not establish that a requirement was exceeded.
8 samples · Range: 0.5 to 1.3 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 10. Source parameter: Selenium as Se. Original mean: 0.9 µg/l.
Source failure-count field: 0.
Microbiology 5 parameters
Clostridium perfringens
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 no./100ml
A microbiological indicator used in water-quality monitoring. Check the sample results and source investigation context.
4 samples · Range: 0 to 0 no./100ml
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: 0. Source parameter: Clostridium perfringens. Original mean: n/a no./100ml.
Source failure-count field: 0.
Coliform bacteria
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 no./100ml
Used to monitor water-system hygiene. Interpret detections with the supplier’s sampling location and investigation notes.
36 samples · Range: 0 to 0 no./100ml
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: 0. Source parameter: Coliform bacteria. Original mean: n/a no./100ml.
Source failure-count field: 0.
Colony count at 22°C
Measured result unavailable
Published mean
Mean not reported
Source reference: Not supplied
A general bacterial count used to monitor changes in the supply. It is not equivalent to an E. coli result.
24 samples · Range: 0 to 0 no./ml
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: Not supplied. Source parameter: Colony count 22°C. Original mean: n/a no./ml.
Source failure-count field: 0.
E. coli
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 no./100ml
A microbiological indicator. The reported sample results and any failures matter more than an average bacterial count.
36 samples · Range: 0 to 0 no./100ml
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: 0. Source parameter: E. coli. Original mean: n/a no./100ml.
Source failure-count field: 0.
Enterococci
Measured result unavailable
Published mean
Mean not reported
Source reference: 0 no./100ml
A microbiological indicator assessed through sample results. Read any reported failures with the supplier’s investigation notes.
8 samples · Range: 0 to 0 no./100ml
No compliance judgement is made from an estimated or unavailable measurement.
Original wording and source notes
Source reference: 0. Source parameter: Enterococci. Original mean: n/a no./100ml.
Source failure-count field: 0.
Other monitored substances 38 parameters
Ammonium as NH4
✓ No exceedances reported
Published mean
<0.03 mg/l
Source reference: 0.50 mg/l
About this parameter: see the note above this list.
8 samples · Range: <0.03 to <0.03 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.50. Source parameter: Ammonium as NH4. Original mean: <0.03 mg/l.
Source failure-count field: 0.
Cyanide as CN
✓ No exceedances reported
Published mean
<1.4 µg/l
Source reference: 50 µg/l
About this parameter: see the note above this list.
4 samples · Range: <1.4 to <1.4 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 50. Source parameter: Cyanide as CN. Original mean: <1.4 µg/l.
Source failure-count field: 0.
Nitrate
✓ No exceedances reported
Published mean
27.8 mg/l
Source reference: 50 mg/l
A dissolved compound monitored against drinking-water requirements. Its mean, highest reported result and sample count answer different questions.
8 samples · Range: 24.2 to 31.6 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 50. Source parameter: Nitrate as NO3. Original mean: 27.8 mg/l.
Source failure-count field: 0.
Nitrate/Nitrite calculation
✓ No exceedances reported
Published mean
0.56 mg/l
Source reference: 1.00 mg/l
About this parameter: see the note above this list.
8 samples · Range: 0.48 to 0.63 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 1.00. Source parameter: Nitrate/Nitrite calculation. Original mean: 0.56 mg/l.
Source failure-count field: 0.
Nitrite
✓ No exceedances reported
Published mean
<0.02 mg/l
Source reference: 0.50 mg/l
A nitrogen compound monitored in water supplies. Requirements can depend on where the sample was collected; use the reference printed in this report.
8 samples · Range: <0.02 to <0.02 mg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.50. Source parameter: Nitrite as NO2. Original mean: <0.02 mg/l.
Source failure-count field: 0.
Benzo (a) pyrene
✓ No exceedances reported
Published mean
<0.001 µg/l
Source reference: 0.010 µg/l
About this parameter: see the note above this list.
9 samples · Range: <0.001 to <0.001 µg/l
The source reports 0 failures across 9 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.010. Source parameter: Benzo (a) pyrene. Original mean: <0.001 µg/l.
Source failure-count field: 0.
PAHs (Sum of 4 substances)
✓ No exceedances reported
Published mean
0.000 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
8 samples · Range: 0.000 to 0.001 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 0.100. Source parameter: PAHs (Sum of 4 substances). Original mean: 0.000 µg/l.
Source failure-count field: 0.
1,2 dichloroethane
✓ No exceedances reported
Published mean
<0.1 µg/l
Source reference: 3.0 µg/l
About this parameter: see the note above this list.
8 samples · Range: <0.1 to <0.1 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 3.0. Source parameter: 1,2 dichloroethane. Original mean: <0.1 µg/l.
Source failure-count field: 0.
Benzene
✓ No exceedances reported
Published mean
<0.1 µg/l
Source reference: 1.0 µg/l
About this parameter: see the note above this list.
8 samples · Range: <0.1 to <0.1 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 1.0. Source parameter: Benzene. Original mean: <0.1 µg/l.
Source failure-count field: 0.
Tetra- & Trichloroethene calc
✓ No exceedances reported
Published mean
0.5 µg/l
Source reference: 10 µg/l
About this parameter: see the note above this list.
8 samples · Range: 0.0 to 1.0 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 10. Source parameter: Tetra- & Trichloroethene calc. Original mean: 0.5 µg/l.
Source failure-count field: 0.
Tetrachloromethane
✓ No exceedances reported
Published mean
<0.1 µg/l
Source reference: 3.0 µg/l
About this parameter: see the note above this list.
8 samples · Range: <0.1 to <0.1 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 3.0. Source parameter: Tetrachloromethane. Original mean: <0.1 µg/l.
Source failure-count field: 0.
Trihalomethanes
✓ No exceedances reported
Published mean
13 µg/l
Source reference: 100 µg/l
About this parameter: see the note above this list.
8 samples · Range: 7 to 22 µg/l
The source reports 0 failures across 8 samples. This describes the published period.
Original wording and source notes
Source reference: 100. Source parameter: Trihalomethanes. Original mean: 13 µg/l.
Source failure-count field: 0.
Bromate as BrO3
✓ No exceedances reported
Published mean
<1.0 µg/l
Source reference: 10.0 µg/l
About this parameter: see the note above this list.
4 samples · Range: <1.0 to <1.0 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 10.0. Source parameter: Bromate as BrO3. Original mean: <1.0 µg/l.
Source failure-count field: 0.
2,4-D
✓ No exceedances reported
Published mean
<0.017 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.017 to <0.017 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: 2,4-D. Original mean: <0.017 µg/l.
Source failure-count field: 0.
2,4-DB
✓ No exceedances reported
Published mean
<0.018 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.018 to <0.018 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: 2,4-DB. Original mean: <0.018 µg/l.
Source failure-count field: 0.
Atrazine
✓ No exceedances reported
Published mean
<0.005 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.005 to <0.005 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Atrazine. Original mean: <0.005 µg/l.
Source failure-count field: 0.
Bentazone
✓ No exceedances reported
Published mean
<0.012 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.012 to <0.012 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Bentazone. Original mean: <0.012 µg/l.
Source failure-count field: 0.
Bromoxynil
✓ No exceedances reported
Published mean
<0.019 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.019 to <0.019 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Bromoxynil. Original mean: <0.019 µg/l.
Source failure-count field: 0.
Carbendazim
✓ No exceedances reported
Published mean
<0.009 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.009 to <0.009 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Carbendazim. Original mean: <0.009 µg/l.
Source failure-count field: 0.
Carbetamide
✓ No exceedances reported
Published mean
<0.007 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.007 to <0.007 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Carbetamide. Original mean: <0.007 µg/l.
Source failure-count field: 0.
Chlortoluron
✓ No exceedances reported
Published mean
<0.006 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.006 to <0.006 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Chlortoluron. Original mean: <0.006 µg/l.
Source failure-count field: 0.
Clopyralid
✓ No exceedances reported
Published mean
<0.023 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.023 to <0.023 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Clopyralid. Original mean: <0.023 µg/l.
Source failure-count field: 0.
Dicamba
✓ No exceedances reported
Published mean
<0.022 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.022 to <0.022 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Dicamba. Original mean: <0.022 µg/l.
Source failure-count field: 0.
Dichlorprop
✓ No exceedances reported
Published mean
<0.012 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.012 to <0.012 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Dichlorprop. Original mean: <0.012 µg/l.
Source failure-count field: 0.
Diuron
✓ No exceedances reported
Published mean
<0.006 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.006 to <0.006 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Diuron. Original mean: <0.006 µg/l.
Source failure-count field: 0.
Fluroxypyr
✓ No exceedances reported
Published mean
<0.019 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.019 to <0.019 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Fluroxypyr. Original mean: <0.019 µg/l.
Source failure-count field: 0.
Isoproturon
✓ No exceedances reported
Published mean
<0.005 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.005 to <0.005 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Isoproturon. Original mean: <0.005 µg/l.
Source failure-count field: 0.
Linuron
✓ No exceedances reported
Published mean
<0.005 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.005 to <0.005 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Linuron. Original mean: <0.005 µg/l.
Source failure-count field: 0.
MCPA
✓ No exceedances reported
Published mean
<0.02 µg/l
Source reference: 0.10 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.02 to <0.02 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.10. Source parameter: MCPA. Original mean: <0.02 µg/l.
Source failure-count field: 0.
Mecoprop
✓ No exceedances reported
Published mean
<0.014 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.014 to <0.014 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Mecoprop. Original mean: <0.014 µg/l.
Source failure-count field: 0.
Metaldehyde
✓ No exceedances reported
Published mean
<0.009 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.009 to <0.009 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Metaldehyde. Original mean: <0.009 µg/l.
Source failure-count field: 0.
Monuron
✓ No exceedances reported
Published mean
<0.005 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.005 to <0.005 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Monuron. Original mean: <0.005 µg/l.
Source failure-count field: 0.
Pentachlorophenol
✓ No exceedances reported
Published mean
<0.019 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.019 to <0.019 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Pentachlorophenol. Original mean: <0.019 µg/l.
Source failure-count field: 0.
Picloram
✓ No exceedances reported
Published mean
<0.021 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.021 to <0.021 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Picloram. Original mean: <0.021 µg/l.
Source failure-count field: 0.
Propyzamide
✓ No exceedances reported
Published mean
<0.006 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.006 to <0.006 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Propyzamide. Original mean: <0.006 µg/l.
Source failure-count field: 0.
Simazine
✓ No exceedances reported
Published mean
<0.009 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.009 to <0.009 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Simazine. Original mean: <0.009 µg/l.
Source failure-count field: 0.
Triclopyr
✓ No exceedances reported
Published mean
<0.016 µg/l
Source reference: 0.100 µg/l
About this parameter: see the note above this list.
4 samples · Range: <0.016 to <0.016 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
“<” is part of the source result. It is not an exact concentration or a measured zero.
Original wording and source notes
Source reference: 0.100. Source parameter: Triclopyr. Original mean: <0.016 µg/l.
Source failure-count field: 0.
Total Pesticides
✓ No exceedances reported
Published mean
0.000 µg/l
Source reference: 0.500 µg/l
About this parameter: see the note above this list.
4 samples · Range: 0.000 to 0.000 µg/l
The source reports 0 failures across 4 samples. This describes the published period.
Original wording and source notes
Source reference: 0.500. Source parameter: Total Pesticides. Original mean: 0.000 µg/l.
Source failure-count field: 0.
Sources, dates and how to interpret this page
- Reporting period
- 2025
- Source retrieved
- 2026-09-06
- Last verified source check
- 2026-09-20
- Original publication
- Thames Water report ↗
Published supply-zone statistics are not a test at your home or a current incident notification.
Compliance counts describe the reporting period. Read the supplier’s annual review for investigation findings and property-specific context.
Hardness: 4 samples · reported range 288 to 311 mg/l as CaCO₃.
Status labels describe the published parameter and period. Historical exceedances do not automatically establish a current incident. Numerical limits are taken from the original report, not applied indiscriminately across countries, dates or sampling locations. DWI explains how standards work in England and Wales.
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