Amersham/Prestwood: supplier water report
This is a report for the named source area. Check your postcode before assuming it describes the water serving your address.
Affinity Water · Supply area: Amersham/Prestwood
Published water hardness
325mg/l as CaCO₃
Very hard
Hardness reporting period: 2025
This value comes from the annual report. Affinity’s live hardness checker can show a different summary; compare the reporting periods before treating it as a change.
1 samples · reported range 325–325 mg/l
This hardness can contribute to limescale in kettles and appliances. Use the units in your appliance manual and follow its care instructions. Hardness is not a health or safety score.
3.25 mmol/l
A conversion of the published hardness, not another test. Follow your appliance’s model-specific instructions.
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.
A comparable historical series is not available yet. We will add earlier reports when we can verify their periods and source areas.
Inside the supplier report
Period: 2025. Summary values do not establish that every sample complied. Read the supplier’s notes for investigations and actions.
Hardness and minerals 7 parameters
Useful for understanding mineral composition and appliance settings. Different minerals are separate measurements; hardness does not determine them all.
Alkalinity334 mgHCO3/l
Source parameter: Alkalinity. Published mean: 334 mgHCO3/l.
Samples: 1. Range: 334 to 334.
Source limit or reference: No PCV.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Calcium130 mgCa/l
Source parameter: Calcium. Published mean: 130 mgCa/l.
Samples: 1. Range: 130 to 130.
Source limit or reference: No PCV.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Fluoride0.105 mgF/l
Source parameter: Fluoride. Published mean: 0.105 mgF/l.
Samples: 8. Range: 0.095 to 0.117.
Source limit or reference: 1.5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Hardness (Total)325 mgCaCO3/l
Source parameter: Hardness (Total). Published mean: 325 mgCaCO3/l.
Samples: 1. Range: 325 to 325.
Source limit or reference: No PCV.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Sodium17 mgNa/l
Source parameter: Sodium. Published mean: 17 mgNa/l.
Samples: 8. Range: 14.2 to 19.4.
Source limit or reference: 200.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Chloride32 mgCl/l
Source parameter: Chloride. Published mean: 32 mgCl/l.
Samples: 8. Range: 30 to 36.
Source limit or reference: 250.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Sulphate20 mgSO4/l
Source parameter: Sulphate. Published mean: 20 mgSO4/l.
Samples: 8. Range: 15 to 23.
Source limit or reference: 250.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Taste, appearance and treatment 6 parameters
These are published sample results. They cannot diagnose a change in taste, smell or appearance at your tap today.
Chlorine (Residual)0.21 mgCl2/l
Source parameter: Chlorine (Residual). Published mean: 0.21 mgCl2/l.
Samples: 143. Range: <0.05 to 0.86.
Source limit or reference: No PCV.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Colour<2 mg/l Pt/Co
Source parameter: Colour. Published mean: <2.0 mg/l Pt/Co.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 52. Range: <1.9 to <2.0.
Source limit or reference: 20.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
pH (acidity / alkalinity)7.1 pH value
Source parameter: Hydrogen Ion (pH). Published mean: 7.1 pH value.
Samples: 52. Range: 6.8 to 7.3.
Source limit or reference: 6.5-9.5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Turbidity<0.1 NTU
Source parameter: Turbidity. Published mean: <0.10 NTU.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 52. Range: <0.10 to 0.24.
Source limit or reference: 4.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Electrical Conductivity at 20 °C579 μS/cm at 20 °C
Source parameter: Electrical Conductivity at 20 °C. Published mean: 579 μS/cm at 20 °C.
Samples: 52. Range: 515 to 624.
Source limit or reference: 2500.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Total Organic Carbon0.6 mgC/l
Source parameter: Total Organic Carbon. Published mean: 0.6 mgC/l.
Samples: 8. Range: 0.5 to 0.7.
Source limit or reference: No abnormal change.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Metals 13 parameters
Keep the units and sampling context when comparing results. Plumbing at an individual property can affect metal measurements.
Arsenic0.4 μgAs/l
Source parameter: Arsenic. Published mean: 0.4 μgAs/l.
Samples: 8. Range: 0.3 to 0.4.
Source limit or reference: 10.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Aluminium<2 μgAl/l
Source parameter: Aluminium. Published mean: <2.0 μgAl/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <2.0 to <2.0.
Source limit or reference: 200.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Antimony0.05 μgSb/l
Source parameter: Antimony. Published mean: 0.05 μgSb/l.
Samples: 8. Range: <0.03 to 0.07.
Source limit or reference: 5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Cadmium<0.05 μgCd/l
Source parameter: Cadmium. Published mean: <0.05 μgCd/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.05 to <0.05.
Source limit or reference: 5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Chromium<0.4 μgCr/l
Source parameter: Chromium. Published mean: <0.4 μgCr/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.2 to <0.4.
Source limit or reference: 50.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Copper0.071 mgCu/l
Source parameter: Copper. Published mean: 0.071 mgCu/l.
Samples: 8. Range: 0.012 to 0.162.
Source limit or reference: 2.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Iron<9 μgFe/l
Source parameter: Iron. Published mean: <9.0 μgFe/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <3.3 to <9.0.
Source limit or reference: 200.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Lead1.28 μgPb/l
Source parameter: Lead. Published mean: 1.28 μgPb/l.
Samples: 8. Range: <0.08 to 9.89.
Source limit or reference: 10.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Manganese<0.4 μgMn/l
Source parameter: Manganese. Published mean: <0.4 μgMn/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.4 to 0.6.
Source limit or reference: 50.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Mercury<0.02 μgHg/l
Source parameter: Mercury. Published mean: <0.02 μgHg/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.02 to <0.02.
Source limit or reference: 1.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Nickel1.3 μgNi/l
Source parameter: Nickel. Published mean: 1.3 μgNi/l.
Samples: 8. Range: 0.9 to 2.1.
Source limit or reference: 20.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Boron<0.046 mgB/l
Source parameter: Boron. Published mean: <0.046 mgB/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.045 to <0.046.
Source limit or reference: 1.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Selenium<0.4 μgSe/l
Source parameter: Selenium. Published mean: <0.4 μgSe/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.4 to 0.5.
Source limit or reference: 10.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Microbiology 4 parameters
Open each result for sample counts and reported contraventions. An unavailable mean is not a zero result. The supplier’s investigation notes provide essential context.
E coli0 No./100ml
Source parameter: E coli. Published mean: 0 No./100ml.
Samples: 143. Range: 0 to 0.
Source limit or reference: 0.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Clostridium perfringens0 No./100ml
Source parameter: Clostridium perfringens. Published mean: 0 No./100ml.
Samples: 8. Range: 0 to 0.
Source limit or reference: 0.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Enterococci0 No./100ml
Source parameter: Enterococci. Published mean: 0 No./100ml.
Samples: 8. Range: 0 to 0.
Source limit or reference: 0.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
3 day plate count 22 °C21 No./1ml at 22 °C
Source parameter: 3 day plate count 22 °C. Published mean: 21 No./1ml at 22 °C.
Samples: 52. Range: 0 to 960.
Source limit or reference: No abnormal change.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Other monitored substances 15 parameters
The source names are retained so you can find the same entry in the original report. A less-than symbol means the reported number is not an exact concentration.
Temperature13.7 °C
Source parameter: Temperature. Published mean: 13.7 °C.
Samples: 144. Range: 6.3 to 22.2.
Source limit or reference: No PCV.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Atrazine<0.011 μg/l
Source parameter: Atrazine. Published mean: <0.011 μg/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.011 to 0.011.
Source limit or reference: 0.1.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Total Pesticide0.024 μg/l
Source parameter: Total Pesticide. Published mean: 0.024 μg/l.
Samples: 7. Range: 0.013 to 0.038.
Source limit or reference: 0.5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Ammonium<0.06 mgNH4/l
Source parameter: Ammonium. Published mean: <0.06 mgNH4/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.05 to <0.06.
Source limit or reference: 0.5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Benzene<0.18 μg/l
Source parameter: Benzene. Published mean: <0.18 μg/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.17 to <0.18.
Source limit or reference: 1.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Benzo (a) Pyrene<0.001 μg/l
Source parameter: Benzo (a) Pyrene. Published mean: <0.001 μg/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 9. Range: <0.001 to <0.001.
Source limit or reference: 0.01.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Bromate<1.5 μgBrO3/l
Source parameter: Bromate. Published mean: <1.5 μgBrO3/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <1.5 to <1.5.
Source limit or reference: 10.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Nitrate21.7 mgNO3/l
Source parameter: Nitrate. Published mean: 21.7 mgNO3/l.
Samples: 8. Range: 19.3 to 24.1.
Source limit or reference: 50.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Nitrite<0.01 mgNO2/l
Source parameter: Nitrite. Published mean: <0.010 mgNO2/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <0.007 to <0.010.
Source limit or reference: 0.5.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Sum of Tri & Tetrachloroethene0 μg/l
Source parameter: Sum of Tri & Tetrachloroethene. Published mean: 0 μg/l.
Samples: 9. Range: 0 to 0.
Source limit or reference: 10.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Tetrachloromethane<0.2 μg/l
Source parameter: Tetrachloromethane. Published mean: <0.2 μg/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 9. Range: <0.2 to <0.2.
Source limit or reference: 3.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Total Cyanide<6.5 μgCN/l
Source parameter: Total Cyanide. Published mean: <6.5 μgCN/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 8. Range: <6.5 to <6.5.
Source limit or reference: 50.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Total PAHs0 μg/l
Source parameter: Total PAHs. Published mean: 0 μg/l.
Samples: 9. Range: 0 to 0.002.
Source limit or reference: 0.1.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Total Trihalomethanes11.21 μg/l
Source parameter: Total Trihalomethanes. Published mean: 11.21 μg/l.
Samples: 9. Range: 5.5 to 17.53.
Source limit or reference: 100.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
1, 2 dichloroethane<0.15 μg/l
Source parameter: 1, 2 dichloroethane. Published mean: <0.15 μg/l.
The symbol is part of the source result; do not treat this as an exact concentration.
Samples: 9. Range: <0.15 to <0.15.
Source limit or reference: 3.
Samples reported as contravening the source requirement: 0. This is historical reporting, not a current incident notification.
Unlisted parameters are not necessarily absent from the water. They may be unavailable in this extraction. The full supplier report remains the primary reference.
Source, dates and help
- Reporting period
- 2025
- Source retrieved
- 2026-02-26
- Last verified source check
- 2026-09-06
- Original source
- Affinity Water report
Published area statistics are not a test at your home or a current incident report.
How we handle the data · Report a correction · Official supplier help and updates
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