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Result Interpretation Centre

Testing is only useful if you know what the result means. This centre helps you understand common UK reference points, what home screening can and cannot tell you, and whether the next step is reassurance, retesting, monitoring, supplier contact, council advice or laboratory confirmation.

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What home screening can and cannot tell you

A home water test can give useful tap-level screening context. It can show whether a result looks low, elevated, present, absent or worth repeating. It cannot prove permanent safety, replace official monitoring, diagnose health symptoms, or provide formal laboratory confirmation for decisions that need documented evidence.

  • Use screening to decide what to do next, not as a final certificate

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  • Sampling point, timing, first-draw/flushed context and private-supply conditions matter

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  • Repeat unexpected results before over-reading one sample, unless urgent action is needed

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  • Use supplier, council or laboratory routes where formal confirmation is needed

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Common result types and reference points

Different results need different interpretation. Lead and arsenic are commonly considered against 10 ug/L reference points. Fluoride is commonly considered against 1.5 mg/L. E. coli should not be present in drinking water. Chlorine needs context because low residual can be normal in mains water, while sudden, strong or persistent taste and smell should be investigated.

  • Lead: 10 ug/L reference point; first-draw versus flushed sampling and pipework matter; boiling does not remove lead​. The WHO advises there is 'no safe level' of Lead in drinking water.

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  • E. coli/bacteria: E. coli should not be present; positive results need careful action, especially on private supplies

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  • Arsenic: 10 ug/L reference point; private supply, groundwater and geology context matter

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  • Fluoride: 1.5 mg/L reference point; separate natural fluoride from fluoridation policy, use our Fluoride Map Overlay to see your local level

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  • Chlorine: low residual can be normal; strong, sudden or persistent issues need supplier or taste/smell route

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Retest, confirm or escalate

The right action depends on the result, source, sampling confidence and consequence of being wrong. Some results are best repeated carefully. Others need supplier contact, council advice or laboratory confirmation. Use SustainWater to screen, understand and act without turning a single result into either panic or false reassurance.

  • Retest when sampling may have been poor, timing was unusual or the result is unexpected

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  • Contact your water company for mains-water incidents, sudden widespread changes or supplier-side concerns

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  • Contact your local council for private supply contamination, tenants, guests or shared supplies

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  • Use laboratory confirmation where decisions affect treatment, property, health advice or formal responsibilities

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  • Use the UK water testing map to fins you water company, local context and community context, not official monitoring.

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