Drinking water quality parameters

pH describes how acidic or alkaline water is. It can affect coagulation and how chlorine is present in water, so pH trends are often interpreted alongside chemical dosing and the stage of treatment. A change can be useful context when filtration performance also changes.

A separate pH measurement is needed. Record the sampling point, temperature and time so a pH reading can be compared with the correct turbidity trend.

Electrical conductivity reflects how readily water conducts electricity. It is influenced by the dissolved ions in the water and by temperature. A trend may help operators recognise a source change or an altered blend, but it does not identify which ions are present.

Compare readings on a consistent temperature basis. Record the sample point and operating conditions if conductivity is being used to explain a change in a separate measurement.

Residual chlorine is the chlorine remaining after it has reacted with substances in the water. The required measurement depends on the treatment process and whether the team needs to follow free chlorine, total chlorine or a specific combined residual.

Use a dedicated measurement and interpret it with the dosing, contact and operating records for the site. Low turbidity describes the optical quality of the sample and cannot establish a disinfectant residual.

UV transmittance helps describe the water entering a UV reactor. Water can absorb UV light because of dissolved substances even when it has low turbidity, so the two readings describe different properties.

Use a dedicated UVT measurement where the treatment design requires it. Review the result alongside other reactor conditions and the turbidity trend where that provides useful upstream context.

Explore the pre-UV application

Drinking water colour can arise from dissolved organic matter or metals, and particles can affect its apparent colour. Whether the measurement includes suspended material depends on the method and how the sample was prepared.

Keep the colour method and sample preparation with the result. Colour and turbidity can change together when source conditions change, but they need separate measurements and should stay separate in the plant record.