Turbidity Made Clear
Turbidity is a fundamental water safety test, as high turbidity levels can be a signal for a number of quality issues. In this article, we look at what turbidity is, what it is caused by, and how it can be measured.
What is Turbidity?
Water usually contains suspended solids, consisting of particles of varying sizes and properties, which are usually invisible to the naked eye. Many of these particles settle on standing. It is the particles which do not settle, termed colloidal solids, which cause the water to look turbid.
Turbidity refers to the cloudiness or haziness of the water sample caused by the presence of suspended particles, such as sediment, silt, or organic matter.
What Causes Turbidity?
Turbidity of water is caused by the presence of clay, soils, organic matter, and micro-organisms, often from the run-off from industry, agriculture, and domestic sources.
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Measuring Turbidity
The measurement of turbidity is a key test of water quality, as higher turbidity levels can be an indicator for a number of issues. Turbidity is an optical measurement of the water and therefore does not identify individual substances. However, a correlation can be formulated between turbidity and TSS (Total Suspended Solids), this needs to be handled with care as the correlation varies between sites and processes.
There are several ways of expressing turbidity values but one of the most common is the nephelometric turbidity unit (NTU). The human eye can determine turbidity values as low as 4NTU. However, most UK water companies aim to reach a target of less than 1NTU at the drinking water treatment works, and no more than 4NTU from customer taps. Although turbidity in potable water can be due to harmless parameters such as excessive aeration and high calcium levels, higher turbidity values can represent a health risk.
To ensure that water is fit for purpose, the WHO (World Health Organisation) has recommended that turbidity should be measured before and after each unit process at domestic and industrial water treatment facilities. This is because solids can compromise the efficiency of processes such as chlorination and UV disinfection. Chlorine used to ‘clean’ the water can be depleted by oxidising the solid material, reducing its effectiveness to eradicate the harmful micro-organisms. In addition, cloudiness in water will prevent adequate penetration of UV light, thereby affecting disinfection rates through UV treatment.
Palintest has a range of reliable, quick, and simple methods that are designed to be portable and rugged to be used in field for measuring turbidity including the Turbidimeter Plus which you can get as part as a Turbidity Test Kit. If you would like any further information about turbidity or how to effectively measure it, please contact our team or visit our turbidity parameter page.
