Turbidity is a measure of the “cloudiness” of the water which can be caused by tiny air bubbles or finely suspended particles. It can be caused by a disruption to residue in the mains or can be due to poor water quality. There is no defined limit for Turbidity at the customer’s tap under the Drinking Water Regulations however a guideline limit of 4NTU (Nephelometric Turbidity Units) is generally used. The cloudiness of water is typically caused by tiny particles that are suspended in the water. Turbidity is measured in Nephelometric Turbidity Units (NTU) and water below 4NTU will be visibly clear to the human eye. Turbidity is an indicator parameter for drinking water. In drinking regulations it is defined as an Indicator parameter.
What is a Turbidity exceedance?
The limit for Turbidity in drinking water leaving a surface water treatment plant is 1NTU (Nephelometric Turbidity Units). However, for drinking water samples tested at the point of compliance (which is typically the kitchen tap), the limit is aesthetic. A general guideline limit of 4NTU for aesthetic purposes is recommended.
What causes a Turbidity exceedance?
Exceedances for Turbidity can be due to disruption of sediment in cast iron mains or can also indicate that the water treatment process may not be operating effectively.