Severn Trent Water embarks on a large scale turbidity trial with the Nephnet

Severn Trent Water has embarked on a large scale, forward-thinking trial to monitor for discolouration in a large trunk main, to further protect the overall quality of its drinking water.

The trial is the first of its kind for STW and involves a trunk main from two large cities in the midlands, which is being pushed to increase capacity to double. During the trial, STW will slowly increase the flow rate via a large trunk main, aiming to eventually double the flow over a period of time. However, this could consequently cause issues with discolouration from branches off the mains. The trunk main was designed to allow much greater flows than at present, but has remained minimal due to the previous demand. Now that the demand is increasing, STW is looking to utilise the main as it was designed.

The water company recognised that the only way they could safely double the flowrate of the trunk main was by installing 12 of ATi’s groundbreaking NephNets. The NephNet is the only battery powered, portable turbidity monitor available that gives the same measurement performance as the more traditional fixed monitor, with no compromise on measurement. 

The NephNet is perfect for closely monitoring risks of discolouration due to changes in flow and pressure releasing biofilm from inside the pipework. This can also cause problems to branched supplies if pushed too far too quickly and will alarm at levels of 1 NTU and 4 NTU (changeable).

The portable, battery powered monitor was created to assist the UK water industry with measuring continuous low level turbidity; to help to control the movement of water; provide a better understanding of the networks; improve the quality of data; and prove the effectiveness of flushing DMA in the network. The innovation behind this technology is to maintain the accuracy of the turbidity sensor, whilst reducing the demand for power.

ATi’s UK Sales Manager, Tristen Preger, has worked closely with Severn Trent Water and its contractor Atkins over the past few years to ensure the smooth installation. Tristen said: “The benefits of continuous, accurate data have opened the eyes of many water companies, who have previously struggled to understand the overall condition of their networks. In many cases, network engineers simply do not know the quality of their network. As only spot checks were available, there was a lack of information on why water quality differs so much within an area.

“However, Severn Trent Water has recognised changes in water quality can now be identified and tracked via the NephNet, which is crucial for this trial. If turbidity is detected, the supply can be diverted where possible, and warnings can be sent out to customers to prevent complaints filtering through. 

“The installation was simple - the challenge was making sure there was sufficient phone signal, as this would allow for text and email alarms to be generated. ATi prides itself as 'going the extra mile' to offer our customers a service we would expect. We even went as far as myself and Dr Stewart Husband from Sheffield University personally couriering the 12 NephNets to STW ourselves and overseeing the installation.

“This trial has proved that Severn Trent Water is committed to understanding its networks, and therefore providing customers with improved drinking water and service. With 95% of water companies now using the NephNet, it is continuing to take the industry by storm.”