Mains Cleaning

Pipeline Utilities use a number of different methods to clean water main pipes. These include Flushing, Swabbing and Air Scouring. All of these methods will improve the water quality from the existing pipes by removing any deposits (grit and debris) that have built up over time and can cause water to become discoloured.


Mains cleaning by Swabbing is accomplished by propelling the 'swab' down the pipeline to the exit point with potable water. The swab is generally a foam tube with a diameter the same size as the internal bore of the water main to be cleaned. The water pressure pushes the foam swab through the pipe which in turn pushes the sediment which has built up in the pipe. The swab will exit at a fire hydrant , flushing is continued until the water is completely clear. it is typical to use more than one swab per section of main depending on the level of contamination.

Air Scouring

Mains Cleaning using air scouring is achieved by injecting filtered air into the water main. A water valve is partially closed to allow a small amount of water to pass through the main. An Air scouring unit at the next valve allows air to be injected into the water flow. Inside the water main this creates 'slugs' of water which disturb the sediment in the pipe. Once the sediment has been disturbed, it is moving with the flow of water to a designated washout point. The water is then monitored until there is no more discolouring and until the water has been cleaned to the desired standard. 


A natural sediment very similar to rust builds up in old iron water mains, over time, and normally sits harmlessly in the bottom of pipes. However, if disturbed by increased flow ( possibly due to a burst main) or flow reversal (to maintain supplies) this sediment can cause discolouration of supply . Although not harmful to health, the appearance of the water is impaired and may not be palatable.



At Pipeline Utilities, we work with local water companies to target particular areas that suffer from discolouring of supply. The rust deposits, mostly iron and manganese can be removed by flushing water through the affected pipes at high pressure. Water samples are taken before, during and after the process to prove the main has been cleaned to the desired standard.