South End Watermain Flushing

The Municipality of North Cowichan is undertaking routine watermain flushing in various areas of the South End water system between Saturday, April 14, and Friday, May 25, inclusive. Users may experience some chlorine odour and flavour. There may be short periods of low pressure and discolouration of water.

Why are we flushing?

Flushing is necessary to maintain water quality. The water entering distribution mains is of very high quality; however, water quality can deteriorate in distribution mains if the mains are not properly managed.

Flushing maintains water quality in several ways, including:

  1. Removes sediment from the mains.  Sediment mostly includes iron and manganese. Iron sediment results from corrosion of iron pipes and valves used in the distribution system. Other iron sediment result from the change of dissolved iron which occurs naturally in our water into sediment form. This occurs in the presence of chlorine and oxygen under certain low ?ow conditions. Dissolved manganese also occurs naturally in our water and it can be changed into sediment, as with iron.

    Although iron and manganese do not pose health concerns, they can degrade the acceptability of the water through affecting the taste, clarity, and colour of the water. In addition, sediment can shield micro-organisms from the disinfecting power of chlorine; therefore, such sediment could contribute to the growth of micro-organisms within distribution mains.

  2. Flushing helps remove stale water. Much of our distribution system is designed with loops or interconnected grids, which keep water constantly moving around. However, some areas have dead ends where water moves slowly and sits for longer periods of time. Such dead-end mains need to be ?ushed to ensure the presence of fresh water with suf?cient dissolved oxygen, disinfectant levels and an acceptable taste and smell.