We have two main programmes of work: water main rehabilitation and operational maintenance.
We replace and reline water mains in areas where we have identified a pattern of customers experiencing discoloured water.
We also regularly clean water mains to remove settled deposits which can build up over time and cause discoloured water. Very low concentrations of naturally occurring metals such as iron and manganese may still be present in the water after it is has been treated and over extended periods of time can collect on the inside of pipes. If these deposits are disturbed due to a sudden change in flow (caused by a burst main, for example) it could make the water appear discoloured.
To prevent discoloration of supplies we remove any build-up in a controlled and planned way. We do this by generating a higher flow within the pipe by discharging water from hydrants at precise rates and locations. This rarely affects the quality of water that reaches your home as we carefully plan and design this process.
To clean larger pipes we may apply more innovative and intrusive techniques to clear any settled deposits. Most innovative is the use of ice slurry that is injected into the pipe. The ice picks up the deposits and carries it away to a designed exit point from the pipe. There are other available options which may interrupt water supplies and when we do this we’ll inform you first.