Fresh water system damage
The fresh water supply system was extensively damaged in these ways:
- The earthquakes cracked pipe walls, reducing delivery pressure and spraying water into the surrounding ground area. This wasted water and sometimes destabilised the ground and/or utility conduits.
- Some fresh water pipe sections completely broke, particularly older pipes. Because of the potential to destabilise the ground, these pipes need to be switched off urgently before they are rebuilt.
- Joint breakage
- Where some pipes have been joined together, the shaking has separated the two parts again, so the pipe is essentially broken.
- Thankfully there was very little contamination from wastewater, storm water, or ground water because the water supply pipes are pressurised. However, there was some minor contamination and the risk remains in large future events. After damaging earthquakes, Christchurch City Council asks residents to boil tap water before use as a precaution until they have checked for contamination.
- Reservoir damage
- Some reservoirs were structurally affected but remain usable. In the long term, they will need to be restored. Huntsbury reservoir, our city's biggest, has been seriously damaged, which places significant pressure on the water supply.
- Pump station damage
- Pump station buildings suffered similar non-critical damage as many reservoirs. Most are operating but will need to be fixed properly in the future. One station needs a complete rebuild at a new site.
- Well damage
- Well casings were distorted deep under the surface in September 2010 by the horizontal movement at interfaces between the layers of earth (strata). That effect is known as lateral shear. In February and June 2011 – where the movement profile was much more vertical – well casings lifted, which brought many of the wells out of alignment with the water pipes.