Rebuilding the fresh water network
Different kinds of damage requires a range of fixes, although our goal is to restore the capacity of the water supply to pre-earthquake capacity (“like for like”), we are also building more facilities and bringing old designs up to date where it is justifiable.
Our work on fresh water pipes might mean we have to turn off supplies temporarily. We always try to give you as much warning as possible about this. There may also be temporary “boil your water” warnings after serious aftershocks as a precaution against contamination. For you and your family's health, you should heed all warnings about drinking tap water.
Keep an emergency supply of fresh drinking water at home for temporary outages and heed warnings about drinking tap water.
There is a three year program underway to rebuild damaged wells and drill new ones to replace ones that can't be repaired.
We fix water supply infrastructure permanently wherever that's the best choice, but it's important to realise that some rebuilding is temporary for good reasons.
Techniques we use
- Better materials
- When presented with the opportunity, we replace infrastructure with a stronger alternative. In the case of pipes, we replace older materials with longer lasting and more robust polyethylene or PVC piping.
- Hand digging and hydro-excavation
- Sometimes we need to be extremely careful to avoid disruptions to other services using the same trench, and to avoid dangers like electrocution. In these cases, we can't use traditional excavating machinery, and have to hand dig or use hydro-excavators.
- Flexible joints for wells
- Because many well casings came out of alignment with discharge pipes in the vertical shaking of 2011, we've retro-fitted more flexible joints to replace the broken ones which allow more movement.
- Stronger wells
- Well heads and well chambers have been innovatively redesigned to allow for much greater levels of displacement in case of future earthquakes.
- Liquefaction relief valves in well chambers
- At the base of well chambers, we improvised to install non-return valves with strengthened springs to reduce the damaging upward thrust from liquefaction immediately after earthquakes. We have since had a more permanent solution designed for us using burst disks, which we are deploying.