A well head is the physical structure at the top of the well that connects to the water supply network.

The Council has 104 wells with below-ground well heads and 36 wells with above-ground well heads. All new well heads are built above ground to improve the resilience and safety of the wells and the security of the water supply.

In order for groundwater to be provided without the need for treatment such as chlorination, three criteria must be met:

  1. The bore water must not be directly affected by surface or climatic influences (i.e. the water is at least a year old, by which time any pathogens will have died)
  2. The well head must provide satisfactory protection to prevent contamination of the water supply
  3. E. coli must be absent in the bore water.

The Council is upgrading its well heads so they meet the interpretation of the standard required to meet criteria 2 above. Once well heads are secure, temporary chlorination can stop at that pump station.

All new well heads are built above ground.

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Below- and above-ground well heads

Work timeframes

You can find the latest information about work timeframes by viewing our progress map(external link).

Making sure there's enough water while we upgrade

Demand for water fluctuates depending on the season and at different times of the day. We need to provide enough for people’s basic needs, as well as for emergencies such as firefighting.

While we work on a well head to upgrade it, we can’t use water from it. We have to carefully consider where we do maintenance and upgrades so we can continue to provide enough water to all parts of the city.

Our analysis has led to an initial programme of work that, once completed in May 2019, will provide enough unchlorinated water to meet typical demand over winter. If demand goes above this level, we may need to use the other sites and that water will need to be treated with chlorine.

Favouring supply from above-ground well heads

Some pump stations are supplied by a mix of below-ground and above-ground well heads. We intend to upgrade the above-ground well heads so they are secure. We will also isolate the below-ground well head so no water is being taken from it. This means water from these pump stations will not be chlorinated, including while any further work is done on the below-ground well head, such as bringing it above ground or drilling a new well.

The pump stations where this is planned are:

  • Grampian
  • Farrington
  • Hills
  • Burnside
  • Lake Terrace
  • Thompsons
  • Woolston