Drinking Water for New Zealand

Managed by ESR for the Ministry of Health.         Data extracted from the National DWO Database.
 

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Supply Details Explained

Use this page to understand the structure and details that are presented for each supply. for more on compliance, click here.

Note that only Networked, Bulk and RADWS supplies will be shown on this website. Self supply categories are not included.

Overview

The registration details for over 600 networked drinking-water supplies can be viewed on this website. Details are updated regularly from Drinking Water Online, the national database for New Zealand drinking water supplies.

The simplest supply for a community has a water source, a treatment plant (if treated), and a single distribution zone (the pipe network which delivers water to your property.) This would be structured in the Register as:

Supply 1

      Zone 1

            Plant 1

                  Source 1

This structure represents the small community in the diagram following.

Larger towns and cities often have several sources, plants and zones, all connected in various ways (move your mouse over the picture to see an example). As more parts are added, the Register entry for a supply lengthens, but the same line-by-line pattern is used. That is, for any zone you see listed, it receives water from the plant or plants listed under it, and the plants in turn are fed by the sources listed under them.

Supply schematic

The registration details include population and, optionally where supply population exceeds 500, a Public Health Grading. This consists of a single grading for each treatment plant (eg B) and a combined grading for each distribution zone (eg Ba).

What are Zones and Plants?

Distribution Zone: This is all or part of the town or community that receives similar quality water from its taps. If different parts of town have different water sources or conditions, then the supply will be divided into two or more zones. The emphasis is "each zone has similar quality water throughout" and therefore can be evaluated for compliance with the Standards.

Treatment Plant: A zone receives water from one or more treatment plants, which in turn receive water from one or more water sources (rivers, lakes, groundwater, etc.) If there is no physical treatment, for example with some groundwaters, a nominal treatment plant is still defined so this and other details can be recorded against its name.

Local Authority

The local authority shown is the territorial local authority for the geographic area within which the supply is located. While the local authority is normally the owner for city and town supplies, other supplies may be owned privately or run by public or community organisations. Therefore, the supplier is shown as a separate line.

 

Supply Details - Line by Line

Use this as an alternative approach to understanding a typical supply screen.

    EXAMPLE       EXPLANATION HERE

Sometown   –   Latest Published Compliance

« Uses the latest published Annual survey data.

District Health Board: Sometown DHB

« The public health unit that audits supplies in this region  
           
Component Code Name Population   Grading
Supply: SOM065 Sometown 24,680     « The supply for a town or city, etc. It has one or more zones, plants and sources.
      Supply category: Networked Supply   « Cities and towns have networked supplies. There are also bulk, self, specified-self and other types of supplies. This website shows network and bulk supplies.
      Local authority: Sometown City Council   « The territorial local authority for the locality. They may or may not be the supply owner.    
      Supplier: Sometown City Council   « The owner of the supply
 
  Zone: SOM065EA Sometown East 24,680   Bb « A distribution zone is the piping network (reticulation) in the streets of a town or locality. A zone should have similar water quality throughout. A small supply may have one zone, while large supplies can have many.
The optional grading here is A1 or A to E representing the plant that feeds the zone (or worst case plant if multiple plants), and an 'a1' or 'a' to 'e' for the zone itself.
      Test Zone for: NO3   « If a chemical or other determinand in the water is of potential health concern, then it is classified for that zone or plant as a 'Priority 2 determinand' and is listed here as something that must be regularly monitored.
      Compliance  as reported for 2015/16   « Uses data from the latest published Annual Report of Drinking-Water Quality for New Zealand.
       – Standards used: DWSNZ 2005   « Drinking Water Standards for New Zealand 2005 (Revised 2008)
       – Bacteria achieved: Yes   « Will fail if too many transgressions or if the sampling programme is inadequate.
       – Protozoa achieved: No   « Protozoa is not usually directly measured. Therefore will fail if treatment processes are inadequate for this type of water.
       – Chemical achieved: Yes     (NO3_ok)   « If any Priority 2 determinands have been assigned, then concentrations must be below the maximum acceptable value, and the sampling programme must meet requirements.
    Plant: TP06481 Sometown treatment plant     B « One or more treatment plants serve each zone. If no treatment is undertaken, a nominal plant is still defined. A plant can serve multiple zones in the same or different supplies. If this supply had two zones served by this plant, then the plant line here (and all of its source lines) would repeat under each zone.
The B is the plant and sources grade (see zone explanation above.)
    - Source: S01981   Sometown Dam       « Each plant receives water from one or more sources, which may be rivers, lakes, groundwater, etc.
    - Source: S01982   Westville River      
    - Source: S02023   Someother River      
             
    end of example        

 

The Public Health Grading

A water supplier can choose to have a supply graded,but it is not currently a requirement. More about grading.

Local Authority

The local authority shown is the territorial local authority for the geographic area within which the supply is located. While the local authority is normally the owner for city and town supplies, other supplies may be owned privately or run by public or community organisations. Therefore, the supplier is shown as a separate line.

 

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