Access to safe drinking-water

This indicator presents statistics on the population who have access to safe drinking-water in New Zealand. Access to safe drinking water is measured by access to drinking-water that complies with bacteriological, chemical and protozoal standards.. Boil-water notices may be issued to residents if there is a risk of microbial contamination in drinking water.

About three-quarters of New Zealanders on registered supplies received drinking water that met all the requirements of the Standards

About 4.1 million New Zealanders (81.4% of the population) were served water from registered drinking water supplies during the 2018–2019 reporting period. The remainder of the population received drinking water from very small community supplies and self-supplies, e.g. rainwater tanks.

Of the population on registered supplies, 95.2% (3.9 million) were served with bacteriological-compliant drinking-water, 80% (3.3 million) with protozoal-compliant drinking water, and 99.1% with chemically compliant drinking water (4.09 million). About 77% (3.2 million) received drinking water that met all three requirements (Table 1).

Table 1: Population on registered community drinking water supplies that had access to safe drinking water, 2018–2019

Access to safe drinking water Estimated population Percent
Bacteriological compliance 3,924,540 95.2
Protozoal compliance 3,311,419 80.0
Chemical compliance 4,094,610 99.1
Overall compliance 3,246,369 78.6

Source: Ministry of Health [1]

 

Chemical and bacteriological compliance has remained at or above 95% from the 2010–2011 reporting period onwards. Protozoal compliance was highest (83%) in 2016–2017, before dropping to its lowest (75%) in 2017­–2018 due to several large supplies losing ‘secure bore water’ status.

Overall compliance in 2019–2020 improved from the previous reporting period; however, it remained lower than its peak (81%) in 2016­–2017 (Figure 1).

Figure 1: Percentage of population on registered community drinking water supplies with access to safe drinking water, 2010–2020

 Fig1 v2

Source: Ministry of Health [1]

Small drinking water supplies less likely to meet protozoal and bacteriological standards compared to large supplies

Sixty-five percent of the population served by small drinking water supplies received water that met the bacteriological standards, compared to 98.8% of the population served by large supplies. Protozoal compliance also increased with supply size, from 39.9% for small supplies to 85.9% for large supplies. Chemical compliance was ≥ 90% across all supply sizes (Figure 2).

Compliance costs per capita are likely higher for smaller supplies compared to larger supplies (Ministry of Health 2020).  Small supplies tend to be in rural areas, while the largest supplies tend to serve New Zealand’s largest cities.

Figure 2: Percentage of population with access to bacteriological compliant drinking water by territorial authority, 2019-2020

SuppSize

Source: Ministry of Health [1]

 

People in the North Island were more likely to be supplied with protozoal-compliant drinking water than those in the South Island

Bacteriological compliance was low for some supplies, primarily outside major urban areas (Figure 3). Protozoal compliance was low for supplies located in rural areas, particularly in the South Island (Figure 4). Chemical compliance was lowest in the Central North Island, with several incompliant supplies near the Taupo Volcanic Zone (Figure 5). The most common determinand in this area was arsenic, for which the Maximum Acceptable Value was exceeded in seven supplies, affecting 9,093 people. Arsenic can occur naturally in soil or water due to geothermal activity (Robinson et al 2004) and is associated with an elevated risk of some cancers (Smith et al 1998). Elsewhere, excessive levels of, or failure to adequately monitor, by-products of the chemicals used to disinfect drinking-water resulted in 13 supplies failing to comply, affecting 45,560 people.

 Figure 3: Percentage of population with access to bacteriological-compliant drinking water by territorial authority and supply, 2019–2020

Fig3

Source: Ministry of Health [1]

Figure 4: Percentage of population with access to protozoal-compliant drinking water by territorial authority and supply, 2019 –2020 

Fig4

Source: Ministry of Health [1]

 

Figure 5: Percentage of population with access to chemically compliant drinking water by territorial authority and supply, 2019 –2020

Fig5

 Source: Ministry of Health [1]

 

Information about this indicator

The datasets for this indicator come from the Ministry of Health Annual on drinking water quality reports.  Drinking water statistics are presented for all registered community drinking water supplies that served more than 100 people.

References

  1. Ministry of Health. 2021. Annual Report on Drinking water Quality 2019–2020. Wellington: Ministry of Health.
  2. Smith, A H, Goycolea, M, Haque, R, & Biggs, M L. 1998. Marked increase in bladder and lung cancer mortality in a region of Northern Chile due to arsenic in drinking water. American journal of epidemiology, 147(7), 660-669.

  3. Robinson B, Clothier B, Bolan N, Mahimairaja S, Greven M, Moni C, Marchetti M, Dijssel C, Milne G. 2004.
    Arsenic in the New Zealand environment. URL: https://www.researchgate.net/publication/228591523_Arsenic_in_
    the_New_Zealand_environment (accessed 6 August 2021)
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