Access to safe drinking-water

This factsheet 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 bacteriological, protozoal and chemical compliant water. 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 (83%) 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% (3.9 million) were served with bacteriological-compliant drinking-water, 79% (3.2 million) with protozoal-compliant drinking water, and 98% with chemically compliant drinking water (4 million). About 76% (3.1 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 3,885,000 95.3
Protozoal compliance 3,209,000 78.7
Chemical compliance 3,975,000 97.5
Overall compliance 3,107,000 76.2

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.

Overall compliance in 2018–2019 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, 2010–2019

 Fig1

Note:  Tighter requirements for monitoring came into effect from 1 August 2019. However, these changes will affect the coming reporting period (i.e. 2020–21) (Ministry of Health 2020).

Source: Ministry of Health [1]

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

Sixty-three percent of the population served by small drinking water supplies received water that met the bacteriological standards, compared to 98.5% of the population served by large supplies. Protozoal compliance also increased with supply size, from 30.7% for small supplies to 83.7% 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, 2018-2019

Fig2

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, mostly outside of the 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 near the Taupo Volcanic Zone (Figure 5). The most common determinant in this area was arsenic, for which the MAV was exceeded in 7 supplies, affecting 9,101 people. Arsenic can occur from natural geologic sources and is associated with elevated risk of some cancers [2]. Elsewhere, disinfection by-products (13 supplies; 72,151 people) and fluoride (4 supplies; 19,644 people) were the most common determinants associated with failure to meet the chemical standards. These failures include exceedances of the MAV and monitoring issues.

 

Figure 3: Percentage of population with access to bacteriological-compliant drinking water by territorial authority and supply, 2018–2019


 Source: Ministry of Health [1]

Figure 4: Percentage of population with access to protozoal-compliant drinking water by territorial authority and supply, 2018 –2019 


Source: Ministry of Health [1]

 

Figure 5: Percentage of population with access to chemically compliant drinking water by territorial authority and supply, 2018 –2019


 

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. This describes the access to safe drinking water for 4.1 million New Zealanders (83%)[1].

References

  1. Ministry of Health. 2020. Annual Report on Drinking water Quality 2018–2019. 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.

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