The following table shows the mean values of chemical analysis of the water supply from the Te Marua Water Treatment Plant, from 1 July 2019 - 30 June 2020, compared with the maximum allowable value (MAV) or guideline value (GV) for each element as set out in the Drinking Water Standards New Zealand (DWSNZ).

Notes (A) MAV denotes the maximum acceptable value to comply with the Drinking-water Standards. (B) GV denotes the maximum guideline value in the Drinking Water Standards

Parameter

DWSNZ MAV (A) / GV (B)

No of samples

Mean value

Max value

Alkalinity - total CaCO3/m3

-

13

29

35

Aluminium - total g/m3

0.1 (B)

13

0.030

0.19

Arsenic - total g/m3

0.01 (A)

2

<0.002

<0.002

Boron - total g/m3

1.4 (A)

2

<0.05

<0.05

Cadmium - total g/m3

0.004 (A)

2

<0.001

<0.001

Calcium hardness g CaCO3/m3

200 (B)

13

17.230

20

Chloride g/m3

250 (B)

1

9.68

9.68

Chromium - total g/m3

0.05 (A)

2

0.022

0.022

Conductivity at 25oC - mS/m

-

1

10.3

10.3

Copper - total g/m3

2 (A)

13

0.019

0.029

Cyanide g/m3

0.6 (A)

2

<0.005

<0.005

Fluoride g/m3

1.5 (A)

106

0.351

0.76

Hydrogen sulphide g/m3

0.05

1

<0.05

<0.05

Iron - total g/m3

0.2 (B)

13

0.022

0.034

Lead - total g/m3

0.01 (A)

5

0.0086

0.021

Manganese - total g/m3

0.04 (A)

13

<0.013

<0.013

Mercury - total g/m3

0.007 (A)

2

<0.001

<0.001

Nickel - total g/m3

0.08 (A)

2

<0.001

<0.001

Nitrate - nitrogen g/m3

50 (A)

2

0.03

0.03

pH

7.0 - 8.5 (B)

14

7.692

7.8

Selenium - total g/m3

0.01 (A)

2

<0.005

<0.005

Silica g/m3

-

2

9.27

9.81

Sulphate g/m3

250 (B)

1

3.17

3.17

Total dissolved solids g/m3

1000 (B)

1

51

51

Zinc - total g/m3

1.5 (B)

13

0.099

0.158