Chemical analysis - Wainuiomata

The following table shows the mean values of chemical analysis of the water supply from the Wainuiomata Water Treatment Plant, for the year ended 30 June 2018, 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

Median value

Max value

Alkalinity - total g CaCO3/m³

-

13

29

36

Aluminium - total g/m³

0.1 (B)

14

0.031

0.047

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)

11

29.455

33.000

Chloride g/m³

250 (B)

1

22.2

22.2

Chromium total g/m³

0.05 (A)

2

<0.001

<0.001

Conductivity at 25°C mS/m

-

1

15.6

15.6

Copper - total g/m³

2 (A)

13

<0.013

<0.013

Cyanide g/m³

0.6 (A)

2

<0.005

<0.005

Fluoride g/m³

1.5 (A)

103

0.49

0.91

Hydrogen sulphide g/m³

0.05 (B)

1

<0.05

<0.05

Iron - total g/m³

0.2 (B)

13

0.028

0.043

Lead - total g/m³

0.01 (A)

2

<0.001

<0.001

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

0.035

0.05

pH

7.0-8.5 (B)

14

7.507

7.7

Selenium - total g/m³

0.01 (A)

2

<0.005

<0.005

Silica g/m³

-

2

13.2

13.9

Sulphate g/m³

250 (B)

1

5.6

5.6

Total dissolved solids g/m³

1000 (B)

1

77

77

Zinc - total g/m³

1.5 (B)

13

<0.013

<0.013