Chemical analysis - Gear Island

The following table shows the mean values of chemical analysis of the water supply from the Gear Island 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. (C) Denotes that the results are from a sample point downstream of Gear Island Water Treatment Plant

 

Parameter

DWSNZ MAV (A) GV (B)

No of samples

Median value

Max value

Alkalinity - total g CaCO3/m³

-

1

72.000

72.000

Aluminium - total g/m³

0.1 (B)

2

0.018

0.018

Arsenic - total g/m³

0.01 (A)

2

<0.002

<0.002

Boron - acid soluable

-

2

<0.025

0.030

Cadmium - total g/m³

0.004 (A)

2

<0.001

<0.001

Calcium - Acid Soluble g/m³

-

2

13.625

17.4

Chloride g/m³

250 (B)

2

17.050

18.000

Chromium - total g/m³

0.05 (A)

2

<0.001

<0.001

Conductivity at 25°C mS/m

-

1

22.700

22.700

Copper - total g/m³

2 (A)

19

<0.013

0.015

Cyanide g/m³

0.6 (A)

2

<0.005

<0.005

Fluoride g/m³

-

-

-

-

Hydrogen sulphide g/m³

0.05 (B)

1

<0.05

<0.05

Iron - total g/m³

0.2 (B)

19

0.035

0.056

Lead - total g/m³

0.01 (A)

2

<0.001

<0.001

Manganese - total g/m³

0.04 (A)

19

<0.013

0.002

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

0.720

0.930

pH

7.0-8.5 (B)

1

7.500

7.500

Selenium - total g/m³

0.01 (A)

2

<0.005

<0.005

Silica g/m³

-

2

16.200

17.400

Sulphite g/m³

250 (B)

2

6.855

6.890

Total dissolved solids g/m³

1000 (B)

1

111

111

Zinc - total g/m³

1.5 (B)

19

<0.013

<0.013