Drinking water

Drinking water standards in New Zealand [2005]  {GV= Guideline value}

Determinand GV Units Comments
aluminium 0.10 mg/L Above this, complaints may arise due to depositions or discoloration.
ammonia 1.50.3 mg/L Odour threshold in alkaline conditions.For control of chloramine formation in chlorinated water.
calcium     See hardness.
chloride 250 mg/L Taste, corrosion.
chlorine 0.6–1.0 mg/L Taste and odour threshold (MAV 5 mg/L)
2-chlorophenol 0.00010.01 mg/L Taste threshold.Odour threshold.
colour 10 TCU Appearance.
copper 1 mg/L Staining of laundry and sanitary ware (PMAV 2 mg/L)
1,2-dichlorobenzene 0.0010.002 mg/L Taste threshold.Odour threshold (MAV 1.0 mg/L)
1,4-dichlorobenzene 0.00030.006 mg/L Odour threshold.Taste threshold (MAV 0.4 mg/L)
2,4-dichlorophenol 0.00030.04 mg/L Taste threshold.Odour threshold.
ethylbenzene 0.0020.08 mg/L Odour threshold.Taste threshold (MAV 0.3 mg/L)

hardness (total)

(Ca + Mg) as CaCO3



mg/L High hardness causes scale deposition, scum formation.  Low hardness (<100) may be more corrosive.Taste threshold.
hydrogen sulphide 0.05 mg/L Taste and odour threshold.
iron 0.2 mg/L Staining of laundry and sanitary ware.
magnesium     See hardness.
manganese 0.040.10 mg/L Staining of laundry.Taste threshold (MAV 0.4 mg/L)
monochlorobenzene 0.01 mg/L Taste and odour threshold (MAV 0.3 mg/L)
odour (threshold odour number) 3   Odour should be acceptable.
pH 7.0–8.5   Should be between 7.0 and 8.0.  Most waters with a low pH have a high plumbosolvency.  Waters with a high pH: have a soapy taste and feel. Preferably pH <8 for effective disinfection with chlorine.
sodium 200 mg/L Taste threshold.
styrene 0.004 mg/L Odour threshold (MAV 0.03 mg/L)
sulphate 250 mg/L Taste threshold.
taste     Should be acceptable to most consumers.
temperature     Should be acceptable to most consumers, preferably cool.
toluene 0.030.04 mg/L Odour.Taste threshold (MAV 0.8 mg/L)
total dissolved solids 1000 mg/L Taste may become unacceptable from 600–1200 mg/L.
trichlorobenzenes (total) see below   (MAV 0.03 mg/L)
1,2,3-trichlorobenzene 0.01 mg/L Odour threshold.
1,2,4-trichlorobenzene 0.005 mg/L Odour threshold.
1,3,5-trichlorobenzene 0.05 mg/L Odour threshold.
2,4,6-trichlorophenol 0.0020.3 mg/L Taste threshold.Odour threshold (MAV 0.2 mg/L)
turbidity 2.5 NTU Appearance.  For effective terminal disinfection, median turbidity <1 NTU, single sample <5 NTU.
xylene 0.02 mg/L Odour threshold (MAV 0.6 mg/L)
zinc 1.5 mg/L Taste threshold.  May affect appearance from 3 mg/L.

Maximum acceptable values (MAV) for microbial determinands

Micro-organism MAV 1
Escherichia coli (E. coli) 2 Less than 1 in 100 mL of sample
viruses No value has been set due to lack of reliable evidence
total pathogenic protozoa Less than 1 (oo)cyst per 100 L of sample