Water testing

 

Taking the water sample

Correct sampling, storage and transportation are critical to the accuracy of analysis.  Samples should be collected carefully to make sure the most representative sample possible is obtained – well mixed flowing water where possible.  Use only clean containers for collecting samples, these are provided free of charge with analysis and can be picked up from MPL.

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General and Potable Waters and Inorganic Analysis

Samples for drinking water supplies should ideally be taken at both the source of supply and at a tap commonly used.  The water should be allowed to run for several minutes to flush the system and the sample container should be flushed with water before collecting the sample.  Water samples from wells/bores should be collected after the pump has run long enough to deliver water representative of ground water; this will avoid collection of stagnant water.

Plastic bottles are normally sufficient for this type of sampling.  A 500mL sample is required which should be filled to the top to exclude air, forwarded for analysis within 24 hours and kept cool if possible.

Other specific analysis types (eg microbiological or organics analysis) require different sample bottles as given below in the sample preservation information.

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MPL Drinking water testing (DWA)                       

500mL unpreserved plastic bottle

Analysis includes pH, Electrical Conductivity, Total Dissolved Salts, Sodium, Potassium, Calcium, Magnesium, Cadmium, Copper, Iron, Manganese, Lead, Chloride, Sulfate, Nitrate, Nitrite, Bicarbonate, Carbonate and Hydroxide.  Results are reported versus Australian Drinking water guidelines.

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MPL Extended water testing (EWA)                       

500mL unpreserved plus 100mL glass bottle specially preserved for mercury

Analysis includes all parameters listed for DWA plus Aluminium, Boron, Barium, Beryllium, Cobalt, Chromium, Molybdenum, Nickel, Silicon, Strontium, Titanium, Vanadium, Zinc, Arsenic, Mercury and Selenium.

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MPL Potable water testing (DWA + Standard Micro)                   

500mL unpreserved plastic bottle and 500mL plastic sterilised (for Microbiological)

Standard Micro covers analysis for Total Plate Count, Thermotolerant Coliforms, Faecal Streptococci and E Coli.  Results for all analysis given versus drinking water guidelines.

It is important to use the correct containers.  If not the analysis may be adversely affected.

IMPORTANT:  Do not rinse sample bottles containing preservative prior to sampling.

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Sample preservation details

 

ANALYTE	CONTAINER	PRESERVATIVE	TRANSPORTATION
TKN	Polythene	None	Transport chilled to lab. 24 hours
pH, EC, Alkalinity	Polythene	Fill to exclude air	Transport Chilled to lab ASAP
BOD,COD, Total N, Total P, NH3,NO2, NO3, TKN	Polythene	Fill to exclude air	Store at 1 to 4 oC, to lab within 24 hrs
Oil & Grease	Glass 500mL	None	Refrigerate. 24 hours
Volatile Organics	Glass 2 x 40mL	Acidify with Sulphuric acid	Refrigerate
Total Petroleum Hydrocarbons	Glass 500mL and Glass 2 x 40mL	None Acidify with Sulphuric acid	Refrigerate
Other Organics (PAH, OCP/OPP)	Glass 500mL	None	Refrigerate
B, Br, Cl, K, Ca, Na, F, Si, TDS, Turbidity,SO4,	Polythene	None	None. TPD, Turbiidty transport in 24 hours. All other analytes 1 month
Al, As, Ba, Cd, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Ni, Se, Zn	Polythene	Acidify with 1mL HNO3 to pH<2	None. Transport within 1 month.
Mercury	Brown Glass 100mL	Acidify with HNO3/K2Cr2O7	None. Transport to lab within 1 month
Sulphide	Polythene	Field Filter and preserve with zinc acetate/NaOH	Store at 1 to 4 oC, transport to lab within 1 week
Ferrous	Polythene	Field filter and acidify with HCl.  Exclude air	Receive within 24 hours
Legionella	Sterile PET	Sodium thiosulphate	Store at 1 to 4 oC, to lab within 24 hrs
Bacterial (micro testing)	Sterile PET	Sodium thiosulphate	Store at 1 to 4 oC, to lab within 24 hrs
Amoeba	Sterile PET	Sodium thiosulphate	Store at ambient temperature. Transport to lab within 24 hours
Cyanide Species	Black Polythene	Adjust pH to>11.5 with NaOH, if H2S present add PbCO3	Store at 1 to 4 oC, to lab within 24 hrs
TOC	100mL Glass	None	Transport Chilled to lab within 1 week.
Iodide	500ml amber Glass	None	Refrigerated transport. 24 hours

For routine analysis suites:

DWA suitable in a ‘Green’ 500mL Label bottle.

EWA requires an unpreserved ‘Green’ 500mL bottle, ‘Red’ 250mL bottle for metals analysis and a 100ml brown glass mercury bottle.

Standard Micro samples require a ‘Blue’ Label 500mL Micro bottle.

For testing of oil and grease and TRH (Hydrocarbons) or other organics, two separate glass bottles are required as the entire sample (500mL) is used for each analysis.

For further information refer to the APHA handbook and AS/NZS 5667.1.