**4.6.1 Taking the water sample**

The water to be examined should be taken into colorless, preferably glass cap bottles with a volume of 250 cm3 . Orifice and cap of the bottle are wrapped with separate papers and sterilized in the autoclave. If water will be taken from running water, the orifice of the tap is burned with spirit flame and the water is put into the bottle after leaving the water run for five minutes. The cap of the bottle is closed by caring the sterility conditions. To take water from the creek or river, the bottle is hold from the bottom, it is immersed into the water upside down to 30 cm deep. The orifice of the bottle is turned to the flow direction and water is filled with water without touching. To take water from dead water, lakes and depots, the bottle that a ballast was hung to the bottom and bounded with ropes from the neck and the cap is immersed into the water with a desired depth. The rope is pulled and the cap is opened, after the bottle is filled with water, it is pulled to up and the cap is closed. If a period more than 3 hours will pass from taking the water sample until the examination,

the bottle should be kept in ice. It may be sent to far places only in ice.

If sample will be taken from chlorinated water, chlorine should be neutralized immediately. For this, one sodium thiosulphate crystal is put into the bottle or 0,2 cm3 from 1 g of crystallized sodium thiosulphate solution which was dissolved in 100 cm3 sterile water before sterilization.

To mix the water well before the assay, the bottle that water sample is taken is shaken.
