At each sampling station, that is, wells or river, a composite
sample that was made from mixing three sub-samples was
collected. One litre plastic sampling bottles were prepared by
thoroughly rinsing them with distilled water in the laboratory
before sampling was done. Before each sample was collected,
plastic sample bottles were rinsed twice with the same sample
water. Three 300 ml water samples were collected using a 500 ml
measuring cylinder which was first rinsed twice with the same
sample water.