A total of 13 samples were collected in 1 L acidwashed polyethylene bottles from local families at random to represent the whole area, and 2 samples were collected from the school to avoid the differences in environment and use of pipe.
A total of 13 samples were collected in 1 L acidwashed polyethylene bottles from local families at random to represent the whole area, and 2 samples were collected from the school to avoid the differences in environment and use of pipe.