This study evaluates the sanitary conditions of ten selected roof water tanks in Alkharj Governorate,
KSA and examines their water quality. A survey was conducted using a questionnaire to collect information about the
sanitation of these tanks. The physical, chemical and biological parameters of 60 water samples were examined using
standard methods. The survey results revealed that 40% of tanks received unsatisfactory grades. The physical and
chemical analyses indicated that the turbidity and levels of residual chlorine were above the maximum permissible

Chromosomes can be structurally identified by their sizes, positions of centromeres
and nucleolar organizers, and patterns of chromomeres, heterochromatin,
and bands. There are four types of aberrations in the chromosomal structure such
as deletions, duplications, inversions, and translocations which can be detected
cytologically under the microscope. Some changes are however too subtle to be
detected cytologically. Deletions represent missing segments of chromosomes.
The homozygous deletions can be lethal, whereas heterozygous deletions can be