Table V: Regional classification and relationship between CBVD and mean water hardness Regional CBVD % Of MEAN Mean Mean Hardness Location Disease Deaths [Ca] [Mg] Water Description in Decatur Mortality by (mg/l) (mg/l) Hardness County Rate Per CBVD (mg/l) NW 378.
Table VI gives the summary of correlation coefficient obtained when the mortality rates due to CBVD and concentrations of calcium, magnesium and hardness of waters are plotted in Figures 6A, 6B, 7A, 7B, 8A, and 8B for the drinking waters of Decatur County by regions.
4067) is observed between water hardness and the mortality rate from CBVD in all regions except for the southwestern area.
This region recorded the highest number of deaths caused by CVD and CBVD (Figures 3, 4 & 5).
It is observed that the incident of CVD and CBVD are the lowest in the county (Table V).
A statistically significant link between water hardness, calcium, magnesium and mortality from CBVD is demonstrated in our study (Table VI, Figures 6, 7 & 8) of Decatur County unlike the study (14) of North Dakota drinking waters where they only found a statistically slightly significant link between water hardness and geographical differences in mortality from CBVD.