In addition to DOM content, the other major difference between unaltered
SNARC and WARU water was the concentration of divalent cations.
As described above,WARU water was pumped from a region of the
Sparta Sand Aquifer known to yield very softwaterswhereas the SNARC
waterwas pumped froma region yieldingwaters ofmoderate hardness
(Table 1). Divalent cations, in particular dissolved calcium, are known to
affect bacterial adhesion to inert and living surfaces