Water
In PE's FirstView, water is shown "spacefilled", that is with atoms rendered as spheres of van der Waals radii.

Water oxygen atom (hydrogens absent)

Water molecule
Don't see any water? Click on the button several times. If no red atoms appear/disappear, then the PDB file you loaded doesn't specify the positions of any water molecules.
You can confirm this by looking in the message box below after you click the button. If it says "No atoms selected!" immediately above or below "select water", then no water molecules were assigned coordinates in this PDB file.

In PDB files resulting from X-ray crystallography that do specify water positions, typically only 10-20% of the water that was actually present in the crystal is shown. Protein crystals used for X-ray diffraction are about half water, but the majority of the water present is disordered and cannot be resolved. Only tightly bound, stationary water molecules can be experimentally resolved. Similarly, in PDB files resulting from NMR, only tightly bound water can be resolved, and the majority of the water is not represented.

Most protein crystals lack sufficient regularity ( resolution) to permit resolving hydrogen atoms, so in most PDB files, hydrogen atoms are absent. Sometimes hydrogens are added by modeling. Hydrogens are always present in PDB files resulting from NMR analysis, and usually present in theoretical models. To find out whether this PDB file is the result of X-ray diffraction analysis, NMR, or theoretical modeling, look for the Method shown on PE's Features of the Molecule control panel (coming up after FirstView, or always available from the PE Site Map).