Irresponsible to connect wall receptacle ground to a water
pipe. A wet human in a shower, bath, or touching water in a
sink is at greatest risk. And you would dump electricity into
those pipes? Shame on you. It is safer to not ground at all
rather than connect to water pipes. Even the code does not
permit this type connection any more. The only electrical
connection to water pipes is to remove electricity from those
pipes. Never dump electricity into water pipes.

Numerous reasons to never connect AC receptacle ground to
water pipes. Electricity in those pipes is more hazardous
than an outlet without safety ground. Sounds as if previous
owners replaced all two wire receptacles with three wire
receptacles without the necessary safety ground. Therefore
those screws would have no safety ground connection. These
receptacles are only safe (and legal) if powered through a
GFCI. And GFCI was one of two possible solutions provided in
another post.

Meanwhile, any recommendation to connect safety ground to
cold water pipes only creates a potentially greater hazard.

Ron Tock wrote:
That little screw that holds the outlet cover on should be grounded.
You could attach to that. Or a cold water pipe.