I had just moved in to an upstairs apartment in an old building. Attempting to take a bath that evening, (old building, no shower) I felt like I was being electrocuted as I stepped into the tub. I later measured 90VAC from the faucet to the drain. Later that week, when talking to my new downstairs neighbor, she told me her dog would bark to tell her the phone was ringing. He was chained to the outside water faucet and his feet would get tickled when ringer voltage came in on her line.
Bottom line is that even when it was code, grounding to the water pipes was a bad idea. Even if you make it work well, at best you have an "improved bad idea", code or not.
The reason for the voltage present on the cold water pipes is because the telephone company connected its ground to the water pipes when the house was built. With the passing of the years, its all too possible that the ground connection from the plumbing to the ground rod was removed--or more likely that the incoming water main pipe was replaced with plastic.
In other words, the water pipe ground was removed and never replaced--which is against code. The fix is obvious--reconnect the ground or drive in a ground rod and reconnect the ground that was removed from the old water pipe.
You do not remove or eliminate protection--and yet the city/town water department does it all the time during mains replacement. Their excuse--that that isn't their job--is a poor excuse for potentially killing someone.
