Water can run through the pipes but volts can't run through anything. I take it you mean:
"I measured 93 volts between some pipes and something else"
If that other thing is a CPC or the MET or something supposedly earthed within the electrical installation, you've got two main possibilities:
a) The MET is earthed, but the pipes are not. Leakage from the installation to the pipes is raising their potential, possibly due to a disconnected CPC (in which case the leakage may be normal) or a fault from a cable to a pipe. Solution: find and fix the leakage source and / or missing CPC. Check whether the pipes should have been bonded anyway.
b) The pipes are earthed (or extraneous) but some or all of the installation is not. Leakage within the installation to the CPCs is raising part or all of the system to 93V above the potential that the pipes have found, but that's not immediately apparent as it's an equipotential and the problem is intermittent. However you should be able to catch it out with an abnormal N-E voltage soon enough. Solution: fix the broken CPC / EC / whatever.
A loose
neutral connection by itself won't make pipes live or the CPCs live relative to the pipes. OTOH, a high resistance connection in a
combined neutral/earth conductor could very well raise the potential of supposedly earthed bits by 93V w.r.t true earth. But then, the L-N potential would have to be 230-93 = 137V and I expect they would have rather obvious symptoms of flickering lights and appliances shutting down.
could be a phantom voltage
One would think the C/H system would have at least some earthed components so that it should not normally be floating, so this would fall into my category a) above.