Shocks from water

Hiya, This has got me baffled!

I have a friend who has been getting electric type shocks when she washes in the morning. Not every day, but seems to be increasing in intensity over the last two months. She's been epileptic, grand mal, for the past three years. Her fits have also become more frequent over the last year.

Having looked at her plumbing, I can't see that she's getting shocks from that - ie the sink is isolated, and she stops the tap running before she puts her hands in.

Has anyone any experience or knowledge of this kind of thing - ie shocks form none electric sources, and not static electric shocks either - in people with epilepsy? Thanks :)