How can Holy water be tainted?

holy water can certainly be disrespected and desecrated....throwfeces in it, spit on it, urinate in it....but it can never lose its potency....it has been blessed by the power of the holy spirit....even satanic acts and witchcraft can do it no harm....for god is infinitely more powerful than satan and his minions.....im not saying stick ur hand in it if acid or toxic chemicals are in it although i believe miracles are certainly possible with significant faith and/or direct divine/saintly intervention