From a letter by Father John, a Russian monk, written to a lay person (1947):

I received your cordial note.  I was happy with your last words: ‘I am not troubled at all, but peaceful’.  According to the Holy Fathers, that is how it should be: if you falter in some virtue, you must not tremble; if you fall–get up; if you fall again, get up again; and so on till the final hour of death.  O Lord, glory to thy mercy.  Great is thy goodness, that Thou has given repentance to us sinners, for Thou didst come to earth not for the righteous, but for us sinner.

You did draw up pure water, but a toad had unexpectedly got into the well.  Throw it away and the life-giving water will still be pure.