Why did the Sages decree that someone immersed in drawn water becomes a secondary derivative?
Halacha 1: people would immerse carelessly in foul cave water, then rinse with clean drawn water, and conclude that the drawn water was what purified — so the Sages decreed drawn water actually imparts impurity.
Question 2
Three lugim of drawn water come from four different containers in succession. Do they combine to impart impurity?
Halacha 2: only up to three containers can be combined; if the water came from four containers, they do not combine — even if each flow began before the previous stopped.
Question 3
Why did the Sages decree that Holy Scriptures defile hands?
Halacha 5: the Sages decreed this to stop the practice of placing terumah loaves next to scrolls — because mice would ruin the scrolls. By making scrolls defile terumah, people would stop placing food next to them.
Question 4
A Torah scroll written entirely in the ancient Ivri (Paleo-Hebrew) script — does it defile hands?
Halacha 7: Scripture must be written in the Ashurit script on parchment with ink to defile hands. Writing in Ivri script does not qualify.
Question 5
After immersing from drawn-water impurity (a Rabbinic decree), must one wait until nightfall to be fully pure?
Halacha 1: since drawn-water impurity is fundamentally Rabbinic, immersion alone purifies without requiring waiting until nightfall (no haarev shemesh needed).