Chukat - Sheini
The Death of Miriam
A person who is ritually pure is to dip some hyssop into the water and sprinkle it on the contaminated people, as well as on the tent and the utensils that were in it. Anyone who came in contact with a corpse or a grave would need to be so purified. The sprinkling is done on the third and seventh days, then the contaminated person immerses himself and his clothes in a mikvah and becomes pure at nightfall. One who touches this water outside of the purification process would actually become impure and require immersion.
A person who becomes ritually impure by corpse contamination transmits a lesser degree of impurity to others.
Fast forward 38 years: In the final year in the desert, in the month of Nisan, Miriam died and was buried. The Jews had enjoyed a well in desert in the merit of Miriam. Once she died, this well went away. The people complained to Moshe.
"Why did you bring us here?" they griped. "Here in the wilderness, we never had fruit and now we don't even have water!" Moshe and Aharon prayed to G-d, Who answered them.