Q. Reese asked:
Why isn't all the water in wells and cisterns prohibited due to Giluy? I can't imagine that wells were covered constantly; besides, the rainwater cisterns and wells must have been open to be filled with rain?
Thanks!
Q. Reese, Atlanta, GA
The Kollel replies:
Dear Q. Reese,
Hello there and thanks for your interesting question. The Mishnah in Terumos (8:5) gives guidelines for the issue you raised. If there is enough water to dissolve the venom there is no problem of Giluy. In the case of a spring, any amount is enough to dissolve the venom.
This is also the ruling of the Rambam in Hilchos Rotze'ach (11:12-13).
Kol tov.
Y. Landy