Eiruvin 2:3-4

Eiruvin 2:3

Rabbi Yehuda says that the maximum distance that the enclosing boards may be from a well is a beis sasayim (5,000 square cubits – approximately 11,000 square feet). The Sages replied that the measurement of a beis sasayim is only relevant in the cases of a garden and a storage yard. When it comes to a sheep fold, a cattle corral, a back yard and a courtyard, even an area of five kor or ten kor is permitted. [For context, a beis sasayim is large enough to plant two seah of seed; five kor is enough land to plant 150 seah of seed and ten kor is enough to plant 300 seah of seed.] Accordingly, it is permitted to distance the boards as far away from the well as one likes as long as one keeps increasing the number of boards.

Eiruvin 2:4

Rabbi Yehuda says that if a public road passes between the boards enclosing a well, it should be diverted around them, though the Sages say that this is unnecessary. It makes no difference whether one is enclosing a public cistern (i.e., collected water), a public well or a private well, the system of boards we have described is employed. If one is enclosing a private cistern, he must erect a partition ten handbreadths tall (about 30”); this is the opinion of Rabbi Akiva. Rabbi Yehuda ben Bava says that the boards are only used to enclose a public well; the other wells and cisterns require a partition of ten handbreadths.