718. A Channel of Water in a Courtyard

Shabbos 15:12

If a channel of water that passes through a courtyard is wider than ten cubits (about 15’), we may not draw water from it on Shabbos unless a partition is erected where it enters and exits the courtyard. This applies even when the channel is less than ten handbreadths deep (30”). Since it is wider than ten cubits, it is like a breach that nullifies a wall. As far as carrying in the rest of the courtyard as a whole, if even a small section of the wall remains on each side of the opening, or if a section of wall four handbreadths wide (about 1’) remains on one side, it is permitted to carry throughout the courtyard; it is only prohibited to draw water from the channel. However, if none of the wall remains, it is prohibited to carry throughout the courtyard because it has been breached to the sea, which is a carmelis.

Shabbos 15:13

Here’s how the partitions are erected: if most of the partition is above the water, at least a handbreadth (about 3”) must descend into the water. If most of the partition is below the water, at least a handbreadth must extend above the water. This causes the water in the courtyard to be distinct from the water on the opposite sides of the partitions. Even though these partition do not reach the ground, they are effective because they are ten handbreadths tall. A hanging partition is only permitted when it comes to water. Carrying this water is only prohibited by rabbinic degree, so the Sages were lenient when it came to the partitions necessary to distinguish the water.