A new water fountain was installed on the lawn outside the dining room. When one presses the tap, the water falls onto the body of the fountain fitting, flows down to the concrete base, from there onto the gravel, and then seeps down into the ground. Is it permissible to use this tap on Shabbat?
Watering a garden is forbidden on Shabbat, “de-oraita” (by biblical law, rather than rabbinical enactment), as it falls under the category of labor (melakha) known as “zore’a” – sowing (since the water helps the plants to grow), and also because of “horesh” – plowing (since the water softens the ground, potentially preparing it for sowing).
Someone who opens the tap in order to drink does not mean to water the grass or the nearby tree, but it is clear that some of the water will eventually reach the ground and will cause it to be irrigated. This situation is known as “psik reishia” (literally, “its head is cut off”: one cannot cut off a chicken’s head without causing it to die.) “Psik reishia” – an act that necessarily results in a melakha being performed – is forbidden on Shabbat, and therefore one may not wash one’s hands or play water games in the garden on Shabbat. In light of the above it would appear that the water fountain presents a similar problem. However, in this case the water does not fall directly onto the ground, but rather gets there via several stations along the way. An act that is not performed in a direct way is called “grama” (indirect causation). “Grama” is forbidden on Shabbat by rabbinical enactment.
In our case there is a combination of “grama” and an act that is not intended for the purposes of irrigation (“psik reishia”), and therefore one may use the tap for drinking on Shabbat. Rav Neuwirth, in his work “Shemirat Shabbat ke-Hilkhata”, (12, 18) writes: “If the water that pours into a basin flows through a pipe until it reaches the ground where plants are growing, one may wash one’s hands there on Shabbat, and it is likewise permissible to pour water into the basin for any other purpose, and there is no need to concern oneself with the irrigation of the plants that thereby occurs, if indeed that is not his intention. However, it is certainly forbidden to pour water onto plants, or any place that is sown or has anything growing in it, even if he does not meant to water the plants at all.”