In Mishnah 11 of the second chapter of Tractate Bava Basra, as well as in the four mishnayos that conclude the chapter, the Mishnah discusses trees that cause a nuisance to neighbors. The first case: A person's neighbor has a cistern for storing water, and the person wishes to plant a tree in his courtyard close to that cistern. The problem lies with the tree's roots - the concern is that they will spread into the neighbor's property, puncture or crack the walls of the cistern, and cause leakage and damage.
The Distances Prescribed by the Mishnah:
"Marchikin es ha'ilan min habor esrim vechamesh amah" - one must distance the tree from the cistern twenty-five amos. This is the required distance between the location where the tree is planted and the neighbor's cistern, out of concern that the roots will spread and cause damage.
"Uvecharuv uveshikmah chamishim amah" - and for a carob and a sycamore, fifty amos. For larger trees, such as the carob and the sycamore, the Tanna Kamma extends the distancing requirement to fifty amos.
"Bein milma'lah bein milmatah min hatzad" - whether from above or from below at the side. It makes no difference whether the tree is situated higher than the cistern or lower than it, since the roots are liable to descend to the upper part of the cistern or rise through its bottom. In any case, the problem exists, and therefore a distance of twenty-five amos is required, and for a carob and a sycamore, fifty amos.
Which Came First - The Cistern or the Tree:
The cistern came first: If the cistern was in its place first, it turns out that the planter of the tree acted improperly, as he was not permitted to place it within twenty-five amos. Therefore, "kotzetz venosein damim" - he must cut down the tree, but the owner of the cistern must compensate him for the loss of the tree.
The tree came first: If the tree was planted first, and only afterward did the neighbor dig his cistern within twenty-five amos - "lo yakutz" - he need not cut it down. The owner of the cistern has no right to demand the cutting down of the tree, since he is the one who chose to dig there, and he must bear the consequences.
"Safek zeh kadam safek zeh kadam": When it is not known which came first, the tree or the cistern - "lo yakutz" - he need not cut it down. As in any monetary doubt, the rule is that the burden of proof rests on the claimant, and the burden of proof rests on the one demanding the cutting of the tree. Since the owner of the cistern cannot prove his claim, he does not have the power to force the cutting.
This law seemingly contradicts what was learned in Mishnah 7, where it was established that one who plants with permission receives compensation, whereas one who plants without permission does not receive compensation. Here, the person planted without permission, as it is forbidden to plant so close to his friend's cistern, and nevertheless, he is entitled to compensation. The difference is between one who plants in his own courtyard and damages his neighbor who is a private individual, and one who plants on the outskirts of the city and damages the public: the public has more rights than an individual. The individual is indeed permitted to claim that the tree causes him a nuisance, but he is obligated to pay the value of the lost tree.
The Approach of Rabbi Yosi:
Thus far are the words of the Tanna Kamma, which is the approach of the Sages. Rabbi Yosi, whose approach we have already seen in the past, disagrees according to his general method. The foundation of his approach: one who acts within his own domain is permitted to do with it as he pleases, and he is not required to be careful regarding his neighbor's property. A person who wishes to plant a tree in his courtyard, and his neighbor has a cistern - that is the problem of the cistern's owner. The planter is doing a reasonable action in his own property, and he has the full right to do so; and if the matter bothers the neighbor, the neighbor must solve the problem.
Yet even here, Rabbi Yosi admits that in a case of "girei dilei" - a person's arrows - the action is forbidden. Just as a person is not permitted to shoot harmful arrows, so too he is forbidden from doing an act that causes his neighbor direct and immediate damage. However, with planting a tree this is not the case: only in another ten years are the roots liable to spread and cause damage, and this is not the planter's problem.
Therefore, Rabbi Yosi says: "Af al pi shehabor kodemes la'ilan - lo yakutz" - even though the cistern precedes the tree, he need not cut it down. Even if the water cistern was in its place first, and only afterward did his friend plant the tree in his courtyard, the planter is not obligated to cut it down. And his reason is: "Shezeh chofer besoch shelo vezeh notei'a besoch shelo" - for this one digs within his own and this one plants within his own. This one dug his cistern in his courtyard, and that one planted his tree in his courtyard, and each is permitted to do in his own property as he pleases. There is no immediate damage to the other here and there are no "girei dilei" here, and the injured party must do what is necessary to protect himself.
Regarding the cistern, as we will see in the next mishnah, the owner of the cistern is permitted to cut within his own domain: he is permitted to cut the roots that penetrate his property and endanger his cistern. But to force his neighbor to cut down his tree - this is not in his power.
The Halachah:
The halachah follows Rabbi Yosi: a person may do as he pleases in his own courtyard, unless he causes 'giri dileih' - direct and immediate damage to his neighbor. This is not the case when planting a tree near a cistern, and therefore a person may plant his tree in his courtyard, and in practice, there is no need to distance it twenty-five amos. However, the owner of the cistern is permitted to cut the roots that invade his property and cause concern for damage to his cistern.