Short answer. Yes. Article 674 of the Civil Code obliges every building owner to construct the roof so rainwater falls on their own land, or on a street or public place, and not on a neighbor's land. Even water that lands on your own property must still be collected so it does not damage the land next door.
What the law says
The owner of a building shall be obliged to construct its roof or covering in such manner that the rain water shall fall on his own land or on a street or public place, and not on the land of his neighbor
Civil Code, Article 674 — Rain Water From Roofs. Read the full provision →
The core obligation
Article 674 states the duty in mandatory terms: the owner of a building shall be obliged to construct its roof or covering in such manner that the rain water shall fall on his own land or on a street or public place, and not on the land of his neighbor. The obligation attaches to the owner of the building, not to whoever happens to be occupying it, and it is framed around how the roof is built rather than around any single rainfall event. A roof designed or pitched so that water sheds onto neighboring land does not comply, however the building itself is otherwise situated.
It applies even where several people own the adjoining land
The article extends the duty to a specific complication: even though the adjacent land may belong to two or more persons, one of whom is the owner of the roof. In other words, part-ownership of the neighboring land by the same person who owns the roof does not create an exception. The roof still has to be built so that its runoff does not land on that neighboring property, regardless of who else has a stake in the roof owner's own building or in the land beside it.
The duty does not stop once the water lands on your own side
Article 674 adds a second sentence that goes further than simply redirecting the drip line: even if it should fall on his own land, the owner shall be obliged to collect the water in such a way as not to cause damage to the adjacent land or tenement. So keeping the runoff technically on your own property is not, by itself, the end of the obligation. If that collected water then seeps, pools, or flows over onto the neighbor's land or building and causes damage, the owner is still answerable for that outcome under this same article.
What this means for an existing roof
If your roof currently sheds water toward a neighbor's property, the article gives your neighbor a basis to insist you change it, and it gives you a basis to insist a neighbor whose roof drains onto your land change theirs. The article does not specify a particular gutter system, drainage method, or construction standard — it sets the result the construction must achieve, leaving the means of achieving it to the owner, so long as the outcome is that neighboring land is not made to bear water it did not have before.