Short answer. Yes. Article 511 of the Civil Code gives every landowner the right to build a reservoir for rainwater inside their own property. The only condition attached to that right is that the reservoir must cause no damage to the public or to third persons — get that wrong and the right stops protecting you.
What the law says
Every owner of a piece of land has the right to construct within his property, reservoirs for rain waters, provided he causes no damage to the public or to third persons.
Civil Code, Article 511 — Right To Build Rain Reservoirs. Read the full provision →
The right exists because you own the land
Article 511 states it plainly: every owner of a piece of land has the right to construct within his property, reservoirs for rain waters. You do not need a neighbor's permission to capture rain that falls on land you own — the right arises automatically from ownership, the same way you may dig a well or plant a garden. Nothing in the article ties the right to a minimum lot size, a maximum reservoir size, or a particular use for the water once collected. It is framed as broadly as the ownership itself, which is why the article sits among the general provisions on the rights of an owner rather than among special rules for specific kinds of property.
The one condition that limits it
The right is not unconditional. Article 511 requires that the owner causes no damage to the public or to third persons. A reservoir that overflows onto a neighbor's land, that undermines a shared wall, or that creates a hazard to people passing on a public street is no longer within the article's protection, whatever the owner's intention was in building it. The statute does not spell out what counts as damage or how it must be proven — that depends on the facts of each situation, including how the reservoir is built, where it sits relative to the boundary, and what actually happens to the water once it is there.
Why the location and construction matter
Because the condition is about consequences rather than intentions, the safest position is to design and site the reservoir so that seepage, overflow, or structural pressure cannot reach neighboring land or a public way. A reservoir built well inside your boundary, with water contained and controlled, is very different from one built against a property line with no barrier against runoff. The article does not require any particular engineering standard, but a reservoir that in fact causes damage exposes the owner to liability under the general rules on damage to others, separate from whatever right Article 511 otherwise gives.
What this does not settle
Article 511 addresses ownership rights over the reservoir itself; it does not by itself resolve zoning or building requirements a local government may impose, water rights questions once the collected water is used or discharged beyond the property, or disputes over an existing structure that predates the reservoir. If a dispute already exists — a neighbor complaining of water reaching their land, for example — what matters is the actual damage caused, not simply where the reservoir was built, and that is a factual question best worked through with the specific circumstances in hand.