Short answer. The landowner whose fault caused the damage bears the entire cost of repair works, not just a proportionate share. Article 517 of the Civil Code distinguishes between owners who simply benefit from water works — who share costs proportionally — and those whose fault caused the damage, who are fully liable for the expenses.
What the law says
Those who by their fault may have caused the damage shall be liable for the expenses.
Civil Code, Article 517 — Sharing The Cost Of Works. Read the full provision →
Two distinct rules in one article
Article 517 contains two separate rules that apply to different situations. The first rule covers owners who benefit from water works — they must contribute to construction costs in proportion to their respective interests in the works. The second rule applies when there is fault involved: owners whose negligence or wrongdoing caused the damage bear the full cost of repair. These are not alternative rules — they address different scenarios. Fault is the dividing line.
What 'fault' means in this context
Fault under Article 517 refers to negligent acts or omissions by a landowner that caused a waterway to overflow or otherwise damage neighboring properties. This could include failing to maintain a dike, blocking natural drainage, or improperly altering the flow of a river in a way that was foreseeable to cause harm. The landowner at fault is not merely asked to contribute proportionally — they are made liable for the expenses as a consequence of their wrongful conduct, not simply their interest in the land.
Practical consequences for the at-fault landowner
If your neighbor's negligence caused a river to flood and damage your property and others', that neighbor does not get to split the repair bill with everyone else. The law makes them answer for the full cost. This means you may be entitled to claim the cost of repair works directly from the at-fault owner rather than absorbing your share quietly. The remedy depends on proving fault — establishing what the neighbor did or failed to do, and connecting that conduct to the overflow that caused the damage.
When costs are shared without fault
It is worth noting that Article 517 also speaks to the ordinary case where water works benefit multiple owners without anyone being at fault. In that situation, contributing owners share costs in proportion to their respective interests. This proportional-sharing rule is the background rule; the fault rule overrides it when negligence enters the picture. Understanding both rules helps you assess your position: if there was no negligence and you simply benefit from the works, your contribution is limited to your proportional share.