Short answer. Article 628 of the Civil Code divides the costs in proportion to the benefit each dominant estate actually derives from the work. Anyone who does not want to contribute may exempt themselves by renouncing the easement. The servient estate's owner must also contribute if they make use of the easement themselves.
What the law says
Should there be several dominant estates, the owners of all of them shall be obliged to contribute to the expenses referred to in the preceding article, in proportion to the benefits which each may derive from the work. Any one who does not wish to contribute may exempt himself by renouncing the easement for the benefit of the others.
Civil Code, Article 628 — Several Dominant Estates Share Costs. Read the full provision →
Costs are shared in proportion to benefit, not equally
Article 628 answers the question directly: should there be several dominant estates, the owners of all of them shall be obliged to contribute to the expenses ... in proportion to the benefits which each may derive from the work. The division is not a simple equal split among however many properties benefit — it is tied to how much each dominant estate actually gains from the easement's upkeep. A property that relies on the easement heavily contributes proportionally more than one that benefits only marginally.
Any owner can opt out by giving up the easement
The article also gives an exit: any one who does not wish to contribute may exempt himself by renouncing the easement for the benefit of the others. An owner is not locked into paying a share indefinitely simply because their estate is technically a dominant estate. Renouncing the easement removes both the obligation to pay and, necessarily, the benefit the easement was providing — the article frames this as a genuine trade-off rather than a way to keep the benefit while dropping the cost.
The servient estate's owner is not automatically excused
Article 628 extends the contribution obligation beyond the dominant estates: if the owner of the servient estate should make use of the easement in any manner whatsoever, he shall also be obliged to contribute to the expenses in the proportion stated, saving an agreement to the contrary. So the owner of the land that carries the burden of the easement is not exempt from sharing costs if that owner also uses the easement — using it triggers the same proportional contribution duty, unless the parties have agreed otherwise.
What this means for working out each share
Because the split depends on actual benefit rather than a fixed formula, resolving a dispute over easement maintenance costs among several beneficiaries requires looking at how each property genuinely uses and benefits from the easement — not simply counting how many estates are connected to it. Where an owner disputes their assessed share, the article's proportional standard, and the renunciation option it offers as an alternative to paying, are both directly relevant starting points.