Your neighbor's excavation or drainage damaged your plot: Thailand's law of neighboring properties

Can you sue a neighbor whose construction damages your Koh Phangan land, even if their building permit is in order? Yes — Sections 1337 to 1348 of the Civil and Commercial Code (CCC) set out a distinct body of private civil law governing disputes between adjoining landowners: nuisance, water drainage, excavation safety, and shared boundary walls and trees. A permit being correctly issued doesn't excuse a builder from these rules, and a neighbor doesn't need to prove a permit violation to bring a claim under them.

The general nuisance rule (Section 1337)

Section 1337 is Thailand's closest equivalent to a nuisance doctrine: if a person's exercise of their own property rights causes an adjoining owner 'greater injury or inconvenience than should naturally and reasonably be expected' given the nature and location of the land, the affected owner can seek an order to stop the interference (abatement) plus compensation for the damage already done. This is the general catch-all a Phangan neighbor would reach for when construction activity — noise, dust, vibration, or the more concrete problems below — crosses the line from ordinary building disturbance into unreasonable harm.

Water and drainage (Sections 1339-1341)

• Natural water flow must be accepted. A lower plot must accept water that flows naturally from higher land; the upper landowner may only retain the water genuinely needed for their own property, not dam or hoard it to the lower owner's detriment.
• Artificially redirected drainage creates liability. If an upper landowner channels water artificially — a graded driveway, a concrete apron, a French drain — onto a lower neighbor's land and it causes damage, the lower owner can require the water be redirected to a public watercourse at the upper owner's expense.
• Roofs can't be built to dump rainwater on a neighbor. Section 1341 specifically bars constructing a roof or other structure so that rainwater falls onto the adjoining property — a common problem on Phangan's tightly built village lots where a new second story overhangs the boundary.

Excavation and soil stability (Sections 1342-1343)

• A 2-metre setback for wells, ponds and cesspools. No well, pond, cesspool or similar waste receptacle may be dug within 2 metres of a boundary line.
• A depth-based setback for other excavation. Trenches, foundations and buried pipework must keep back from the boundary by at least half the excavation's depth, with a 1-metre minimum regardless of how shallow the dig is.
• Excavation that endangers a neighbor's land needs protective works. Section 1343 requires anyone excavating or loading their land in a way that could destabilise the adjoining soil to take adequate protective measures — think retaining walls and shoring on Phangan's hillside cut-and-fill builds, exactly the kind of construction the island's Samui Model hillside enforcement sweep targets from the public-law side. Section 1343 is the private-law mirror of that same risk: even a fully permitted excavation can trigger a neighbor's civil claim if it isn't shored properly.

Boundary walls, fences and trees (Sections 1344-1348)

• A wall, fence, hedge or ditch sitting on the boundary line is presumed jointly owned by both adjoining owners, with shared maintenance obligations, unless the title or a survey marker shows otherwise.
• Either owner can partition a shared hedge or ditch by building their own wall or fence along the boundary at their own expense.
• A tree standing on the boundary line is presumed jointly owned, and its fruit and timber are divided equally between the two neighbors.
• Roots that cross the boundary can be cut and kept by the receiving landowner at any time; overhanging branches can be cut and kept too, but only after giving the tree owner notice to remove them first.
• Fruit that falls naturally onto a neighbor's land belongs to that land — it isn't the tree owner's to reclaim.

How this differs from what else is on this site

This is a distinct layer from several other guides here. Landlocked land and the way of necessity is about a right of access across a neighbor's land, not liability for nuisance or drainage. Section 69 bis boundary re-survey is an administrative Land Department procedure for correcting where a title's recorded boundary sits — it doesn't touch what one neighbor owes another once the boundary is settled. And hillside slope building limits are public zoning caps enforced by the state; Sections 1337-1343 are a private right a neighbor holds regardless of whether the local authority ever gets involved.

The practical takeaway for anyone building near a boundary on Phangan: a signed-off permit protects you from the state, not from your neighbor. Before excavating, grading a driveway, or designing a roofline near a property line, check these setbacks and drainage rules — and if you're the one affected, know that a valid permit on the other side doesn't defeat your claim under Section 1337.