DPH and DPMT: public water and coastal domains

When searching for a home, you look at the floor area, orientation and neighbourhood. You rarely ask whether the plot lies within a public-domain strip, whether an easement zone limits what you can do there, or whether the official coastline boundary runs beneath that sea-view villa.

Yet these zones exist, are officially mapped and legally protected, and have real consequences, ranging from a ban on building to part of what you thought you had bought reverting to the State.

Hogarfax checks the actual geometry of every plot against all these map layers. Below, we explain exactly what they mean.

Part I: Hydraulic Public Domain (DPH), the river's domain

What is the DPH?
The Hydraulic Public Domain (Dominio Público Hidráulico, or DPH) comprises assets belonging to the State because they form part of Spain's water system: inland waters, including rivers, streams, intermittent watercourses, lakes, reservoirs and aquifers, and the land they occupy. It includes the channels of natural continuous or intermittent watercourses, lake and lagoon beds, and surface reservoirs in public watercourses.

Put simply, a riverbed cannot be privately owned. It is public, and protective strips around it affect adjoining plots even where those plots are privately owned.

The three DPH zones you need to know

Moving inland from the edge of the channel, the law establishes three concentric zones with different rules:

1. The channel (the DPH itself)
The natural bed or channel is the land covered by water during the highest ordinary floods. It is wholly public-domain land: it cannot be built on or privatised, and any use requires an administrative concession.

2. The easement zone, the first 5 metres
This five-metre-wide public-use easement provides access for watercourse monitoring personnel. Although privately owned on paper, the land is subject to severe restrictions. It protects the ecosystem and DPH, provides access and passage for emergency vehicles, and allows boats to be moored occasionally. Building is prohibited except with exceptional authorisation.

3. The control zone, the next 100 metres
The control zone (zona de policía) is a 100-metre-wide strip on each side, measured from the boundary of the channel, in which land use and activities are regulated. Building is possible in many cases, but requires prior authorisation from the relevant River Basin Authority (Confederación Hidrográfica). Any works, earthmoving, tree planting or activity that could affect water flow requires permission. Many owners do not discover this until they submit a project and it is refused.

How Hogarfax assesses the DPH

We overlay the plot's cadastral geometry with official DPH mapping from MITECO and the river basin authorities. We calculate whether the plot lies within the channel, easement zone or control zone, and its actual distance from the DPH boundary. This is not a visual estimate: it is a precise geometric intersection that identifies even partial encroachment.

Part II: Maritime-Terrestrial Public Domain (DPMT), the coastal domain

What is the DPMT?
The coast operates in a similar way, but under its own legislation: Coastal Law 22/1988 (Ley de Costas), as amended in 2013. The DPMT defines which land belongs to the coastal public domain, guarantees public use, regulates the rational use of its assets, and seeks to maintain appropriate water and shoreline quality.

The DPMT includes the maritime-terrestrial zone, from the low-water mark to the furthest point reached by waves during the worst known storms, as well as beaches, dunes, cliffs, marshes and coastal lagoons. By definition, these areas are public and belong to the State.

The exact boundary between the DPMT and private property is established through an administrative demarcation procedure (deslinde), which produces the official demarcation line separating public and private land along the coast. The demarcation line for more than 10,000 km of Spain's coastline has been digitised so that nobody should buy a coastal home only to discover later that it falls within the DPMT and does not belong to them.

The three DPMT zones you need to know

As with the DPH, the demarcation line creates inland protection strips governed by different rules:

1. Right-of-way easement, the first 6 metres
Immediately adjoining the DPMT, this strip guarantees free public passage along the entire coast. No new buildings may be constructed within it. Existing buildings may be maintained but are classed as non-compliant with current planning rules; repairs and improvements are permitted only if they do not increase volume, height or floor area. It is the seafront-promenade strip intended to exist along the whole Spanish coast.

2. Protection easement, 100 metres (or 20 metres on urban land predating 1988)
This is the most relevant zone when buying a home. The protection easement covers privately owned land adjoining the DPMT and is subject to restrictions under the Coastal Law to protect the public domain. On non-developable land, the strip is 100 metres wide. On consolidated urban land predating 1988, it may be reduced to 20 metres. New residential buildings, removal of vegetation without authorisation and obstruction of public access are prohibited. A villa within this strip may have an irregular legal status without the buyer knowing.

3. Zone of influence, up to 500 metres
The Coastal Law defines a zone of influence extending at least 500 metres from the inland edge of the seashore. Private property is not directly restricted on the same terms here, but urban planning must take the zone into account: building density is controlled and architectural screens that distort the surroundings are prohibited.

How Hogarfax assesses the DPMT

Across Spain, we calculate the strip between the coastline and the official DPMT demarcation line published by the Directorate-General for Coastal and Marine Sustainability. From that line, we geometrically generate the right-of-way easement (6 m) and protection easement (100 m), then intersect them with the exact geometry of the cadastral plot.

The result tells you whether your plot lies within the DPMT, meaning part of what you think you are buying is actually public land, within the right-of-way easement, within the protection easement or simply in the zone of influence. It also gives the exact distance from the nearest edge of the plot to the demarcation line.

What nobody tells you when buying near the water

These zones have existed in law for decades. In practice, however, thousands of properties have been sold without buyers knowing they were acquiring land subject to severe restrictions, or even land belonging directly to the State.

The Coastal Law was specifically designed to end this situation: to ensure that nobody buys a home or other asset on the coast and later discovers that it does not belong to them because it forms part of the DPMT. But this information does not reach buyers automatically. You need to know where to look.

That is exactly what Hogarfax does.