Is my plot in a flood zone in Spain? How to check the SNCZI map

How to check a property on Spain's SNCZI flood map

MITECO's Sistema Nacional de Cartografía de Zonas Inundables (SNCZI) covers only the river stretches that have been studied. Neither an unshaded plot nor an agent's assurance that it has never flooded proves that the property is safe. Check the map yourself, then ask the town hall and the neighbours.

Open the SNCZI viewer on a computer (on a phone, the infoAGUA app is an alternative). Its buttons are icons; point at one to see its name. To find the plot, click Herramientas (the spanner, bottom right), then Localizar, choose Referencia catastral and type the plot's cadastral reference. The viewer drops a pin but does not draw the boundaries: compare the pin and the house with the property plan, and if they lie close to a flood line, ask a surveyor or architect to check.

1. Click Árbol de servicios (the folder, top left), then Cartografía de zonas inundables (ZI) de origen fluvial and Extensión de zonas inundables. Click a layer name to switch it on, and again to switch it off: T=10, T=100 and T=500 años, one at a time, because the 500-year layer hides the others. Leyenda (the speech bubble) shows each colour.
2. For water depth (calado), switch on Peligrosidad por inundación fluvial T=100 años under Mapas de peligrosidad in the same folder (RD 903/2010, article 8.3.a). Leyenda shows depth bands from under 0.2 m to over 2 m; when we tested it, clicking a point returned no figure, so read the colour. Check it where the house and its access road stand: more than 1 m in the 100-year flood is one of the tests for the preferential flow zone (ZFP), where specific building restrictions apply. Ask a surveyor or architect (técnico) to compare the predicted flood level with the floor levels of the bedrooms and living rooms and with the level of the access road.
3. Under Cauces con estudios de dominio público hidráulico (DPH), switch on Zona de flujo preferente (the ZFP) and the riverbed lines: Cauces con DPH cartográfico (estimated) or Cauces con DPH deslindado (approved). There is no layer for the 5 m easement (servidumbre) or the 100 m control zone (zona de policía); measure them from the line with Herramientas > Mediciones and ask the basin authority to confirm that the usual widths apply. The estimated line is only a guide; an approved deslinde is binding, and the 5 m and 100 m strips are measured from it. If no deslinde is approved or the house is close to the line, ask the basin authority to confirm where the boundary runs.
4. Mark the house and proposed works against each boundary: a plot can straddle the control zone.
5. Save the map, study name, approval date and organismo de cuenca (basin authority). Maps are reviewed every six years: ask whether a newer cycle exists before paying (RD 903/2010, article 21.2). In the Valencian Community, also ask how the regional flood plan, PATRICOVA (Decree 201/2015), classes the plot: it has its own hazard map.

Which basin authority you write to depends on the river basin. For example:

• Most of Murcia and the south of Alicante (Vega Baja): Confederación Hidrográfica del Segura.
• Most of the rest of the Valencian Community: Confederación Hidrográfica del Júcar.
• Andalusia: Confederación Hidrográfica del Guadalquivir in its basin; Junta de Andalucía in the Andalusian Mediterranean basins (from the Campo de Gibraltar to Almería), Guadalete-Barbate and Tinto-Odiel-Piedras; a few areas drain to the Segura or the Guadiana.
• Catalonia: Agència Catalana de l'Aigua (ACA) for Catalonia's internal basins; Confederación Hidrográfica del Ebro for the Ebro basin (most of Lleida).

Submit your enquiry through its sede electrónica (online portal) or at an official registro (document submission office): give the referencia catastral, attach a site plan and a short description of the works, and ask for a written reply.

These layers do not show surface-water flooding or local drainage: ask your surveyor or architect to check both.

No works planned? Go straight to home insurance and the checks before paying a deposit; near the sea, also read the coast section.

What do the T10, T100 and T500 return periods mean?

A return period of T years means a 1-in-T chance each year of a flood exceeding that level: T10 is 10% a year, T100 1% and T500 0.2%. T100 does not mean one flood every hundred years: the chance of at least one such flood in 30 years is roughly 26%; for T10, 96%; for T500, 6%.

The legal zona inundable, or flood zone, is the land the theoretical 500-year flood would reach (article 14.1 of the Public Water Domain Regulations, the RDPH).

Which restrictions apply near a river?

These are the national rules. Regional governments may add complementary rules, so ask the town hall and the basin authority which ones apply to this property.

Easement and control zones: measure from the watercourse boundary

The watercourse boundary is set by the highest ordinary floods. A channel carrying only occasional rainwater is private if it crosses only private land from its source. Even then, the owner may not build anything that changes the water's course to others' harm or that could cause damage if a flood destroyed it (Water Law, article 5). If a dry channel crosses the plot, check its status.

The control zone restricts building work, major changes to ground levels, aggregate extraction and activities that obstruct floodwater or harm water quality.

Can you build or extend in a preferential flow zone in Spain?

The ZFP is where a 100-year flood would cause serious damage (water depth above 1 m, velocity above 1 m/s, or depth multiplied by velocity above 0.5 m²/s), plus the main discharge corridor, the vía de intenso desagüe. Land in either area is ZFP (RDPH, article 9.2). The rules depend on the land's status on 30 December 2016, when they took effect.

If you plan to extend the house:

• ZFP on land that was rural on 30.12.2016: generally no.
• ZFP on land already urbanised by then: possible with safety conditions and a Registry certificate.
• T500 outside ZFP: it depends on the land status, the town plan and the safety conditions; putting new rooms above the 500-year flood level does not guarantee permission. Ask the town hall and the basin authority in writing whether your extension is treated as a new building, because that decides which conditions apply.
• Within the 100 m control zone: also ask the basin authority what approval or notification your works require.

These can apply together: if you plan to extend a house 60 m from the watercourse boundary, in T500 but outside the ZFP and on rural land, confirm which article 14 bis conditions apply (see below) and what the control zone requires.

ZFP on land that was rural on 30 December 2016

For an extension: generally prohibited. Article 9 bis.1 lists the banned works; for a house, these matter most:

• A new house or repairs and renovation increasing footprint or volume, including an extension.
• Changes of use that increase vulnerability to flooding.
• Underground garages, basements, any below-ground building and permanent surface car parks.
• Impermeable enclosures and fences, such as watertight walls.
• Raising ground levels with fill that significantly reduces discharge capacity.

Repairs and renovation that add no footprint or volume are not on this list, and works essential to adapt existing buildings to sector-specific regulations are excepted. If the purchase depends on an extension, assume it is not possible here unless the basin authority confirms in writing that an exception below or a municipal 9 quater regime applies.

Pool, rebuild or garage? Ask the basin authority how it classes your project, for example whether demolishing and rebuilding counts as a new building. For an in-ground pool, ask whether it counts as below-ground construction. This ban applies only in ZFP on land that was rural in 2016. In ZFP on urbanised land, ask whether the pool falls under the article 9 ter conditions; elsewhere within 100 m of the watercourse boundary, ask what the control zone requires. In T500 outside the ZFP and the control zone, ask the town hall whether the article 14 bis conditions apply to it.

There are also narrow exceptions: farm buildings of up to 40 m², works for recognised water uses, and the conservation, adaptation and restoration of construcciones singulares (buildings of particular significance) keeping their traditional use or one authorised before 30 December 2016 (a museum is the only change allowed). None allows a new home. All three must not make people or property more vulnerable, significantly worsen flooding or hamper urban flood defences.

Suelo rural is a national land status: land protected from development, or land where development works are not finished. It differs from the municipal suelo rústico classification. Land counts as urbanised only if it is legally part of the town's urban fabric (malla urbana) and also meets one of the Land Law's tests: developed under the plan, infrastructure and services in place, or a minimum share of plots already built on; some traditional rural settlements also qualify. A road along the plot is not enough. Ask the town hall to confirm the plot's status on that date in writing and identify the supporting documents.

ZFP on land already urbanised on that date

For an extension: possible with conditions. Article 9 ter allows new buildings, extensions, changes of use and basements if they do not increase vulnerability, significantly worsen flooding or constrain urban flood defences. The conditions:

• New residential uses at a height the 500-year flood would not reach.
• Underground garages and basements watertight for that flood, with structural studies against collapse that account for debris and sediment carried by floodwater, and vents and escape routes above that level.
• Before works, a Land Registry certificate confirming an entry that the building is in ZFP.

Special municipal regime under article 9 quater

New buildings only outside the control zone. Article 9 quater provides a special regime for municipalities with at least a third of their area in ZFP, or where terrain and other constraints prevent building outside flood zones. The regional government must recognise it; until then, each application needs its own technical justification accepted by the competent authorities. Ask the town hall whether the town has been recognised.

Even where the town has this recognition, new buildings under it must stand outside the 100 m control zone, meet the safety conditions and have the Registry certificate before work starts. If your house is within 100 m of the watercourse boundary and the extension is treated as a new building, this regime will not help.

What building restrictions apply elsewhere in the T500 flood zone?

For an extension: possible with conditions, not guaranteed. Outside the ZFP, article 14 bis distinguishes the land's status on 30.12.2016:

• Rural land: new activities and buildings must, where possible, be sited outside the flood zone. Otherwise, regional rules apply, taking account of article 14 bis.1.a: new homes above the 500-year flood level, specific conditions for basements, and emergency access.
• Sensitive uses such as hospitals, schools, care homes and campsites should be avoided on that rural land; a private house is not one of them.
• Already urbanised land: new buildings may be permitted, applying the safety conditions and sensitive-use limits above as far as possible.

In the control zone, works generally need prior authorisation or a declaración responsable (RDPH, article 78 ter.1); ask the basin authority to confirm the procedure. Outside this zone, the competent authority grants permission subject to these rules, with a prior basin-authority report unless the plan already includes it (RDPH, article 14 bis.5).

The Land Registry certificate required before works confirms the flood-zone entry under article 14 bis.4 or, in the case covered by article 9 ter.2, the ZFP entry. Building work begun before 30 December 2016 did not need that entry under this rule; check later works separately. A missing entry does not mean the property is free of flood risk.

In Andalusia, the regional planning law (LISTA) sets no time limit for action against unlawful works on rustic land preserved for flood risk while that risk lasts: for a house without a licence on rustic land, age alone does not protect it.

What if the property is near the coast?

Check sea flooding as well. Where coastal defences are considered adequate, the marine map may show only the low-probability scenario, T500, so an empty high-probability layer does not prove the plot is free of marine flood risk. In the same SNCZI viewer, open Árbol de servicios > Cartografía de zonas inundables (ZI) de origen marino. Check the deslinde de Costas, the coastal boundary, too; it falls under a separate legal regime.

What does the TerrenoCheck report check?

Home insurance and the Consorcio: what should you check?

The Consorcio de Compensación de Seguros, a state-backed insurer, pays for damage from extraordinary events such as floods, if your own policy meets its conditions. To claim, you need a policy with premiums paid up that covers at least one ordinary risk, such as fire or theft; a standard home insurance policy does. No excess applies to homes or to a building's owners' association (comunidad de propietarios). The Consorcio covers the same property and the same sums insured as your policy (RD 300/2004, article 5.1): if you insure only the contents, the building is not covered, and underinsurance can reduce the payout: confirm how the proportional rule applies (article 5.3). In a flat, the building may be insured by the owners' association: ask for that policy too. Damage from rain falling directly on the house, or collected by its roof, terrace, drains or patios, is not an extraordinary flood (RD 300/2004, article 2.1.c): ask the insurer how your ordinary policy covers it.

A new policy normally has a seven-day waiting period for extraordinary-risk cover. It does not apply when the policy replaces another without a gap (except for any increase in the sum insured or new cover), or when you can show you could not insure earlier because you had no insurable interest (RD 300/2004, article 8.1). Arrange buildings and contents insurance from completion, with sums insured calculated on the policy's valuation basis, and get written confirmation of when extraordinary flood cover starts.

What must be resolved before paying a property deposit?

If you plan works, or the house had works after 2016, ask the town hall to confirm in writing the plot's land status on 30.12.2016 and the rules for those works. Attach the plan and a description of the works; check the answer with the basin authority.

Do not pay the deposit yet if…

• The extension your purchase depends on is prohibited, or nobody has established which regime applies.
• Doubt about the watercourse, map coverage or the position of the house could change what you can do with the property.
• Required authorisations or certificates have not been verified, and the relevant authority has not confirmed in writing that they were not needed.
• Bedrooms, living rooms or the only access road have flooded, or lie within the 10- or 100-year flood extent, and you have not worked out what that means for safety and repairs.
• No insurer will quote affordable cover.
• The agreement binds you to buy even if outstanding checks contradict what you were offered.

A refund is not automatic. Ask your lawyer which type of arras the contract uses: with arras penitenciales you can withdraw by losing the deposit, and the seller by repaying double (Civil Code, art. 1454); other types can bind you to complete. Ask the same in writing about any reservation payment (reserva) the agent requests: whether and when it is refunded. Notarial checks do not replace a review of flood risk and permissions by your lawyer and surveyor or architect.