Flood prone land: how to find out before buying and what to do if you already own it

By Rodrigo Parada Aranda and Julián Aranda

How to check whether land floods before buying? Step by step

The recent storm affecting various parts of the country has reminded us how vital geography is when choosing where to live. Far from dramatising, this context invites us to be responsible investors. Flood risk is public information that can and should be known before you part with your savings. The undisputed protagonist at this research stage is the Prior Information Certificate (CIP).

The CIP is an official document issued by the Municipal Works Department (DOM) containing the planning identity of an urban plot. It states the zone it falls within, what may be built there and, most importantly for us today, whether the plot sits in a risk area. It is an inexpensive document and easy to obtain; in fact you can request it through the official DOM digital portal or directly at the relevant municipality by providing the assessment roll number. Our legal advice here is categorical: if you are going to sign a promise of sale, always make the purchase conditional on the CIP not showing insurmountable restriction areas and on a favourable outcome of our professional title study.

What does it legally mean that the land is in a risk area?

If the CIP indicates that the property is in a risk area, that does not mean the sale is unlawful or prohibited. Article 2.1.17 of the General Ordinance on Urban Planning and Construction (OGUC) regulates precisely this situation within territorial planning instruments. In simple terms, that article provides that in order to build in such zones a reasoned risk study prepared by a specialist professional must be submitted, defining the necessary mitigation works.

Those works, such as special retaining walls, raising foundations above the flood level, or perimeter drainage systems, must be approved by the competent body and fully completed before the dwelling receives its final approval. This translates into very clear practical effects for the buyer: building permits will be conditional, construction costs will inevitably be higher because of the mitigation works required, and higher insurance premiums or flood exclusions are likely. The future resale value may also be affected by the area's reputation. Approaching the purchase knowing these rules will allow you to negotiate the price with the seller fairly and realistically.

The case of rural land without a zoning plan

The greatest challenge lies in rural areas. Here flood risk is generally not mapped by traditional planning rules. Beyond urban boundaries the CIP loses part of its predictive power regarding specific hazards. In that rural setting, empirical factors take over: the history of flooding in the area, proximity to streams, dry ravines and natural watercourses, the particular topography of the land, and the valuable local memory of longstanding neighbours.

The architect's expert view strongly recommends that, faced with a rural property, the correct and decisive tool is a rigorous topographic survey including a runoff profile. Through our surveying and architectureservice, this technical study makes it possible to understand where rainwater naturally drains, identify hollows where water pools, and design the exact position of the dwelling at the safest level, raising it if necessary to prevent contact with seasonal flooding.

What options do you have if you already own land in a flood prone area?

If you have already bought the property and have recently learned that it lies in a risk area, staying calm and acting in a logical order is essential. These are your five real options:

1. Get accurate information: Request an up to date CIP if you are in an urban area, or a topographic survey if you are rural, in order to understand the technical scale of the risk and not act on rumour.
2. Mitigate the physical risk: Design and carry out retaining and functional landscaping works. Maintain your own and adjoining watercourses and channels rigorously. Sometimes clearing gutters and drainage ditches makes the difference.
3. Insure the property: Review the cover in your home insurance policy in detail. Many general policies exclude damage from exceptional natural events or river flooding unless additional clauses are contracted.
4. Regularise what has been built: A dwelling without final approval that suffers damage faces serious problems accessing State aid or claiming on insurance. Regularise the construction through the correct routes, such as the Ley del Mono.
5. Sell with complete transparency: If you decide to sell, you have a legal and moral duty to be transparent with the buyer about the history of flooding. The Chilean Civil Code is strict about hidden defects; concealing this information entitles the buyer to rescind the contract or demand a drastic price reduction, and even compensation for loss.

Rebuilding after the storm: legal routes and the megareform

For families who have unfortunately suffered material damage during the storms, the question is how to get back on their feet. There are two broad paths: rebuilding with a municipal permit from the outset, submitting mitigation projects, or the frequent option of rebuilding quickly to restore a roof over your head and then regularising what has been built using exceptional rules. On this second route you can read in detail in our article on how to obtain final approval through the Ley del Mono in Chile.

At a macro level the State has proposed relief measures. Within the recent economic and housing megareform, provision is made for building and financing homes for families affected by catastrophic events, especially in the Ñuble and Biobío regions, where the storm fronts left deep scars. This project seeks to inject momentum into reconstruction and, although its details are still being debated in Congress, it relates directly to the recovery initiatives we analysed in our recent article on zero VAT on new homes and how the megareform works.

To understand the full liability framework, we suggest reviewing the first articles in this series: our legal guide for those whose homes have flooded and our in depth analysis of who is liable for flood damage.

Checklist: risk verification before buying

Frequently asked questions

Tell us your situation and we will tell you what applies.