How to check a water letter is real before you buy land in Costa Rica

To check that a water letter is real, contact the issuer yourself, using contact details you find independently, and ask it to confirm in writing that it issued that letter, for that exact lot, and that it is still valid. Then check the letter against the Registro Nacional records for the property and confirm the ASADA or provider is legally constituted and still authorised by AyA to run the local water system. Do all of this before any deposit leaves your account.

This guide covers what a genuine water letter should contain, how to confirm it directly with AyA, an ASADA or a municipality, how to match it to the lot, how to check expiry and conditions, how to check a well or spring concession, the warning signs of a forgery, and what to do if the letter turns out to be fake.

This guide is general information, not legal advice. Use a Costa Rican lawyer who represents only you for any purchase.

Why this guide exists

Someone came to us after paying a reservation deposit on a property that had no water letter. The seller had forged one. Our main guide on the water letter in Costa Rica explains what the letter is and how to request one. This guide covers a different question: the letter someone shows you, and whether you can trust it.

The stakes are high. Without a valid letter the municipality will not issue a construction permit, and roughly one in four development projects that request a water availability determination is now turned down (Tico Times, August 2026). The Contraloría reported that ASADAs rejected 50.05% of new service requests in 2025, up from 41.41% in 2024 (Delfino, August 2026). A real letter has value, which is exactly why a fake one gets made. For other tricks to watch for, see our guide to common real estate scams in Costa Rica.

What does a genuine water letter contain?

Formats vary between AyA, each ASADA and each municipal aqueduct, so there is no single template to compare against. What the regulations do tell you is what the letter is supposed to say and what it is based on.

• An issuer that runs the system. Under ARESEP's regulation for water and sewer services (AR-PSAYA-2013), the service provider issues the availability opinion (dictamen de disponibilidad) for a new connection, and it must be based on an availability study.
• The specific property. AyA's service regulation (La Gaceta, April 2015) asks the applicant to state the finca and cadastral plan (plano catastrado) numbers and to supply a certified copy of the plano and the registered owner's ID. A letter that does not identify the lot by these numbers proves little.
• The project. The same AyA application states the nature and purpose of the project, so the letter should match what you plan to build, for example one house or several units.
• Conditions and works. ARESEP's regulation says the opinion must state any works the applicant has to finance and build to connect.
• A date. Validity runs from the date of issue (see below), so an undated letter cannot be checked.

We could not find an official public standard for signatures, seals or reference numbers that applies to every provider. Treat those as things to check with the issuer, not things you can judge by eye.

Also check what kind of document it is. A constancia de capacidad hídrica is not an availability letter. Under AyA's service regulation (2015), the operator issues it when it denies availability but the system could serve the lot once the applicant builds the required infrastructure. Municipalities do not accept it for a building permit.

How to verify a water letter with the ASADA or AyA

The single most useful check is to ask the issuer directly. A forger can put any phone number or email on a letter, so do not use the contact details printed on it.

1. Identify the provider from independent sources. Find out which entity runs the water system where the lot sits: AyA, an ASADA or a municipality. Ask the municipality, neighbours or your own lawyer, and get AyA's contact details from its official website, aya.go.cr. ECIJA advises confirming contact details yourself and avoiding unofficial links sent through social media or messaging apps (ECIJA, May 2026).
2. Send a copy of the letter and ask three questions in writing. Did you issue this letter? Does it relate to this finca and plano number? Is it still valid, and has anything changed since it was issued?
3. Ask for the answer in writing, on the provider's letterhead or from its official email address, signed by someone with authority to sign.
4. Ask whether the system is accepting new connections now. The Tico Times recommends confirming which entity issued the letter and whether that system is currently accepting new connections.

Check that the ASADA is legally constituted and recognised by AyA

An ASADA is an organisation legally constituted to provide water services that holds a delegation agreement (convenio de delegación) from AyA; the aqueduct belongs to AyA and its administration is delegated (ARESEP, AR-PSAYA-2013). Two checks follow from that:

• Legal existence. ASADAs must be associations constituted and registered under the Associations Law (Ley 218) (ASADA regulation, Decreto 32529-S-MINAE). The Registro Nacional sells a personería jurídica certification online that shows who holds legal representation of a registered entity (Registro Nacional services guide, 2025). Ask your lawyer to check the ASADA's registration and compare the names with whoever signed the letter.
• Current delegation from AyA. We could not find a public online list of ASADAs with active delegation agreements, so ask AyA in writing whether the ASADA named on the letter currently holds a delegation agreement and is authorised to issue availability letters. Delegations can change: in May 2026 AyA's board revoked the delegation of the Sonafluca ASADA in La Fortuna de San Carlos and took over the service directly (Delfino, May 2026), and in 2021 AyA determined that at least 30 ASADAs in Nicoya did not meet minimum technical requirements and could not grant availability letters for new construction (Voz de Guanacaste, April 2021).

Check the letter matches the exact lot

A genuine letter for the lot next door, or for the mother parcel before it was split, is still the wrong letter. Compare these against the Registro Nacional records and the plano catastrado:

The Tico Times recommends pulling the Registro Nacional folio real and having a licensed surveyor check the plano against the physical boundaries. If the details do not match, ask the issuer which property the letter actually covers. Our guide to buying land in Costa Rica to build covers the rest of the land checks.

How long is a water letter valid, and what conditions apply?

A letter can be genuine and still useless because it has expired or no longer fits the project.

• AyA letters: 12 months, extendable on request before expiry for up to two further periods of the same length, if the applicant shows it has been moving the project forward and the project and availability conditions have not changed (AyA service regulation, 2015). Extensions are not automatic.
• ARESEP rule for providers: an availability opinion lasts at least 12 months from issue and can be extended once, for up to the same period (ARESEP, AR-PSAYA-2013).
• Changes void it: under AyA's regulation, a change to the use or to the conditions in the availability document voids it, after due process.
• ASADA practice: a positive determination generally holds for about twelve months, and if construction has not started the water board can require a new inspection, possibly under tighter conditions (Tico Times, August 2026).

Rules can differ between providers and change over time, so ask the issuer to state in its written confirmation the expiry date, whether an extension is possible and any conditions, such as works you must pay for.

Wells and spring concessions

If the seller says the water comes from a well or spring rather than a provider, the paper to check is different. Groundwater is national property. A well for domestic use on the same property does not need a concession but must be registered; development, condominium or rental use needs a full concession from MINAE's Dirección de Agua (Tico Times, August 2026).

• Ask for the concession or well registration number and the file (expediente) number.
• Confirm with the Dirección de Agua that it exists, is current, is registered to the seller and covers your intended use. A residential concession does not cover a hotel (Tico Times).
• The Dirección de Agua handles concessions, transfers and renewals through its online procedures platform, which requires a login (Dirección de Agua user manual, 2019). We could not find a public search tool, so have your lawyer request confirmation from the Dirección de Agua directly.

Red flags of a fake water letter

• The seller will only send a photo or a scan and will not let you contact the issuer.
• The contact details on the letter differ from those you found independently.
• No finca or plano number, or numbers that do not match the title record.
• No date, or a date that makes it look valid for longer than the rules allow.
• The issuer named does not run the water system in that area, or the ASADA has no registered legal existence.
• The letter is in an owner's name that does not appear in the property history.
• Pressure to pay the reservation deposit before you can check anything. On water questions, the Tico Times advises that if the answer is a shrug, you should treat that as the finding.
• A capacity letter presented as an availability letter.

None of these proves forgery on its own. Each one is a reason to stop and verify with the issuer.

What to do if the water letter is fake

1. Stop all payments. Do not send any further money, and ask your bank whether a recent transfer can still be stopped.
2. Keep everything. Save the letter, messages, emails, the reservation agreement and payment records. ECIJA notes that contracts, receipts and written communications can protect you later.
3. Get the issuer's statement in writing that it did not issue the letter.
4. Talk to your own lawyer about recovering the deposit and about filing a criminal complaint (denuncia) with the OIJ, the judicial investigation police. The OIJ also has a free confidential line for information, 800-8000-645 (Teletica, June 2026).

Recovery can be slow. If a deposit is paid directly to the seller and they refuse to return it, you would have to sue, which CostaRicaLaw.com calls time consuming and costly.

Make the deposit conditional on water letter verification

The strongest protection is in the reservation or purchase agreement itself. Whether a deposit is refundable depends on the contingency or due diligence conditions written into the agreement, and CostaRicaLaw.com recommends an approved escrow company to hold it rather than paying the seller directly. The Tico Times recommends a SUGEF-registered escrow agent, an attorney who represents the buyer alone, and a letter that is in hand, current and in the buyer's favour before money moves.

As general points to raise with your lawyer:

• Make the deposit refundable if the issuer does not confirm the letter in writing within an agreed period.
• Name the finca and plano numbers and the planned use the letter must cover.
• Hold the deposit in escrow, not with the seller or the seller's agent.
• Do the same for any well or spring concession.

Once the water is confirmed, our permits and water letters page explains how it fits into your permit file.

How Decentra Homes can help

Decentra Homes is an award-winning custom home builder in Costa Rica, founded in 2020, with 50+ residential and commercial projects. If you are weighing a lot, you can book land and construction consulting with a CFIA-licensed engineer and architect with 15 years of experience, at $200 per hour, and bring the listing, the plano catastrado and the water letter you have been shown before you pay a deposit. This works alongside your own lawyer's checks, not in place of them. For new builds: Minimum construction budget $350,000 USD, before land. Message us on WhatsApp or through our contact page.