Building a house in Costa Rica: the water and wastewater permits

Building a home in Costa Rica involves more offices than most people expect, and the paperwork is in Spanish. The good news is that, for a single-family house, the water and wastewater part follows a clear logic: prove you have water, prove the lot can treat its wastewater, and put both in the construction plans. Once that is done, the municipality can issue the building permit.

This guide covers that path for a typical house. If you are planning a hotel, a condo or any project with a treatment plant, the permits are different and heavier; see our guide to wastewater permits in Costa Rica. Everything here is general information based on the regulations in force in November 2026. Each lot and municipality has its own details.

Who is who

A short glossary before the steps:

• Municipality (municipalidad): the local government of each canton. It issues the land use certificate and the building permit, and applies its zoning plan if it has one.
• AyA: the Costa Rican Institute of Aqueducts and Sewers, the national water and sewer utility.
• ASADA: a community water association that runs the local water system in many rural and coastal towns, under AyA oversight.
• CFIA: the Federated Association of Engineers and Architects. Every construction project needs a registered professional.
• APC: the CFIA's online platform where plans are uploaded and reviewed.
• Ministry of Health (Ministerio de Salud): reviews sanitary aspects, including wastewater.
• MINAE: the Ministry of Environment and Energy. Its Water Directorate handles wells, water concessions and discharge permits.
• SETENA: the National Environmental Technical Secretariat, which grants environmental approval when a project requires it.

Step 1: the land use certificate

Start at the municipality with the lot's registered survey plan (plano catastrado). The land use certificate (certificado de uso de suelo) tells you whether a home is allowed on that lot and under which conditions: coverage, height, setbacks and density, when the canton has a zoning plan.

On the beach there is an extra layer. Under Law 6043, the first 200 meters from the ordinary high-tide line are the maritime zone: the first 50 meters are public and cannot be built on, and the remaining 150 meters are a restricted zone where land is held under municipal concession, not ownership. If your lot is in that strip, its rules come before anything else.

Step 2: the water availability letter

The project must show it has drinking water. The document is the water availability letter (carta or constancia de disponibilidad de agua), issued by whoever runs the water system at that spot: AyA, a local ASADA or, in some cantons, the municipality itself.

The operator checks two things: that there is a pipe in front of the property and that there is enough water. When either is missing, the answer can be negative or conditioned on works. In that case the alternatives are a well or another source with the corresponding permit. Our guides on buying land and on water well permits explain those routes.

The same letter also tells you whether there is a sanitary sewer you can connect to. In most beach towns there is none, so the house will treat its own wastewater on the lot.

Step 3: the percolation test and septic design

Without a sewer, a house normally uses a septic tank or improved septic tank with a drain field. Decree 42075-S-MINAE sets what must be presented when the drinking-water use is up to 190 m³ a month, which covers almost every home:

1. A septic tank or another system approved by the Ministry of Health, meeting the minimum design rules in Annex 1.
2. A drain field designed according to Article 11: plan view with the exact coordinates of the tests, longitudinal and cross sections, and construction details.
3. The calculation report for the drain field, with the estimated monthly water use, and the registered survey plan showing the tank and field on the site.
4. The percolation test report, done as Annex 3 describes: at least two tests, after 24 hours of soaking.

Article 7 says items 2 to 4 are submitted inside the construction project, under the national plan-review regulation (Decree 36550). In other words, the septic design is not a separate permit for a typical home: it is part of the plans, and if it is weak the plans come back with corrections.

Two site rules can change the architecture, so check them early: trenches are not allowed on slopes over 30 %, and the water table must be at least 1.5 m below the trench bottom. On a steep ocean-view lot or a flat lot near an estuary, the drain field may decide where the house sits. See how a septic system is sized and our percolation test service.

Step 4: CFIA plans through APC

Your engineer or architect, registered with the CFIA, prepares the full set of plans: architecture, structure, electrical, plumbing and the sanitary system. The project is registered and uploaded through APC, where the institutions involved review it. The CFIA's public requirements site, Trámites Construcción, lists what each type of project must include.

Decree 42075 adds a practical detail: all documents must be in Spanish and in metric units. Your professional takes care of that, but it is one reason a foreign design has to be adapted locally.

Step 5: the municipal building permit

With the plans approved in APC, the municipality reviews its own requirements and issues the building permit (licencia or permiso de construcción), charging the fee its rules set. Only then can work start. During construction, the professional in charge supervises the work, including the tank and the trenches.

When a house needs more

Some homes go beyond this basic path:

• Large or multi-unit properties. If projected water use goes over 190 m³ a month, as with several villas sharing one system, the wastewater must go through a treatment system approved under Decree 39887-S-MINAE, with a Ministry of Health location permit and operational reports.
• Discharge instead of infiltration. If the soil, slope or water table rules out a drain field and the treated water must go to a creek, the project needs a discharge permit from MINAE's Water Directorate.
• Sensitive sites. Lots near protected areas, wetlands, rivers or springs, or projects listed in the environmental regulation, may need SETENA approval.
• Changes later. Under Articles 12 and 13 of Decree 42075, any change to the tank or drain field design must be authorized by the Ministry of Health before work starts, and an increase in flow, such as adding bedrooms, requires meeting the rules again.

A sensible order of work

1. Get the land use certificate and the water availability letter before you finalize the design.
2. Run the percolation tests while the architect is still sketching, so the drain field fits the site plan.
3. Size the septic system for the real occupancy, especially if the house will be rented.
4. Submit everything together through the CFIA professional.

Ingeniería de las Aguas, in Palmares, Alajuela, designs septic systems and drain fields from the percolation test results, designs treatment plants, and handles wastewater permits with the Ministry of Health, MINAE, SETENA, AyA and municipalities. We work in Guanacaste, the Central and South Pacific, the Central Valley and Limón, and can coordinate with your architect. Learn about our permit management service, or send us the lot location and your plans on WhatsApp or through our contact page.