Tamarindo is one of the busiest beach towns in Costa Rica, and it grew fast. Hotels, condo buildings, surf hostels, restaurants and rental homes sit close together on mostly flat land between the beach and the Tamarindo estuary, with Langosta a few minutes south. Very few of these properties can count on a public sewer, so each one treats its own wastewater, and the conditions here make that harder than it looks on paper.
This page explains what is different about wastewater in Tamarindo and Langosta, what the Costa Rican rules ask of each type of property, and how we can help. Both towns belong to the canton of Santa Cruz, in Guanacaste, so local building permits go through the Municipality of Santa Cruz.
What makes Tamarindo different
Density. Lots are small and buildings are close together. A drain field needs private green space, and Decree 42075-S-MINAE does not allow it under driveways, parking, decks or pavers. It also requires setbacks: 1 meter from property lines and from the nearest building, 1.5 meters from drinking-water pipes and 3 meters from water storage tanks. On a narrow lot with a pool and parking, there is often not enough room left for trenches, which pushes the project toward a compact treatment plant.
Low, flat land near the estuary. The regulation requires at least 1.5 meters between the bottom of a drain field trench and the water table. On low ground near mangroves, the water table can rise close to the surface during the rains, especially in September and October, the wettest months in the North Pacific according to the National Meteorological Institute (IMN). A site that looks dry in March can fail that rule in October.
Sandy soil. Sand drains quickly, which sounds good but is not always acceptable. Trenches are allowed only when the percolation rate falls between 2 and 24 minutes per centimeter. Faster than that, the water reaches the ground before the soil has a chance to clean it. A proper percolation test, done after soaking the ground for 24 hours, tells you where you stand.
Seasonal peaks. High season runs through the dry months, roughly December to April, with Christmas and Easter as the peaks. A hotel or condo that is half empty in June may be full in January. Systems designed for an average week struggle when every room is booked and every kitchen is running.
What each type of property usually needs
Rental homes and villas
A single-family home below 190 cubic meters of monthly water use can use a septic tank and drain field designed under Decree 42075. In Tamarindo we usually recommend an improved septic tank, which adds an upflow anaerobic filter after the tank. Cleaner water reaching the drain field means more margin during full-house weeks. If you rent the house to large groups, the design flow should reflect real occupancy, not the number of people who live there in the off season.
Condominiums
Most condo buildings exceed 190 cubic meters a month, so their wastewater must go through a treatment plant approved under Decree 39887-S-MINAE. Once the plant is running, the condominium is the "generating entity" under the Wastewater Discharge and Reuse Regulation (Decree 33601-MINAE-S): it must keep a logbook, run routine measurements and lab analyses, and file operational reports with the Ministry of Health. Our page on HOA wastewater plant compliance explains those duties. If you are buying a unit, read our due diligence checklist for condos with a treatment plant.
Hotels and restaurants
Kitchens are the main source of trouble: grease reaches the tank or the plant and clogs everything downstream. The rules require a two-chamber grease trap for dishwashing water in septic systems, and a plant needs proper pretreatment too. For small hotels we explain the full path, from design to reports, in our guide on boutique hotel wastewater treatment.
Where the treated water goes
Every design starts with one question: where will the treated water end up? In Tamarindo the realistic options are:
- Infiltration into the ground, when the soil, water table and space allow it.
- Reuse for irrigation of gardens and green areas, which makes a lot of sense in a region with a long dry season. Reuse follows Decree 33601 and the design requirements of Decree 39887, including monitoring wells.
- Discharge to a water body, which needs a discharge permit from MINAE's Water Directorate and pays an environmental fee.
- Connection to a sewer, only where one exists and the operator accepts the connection.
Since a 2024 amendment, Decree 39887 allows these options to be combined. A hotel can, for example, irrigate in the dry season and infiltrate in the rainy one, if the design and permits cover both.
How we help in Tamarindo and Langosta
Ingeniería de las Aguas is an engineering firm based in Palmares, Alajuela, that works across Guanacaste. In this area we can:
- design and build wastewater treatment plants and improved septic systems;
- review, optimize or rehabilitate an existing plant that fails its lab results or smells;
- design drain fields from the percolation test results, and stormwater drainage that keeps rain out of the system;
- prepare operational analyses and reports, and follow up on how a system performs over time;
- handle permits with the Ministry of Health, MINAE, SETENA (the National Environmental Technical Secretariat), AyA (the national water utility) and the Municipality of Santa Cruz;
- supervise construction.
For the bigger picture of the province, see our Guanacaste overview, and before the rains read rainy season and septic systems in Guanacaste.
If you own, manage or are about to buy a property in Tamarindo or Langosta, send us the location, the type of property, the number of rooms or units and a few photos of the current system on WhatsApp, or use our contact page. We will tell you what we see and what the next step should be.