Flamingo, Potrero and Brasilito sit around the same bay on the northern Guanacaste coast, but they pose very different wastewater problems. Flamingo is a hill covered with ocean-view villas and condominiums, many on steep, rocky lots. Potrero and Brasilito are flatter towns with small lots, local businesses, restaurants and vacation rentals close to the beach. All three are in the canton of Santa Cruz, so local construction permits go through the Municipality of Santa Cruz.
Here is what we look at in each, and how the Costa Rican rules shape the answer.
Flamingo: slopes, rock and views
The best views come with the hardest sites. Decree 42075-S-MINAE, the national regulation for disposing of treated wastewater into the ground, sets three rules that weigh heavily on a hillside:
- No drain field on slopes steeper than 30 %.
- Level trenches. The trench bottom and the drain pipe must be horizontal, so on a slope they follow the contour lines.
- A 2-meter setback from the top of any slope steeper than 25 %. Every terrace you cut for the house or the pool creates a new slope and eats into the space you had for the drain field.
On top of that, rock close to the surface makes infiltration poor and excavation slow. The practical lesson is simple: decide where the wastewater goes before you fix the house layout. If the only area with suitable soil is below the house, a small pumping station can move the treated water there. If no area works, the design can turn to reuse for irrigation or another approved method.
Condominiums on the hill
Condo developments in Flamingo typically exceed 190 cubic meters of monthly water use, the limit above which a septic tank is not enough. Their wastewater goes to a treatment plant approved under Decree 39887-S-MINAE, often with pumping, because units sit at different levels and the plant has to go where there is space. Once the plant runs, the condominium must file operational reports with the Ministry of Health. Our page on HOA wastewater plant compliance explains what that involves.
Potrero and Brasilito: small lots on low ground
Down by the beach, slope is not the issue. Space and groundwater are.
- Small lots leave little private green area for trenches. The drain field cannot go under parking, driveways or pavers, and must keep 1 meter from property lines and buildings.
- Low ground near the beach and streams can have a high water table in the rainy season. The regulation requires 1.5 meters between the trench bottom and the water table.
- Mixed uses. A house with two rental units and a small shop behind it can produce much more wastewater than a family home. The design flow must reflect real use, which we explain in our guide on sizing a septic system.
For restaurants and sodas (small local eateries), the grease trap is the first line of defense. The regulation requires a two-chamber grease trap for dishwashing water in septic systems, cleaned every three months.
Dry season and water reuse
The National Meteorological Institute (IMN) describes Guanacaste as one of the least water-rich regions in Costa Rica, with a dry season of five to six months starting in December. That makes treated water valuable. A hotel or condo plant can be designed to irrigate gardens with treated water, under the reuse rules of Decree 33601-MINAE-S and the design requirements of Decree 39887. Since a 2024 amendment, infiltration, reuse, discharge and evaporation can be combined in one design. For homes, read our guide on greywater and reuse first: untreated greywater cannot simply go to the garden.
How we help in Flamingo, Potrero and Brasilito
Ingeniería de las Aguas, based in Palmares, Alajuela, works across Guanacaste. In this area we:
- design and build improved septic systems for homes and villas;
- design, build, upgrade and rehabilitate wastewater treatment plants for condos, hotels and commercial buildings;
- design pumping stations, sanitary sewers and stormwater drainage for hillside developments;
- design drain fields from the percolation test results;
- prepare operational analyses and reports and follow up on system performance;
- handle permits with the Ministry of Health, MINAE, SETENA, AyA and the Municipality of Santa Cruz.
If you are also looking at Tamarindo, compare with our page on Tamarindo and Langosta, or see the Guanacaste overview.
To talk about your lot or your current system, send us the location, a few photos and, if you have them, the plans, on WhatsApp or through our contact page.