When someone with a rural plot without a sewer connection hears about Decreto 46, the first reaction is usually concern: will I have to comply with an emission standard with dozens of parameters? For a family home, the answer is almost always reassuring. DS 46 exists to control establishments that discharge large pollutant loads into the subsoil, not the family living on its plot. It is worth understanding why, because the same regulation pinpoints exactly where the real risk to groundwater lies.
What is Decreto 46?
Decreto Supremo 46 of 2002 (Ministerio Secretaría General de la Presidencia) is called the Norma de emisión de residuos líquidos a aguas subterráneas (emission standard for liquid waste discharged to groundwater). It was enacted on 8 March 2002 and published on 17 January 2003. Its aim is to prevent pollution of groundwater when an effluent seeps into the ground, and to that end it sets maximum values for around thirty substances, depending on the vulnerability of the aquifer at each location.
Today this regulation is enforced by the Superintendencia del Medio Ambiente (SMA, the environmental superintendency). You can consult the official text in the Biblioteca del Congreso Nacional (Ley Chile, idNorma 206883).
Does it apply to the house on my plot?
As a general rule, no. The regulation only considers an establishment an emission source when its average daily pollutant load exceeds that of a reference establishment of around 100 PE (population equivalent). A home for four to six people falls far below that, so it is normally not an emission source and is not directly subject to DS 46.
There is concrete precedent: in one documented case, the SMA analysed a septic tank with a drainage system and concluded that its infiltration did not qualify as a potential emission source. In addition, the permit for a domestic plant is not processed under DS 46, but with the Seremi de Salud (regional health authority), under the Código Sanitario and the regulation on private sewer systems. In short: for your house, the usual route is the sanitary one, not this emission standard.
And if the project exceeds 100 population equivalents?
Then the picture changes. A housing development, hotel or condominium that lets the treated wastewater of more than around 100 PE seep into the ground is, as a rule, an emission source under DS 46. Its effluent must meet the limits of the standard according to the vulnerability of the aquifer, and the operator needs a monitoring programme set by the authority and reported to the SMA.
If the treated water is discharged into a river, stream or the sea, it is not DS 46 that applies but DS 90 of 2000, the standard for discharges to surface waters. A plant serving 2,500 inhabitants or more must also go through the environmental impact assessment system (SEIA). The health permit from the Seremi de Salud is still required in every case.
For these sizes AQUATO offers the ORKA, designed for each project and with modules for nitrogen and phosphorus removal. As with a single home, we do not promise a compliance figure without measurements: together with you and your engineer we clarify the discharge point, the applicable standard and a design that meets it.
What the regulation does teach
The fact that DS 46 does not bind your home does not mean it has nothing to tell you. At heart, the regulation is a map of what really harms groundwater. And among all its parameters, two are the ones that truly matter in domestic wastewater: nitrogen, and oils and fats. They are precisely the ones a septic tank cannot treat.
DS 46 values for the critical domestic parameters.
| Parameter | Medium vulnerability | Low vulnerability |
|---|---|---|
| Total Kjeldahl nitrogen (TKN) | 10 mg/l | 15 mg/l |
| Nitrate + nitrite (as N) | 10 mg/l | 15 mg/l |
| Oils and fats | 10 mg/l | 10 mg/l |
Why the septic tank falls short
A septic tank is essentially a settling tank. It holds back the solids and lets the rest seep away, but it adds no oxygen and no controlled biological process. That is why it hardly reduces dissolved nitrogen at all and carries a good share of the oils and fats into the effluent. These are the two parameters the regulation monitors most closely, and they are also the two that the septic tank does not control.
Septic tank versus biological plant on the critical parameters.
| Parameter | Septic tank | Biological plant (SBR / SSB process) |
|---|---|---|
| Organic matter (BOD5) | Partial reduction through settling | Reduction ≥ 95% in the type test |
| Organic matter (COD) | Partial reduction | Reduction ≥ 90% in the type test |
| Nitrogen | Practically no reduction | Nitrogen removal possible with the SSB® process |
| Oils and fats | Accumulate and pass into the effluent | Biological breakdown in the aerated reactor |
| Odour | Anaerobic, with odour | Aerobic, odourless |
Clean water starts where it originates: on your own plot.
An honest clarification: for nitrogen we do not state a test value that corresponds one to one to the DS 46 parameter. What is clear is the principle: a biological plant with denitrification actively reduces nitrogen, while a septic tank does not. That is why we do not promise a DS 46 compliance figure, but a process designed precisely for the parameter where the septic tank fails.
The permit in practice
For a home, the permit is processed with the Seremi de Salud: approval of the private wastewater project and, after construction, authorisation of the works. The platform is Seremi en Línea, using ClaveÚnica (the Chilean state's single digital login). Ektennsa prepares the technical documentation together with the professional in charge of your project, but does not replace a lawyer or a permitting specialist.
This article is general guidance based on the regulations in force as of 2026 and does not replace legal advice or review by the competent authority. Every site and every project has its particularities, above all regarding aquifer vulnerability, which in Chile is determined case by case by the DGA (Dirección General de Aguas, the national water directorate). If you have specific questions, consult the health authority or a professional.
