Wastewater Discharge Regulations in Paraguay: A Practical Guide
What MADES requires to discharge effluent in Paraguay: Law 294/93, Law 3239/07, the environmental license and parameters like BOD, COD, solids and pH.
To discharge treated wastewater in Paraguay, an industry or municipality needs an environmental license from MADES (Ministry of the Environment and Sustainable Development), obtained through the Environmental Impact Assessment set out in Law 294/93, and must comply with the framework of Law 3239/07 on Water Resources. The discharged effluent has to meet quality limits (BOD, COD, total suspended solids, pH, oils and grease, among others) defined by the applicable environmental regulation. Exact limits change over time and depend on the receiving body, so you should always verify them with MADES before designing the plant.
Who regulates wastewater discharge in Paraguay
The governing body is MADES. It is the enforcement authority for environmental policy and the entity that grants, conditions or rejects the environmental license that allows a facility to operate and discharge effluent.
In practice, any project generating discharges with a meaningful organic or chemical load —a slaughterhouse, a dairy plant, a tannery, a brewery, a housing development with a sewage plant— falls within MADES oversight. Discharging without a license exposes the company to fines, shutdown and environmental liability.
The legal framework: Law 294/93 and Law 3239/07
Law 294/93 — Environmental Impact Assessment
This is the law that creates the Environmental Impact Assessment (EIA) instrument. It establishes that works and activities capable of generating impact —including the generation and disposal of effluent— must submit an environmental study and obtain an Environmental Impact Declaration, which takes the form of the environmental license.
The study describes the project, characterizes the effluent, proposes the treatment technology and defines a management and monitoring plan. It is the base document on which MADES decides.
Law 3239/07 — Water Resources
It governs the integrated management of water in Paraguay: its use, exploitation and protection. It is the framework that backs the requirement that a discharge must not degrade the quality of the receiving body —a stream, a river or an aquifer— and that water use be orderly and, where applicable, authorized.
The environmental license process, step by step
- Effluent characterization: flow rate and laboratory analysis of the raw effluent (BOD, COD, solids, pH, nutrients, grease).
- Environmental Impact Study: the EIA (or the basic environmental questionnaire, depending on project scale) is prepared with the engineering of the proposed treatment system.
- Submission to MADES: filing of the study and the facility's technical and legal documentation.
- Review and comments: MADES reviews and may request clarifications or adjustments to the project.
- License issuance: the environmental license is issued with conditions, discharge limits and a monitoring plan.
- Renewal and follow-up: the license has limited validity and requires periodic monitoring and renewal.
Typically monitored discharge parameters
The regulation sets maximum values for a set of parameters. The ranges in the table below are common orders of magnitude in discharge standards for surface water bodies in the region, shown for orientation only; they do not replace the official limits, which must be verified with MADES for each case and receiving body.
| Parameter | What it measures | Indicative limit range (surface discharge) |
|---|---|---|
| pH | Acidity / alkalinity | Approx. 6 to 9 |
| BOD₅ (biochemical oxygen demand) | Biodegradable organic matter | Order of 50 to 120 mg/L |
| COD (chemical oxygen demand) | Total oxidizable organic matter | Order of 150 to 250 mg/L |
| Total suspended solids | Particulate material | Order of 50 to 150 mg/L |
| Oils and grease | Fats and hydrocarbons | Order of 20 to 50 mg/L |
| Temperature | Thermal shock to the receiver | Typically below 40 °C |
| Nitrogen and phosphorus | Nutrients (eutrophication) | Depends on receiving body |
The key point: the more demanding the receiving body and the applicable limit, the more robust the treatment train must be. A discharge that only needs to bring BOD down to 120 mg/L does not require the same as one that must reach 30 mg/L for reuse or discharge into a sensitive watercourse.
How the regulation connects to plant design
The license is not separate from the engineering: it defines the limits the plant must meet. That is why it pays to size the treatment against the required parameters from the start. A common approach combines pretreatment, an anaerobic reactor such as the UASB reactor to remove most of the organic load, and a final aerobic polishing step to reach BOD and solids limits.
At Tech Tank we approach this as an integrated project: the wastewater treatment (ETE) solution is designed as a turnkey package, so that engineering, bolted steel tanks, installation and commissioning are all aligned with the discharge quality the license requires. If you are evaluating a project in Paraguay, you can bring us your case and we will review the technical and regulatory path with you.
Frequently Asked Questions
Do I need a MADES environmental license to discharge effluent?
Yes. Any activity that generates effluent with environmental impact requires an environmental license from MADES, obtained through the Environmental Impact Assessment under Law 294/93. Discharging without a license exposes you to penalties, shutdown and legal liability.
Which laws regulate wastewater discharge in Paraguay?
Mainly Law 294/93 on Environmental Impact Assessment, which creates the environmental license, and Law 3239/07 on Water Resources, which protects water quality. MADES is the enforcement authority. Specific limits are set by the applicable regulation.
Which discharge parameters are most closely controlled?
The most common are pH, BOD, COD, total suspended solids, oils and grease, temperature and, depending on the case, nitrogen and phosphorus. Maximum values depend on the receiving body and should be confirmed with MADES.
Are discharge limits fixed across the whole country?
Not necessarily. They depend on the type of effluent, the activity and above all the receiving body. A sensitive watercourse or a downstream water use may require stricter limits. That is why you must always verify the current regulation and license conditions with MADES.
How long does it take to obtain the environmental license?
It depends on the complexity of the project and the quality of the study submitted. A well-prepared EIA, with the treatment engineering resolved and the effluent properly characterized, reduces comments and speeds up the process.
Should I design the plant before or after the license?
They go together. The treatment engineering is part of the study submitted to MADES, and the limits the license will impose determine how the plant is sized. The most efficient approach is to handle regulation and design in an integrated way.