Factor K: What it is and how companies can challenge improper charges

In 2025, Factor K returned to the center of legal and business discussions, bringing financial impacts to industries, commercial establishments, and companies that discharge effluents into the public sewage network. Many business owners are beginning to see an important opportunity: the possibility of recovering amounts unduly paid in recent years. This potential for financial restitution is one of the main triggers prompting companies to review their sewage bills and question the application of Factor K.

What is Factor K and how does it affect your company?

Factor K is a tariff multiplier applied to the sewage bills of establishments that generate waste considered to have a high pollutant load. It is determined based on the Chemical Oxygen Demand (COD) and Total Suspended Solids (TSS) of the effluents discharged into the public network. These parameters indicate the level of pollution in the waste and determine the need for special treatment, justifying the application of a correction factor in the tariff charged.

For companies that transport their effluents to treatment plants, a specific coefficient (K2) is applied, which may vary according to the sector of activity and the characteristics of the industrial waste.

Improper application of Factor K

Factor K is not always charged lawfully. Legislation requires that its application be justified through a technical analysis. Many companies are being charged without proper evidence that their effluents actually require differentiated treatment. Common irregularities identified include:

• Application of Factor K without a specific technical study or without an updated report
• Misclassification of the company’s activity, resulting in a higher coefficient than applicable
• Calculations based on generic values without considering the actual composition of the effluents
• Retroactive charges without adequate documentary justification

Given these inconsistencies, companies may challenge the application of Factor K through administrative or judicial means and, in many cases, claim restitution for amounts unduly paid in recent years. The challenge can be filed through an administrative proceeding before the water and sewage utility (such as SABESP) or through litigation if no satisfactory resolution is reached.

The first step is to obtain an independent technical report to prove that the calculation applied by the utility does not reflect the actual characteristics of the effluent discharged. The main steps in this process include:

1. Technical analysis of the effluents to verify whether the pollutant load actually justifies the charge
2. Review of the tariff classification to identify potential errors in classification
3. Filing of an administrative proceeding to request a billing review
4. Judicial action, if necessary, to claim reimbursement of retroactive amounts

Factor K is, therefore, a legitimate mechanism to adjust charges for the treatment of industrial and commercial wastewater, but its application must follow strict technical criteria. Many companies are being financially impacted by improper charges and may seek restitution of amounts paid in error.

At Coletta Rodrigues Advogados, we have a team specialized in analyzing issues related to Factor K, providing legal support based on current legislation and best practices to ensure proper application of tariff rules. Specialized legal assistance can be essential to clarify doubts and ensure that the criteria applied are in full compliance with the law.