ISO 11465-2025 PDF

Full title and description

St ISO 11465-2025 — Sludge and solid environmental matrices — Determination of dry residue or water content and calculation of the dry matter fraction on a mass basis. This international standard specifies gravimetric procedures and calculation rules used to report results on a dry-matter basis for sludge, sludge products, treated biowaste, soil and a variety of solid wastes.

Abstract

The standard defines two principal approaches: determination of dry residue (method A) and determination of water content (methods A and B), and provides rules for calculating the dry matter fraction on a mass basis. It applies to samples with more than 1% (mass fraction) of dry residue or more than 1% (mass fraction) of water; method B is intended for liquid wastes and for samples suspected to contain volatile substances other than water. The document replaces the earlier ISO 11465:1993 edition and extends the scope from soil-only procedures to a wider set of environmental matrices.

General information

• Status: Published (International Standard).
• Publication date: August 2025.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.080.20 (Physical properties of soils / environmental matrices).
• Edition / version: Edition 2, 2025.
• Number of pages: 12 pages (published edition).

Scope

ISO 11465:2025 specifies methods for the calculation of the dry matter fraction of sludge, sludge products, treated biowaste, soil and solid waste, based on either a dry-residue determination or a water-content determination. The standard is intended for samples where the dry residue or water content exceeds 1% (mass fraction) and includes special provisions for samples that may contain volatile constituents other than water. It replaces the previous soil-only gravimetric method (ISO 11465:1993) and standardizes reporting to a dry-matter basis across a broader range of environmental sample types.

Key topics and requirements

• Definition of dry residue and water-content determination methods and selection criteria (Method A: dry residue; Method B: water content for volatile-bearing/ liquid samples).
• Procedures for sample handling and calculation of dry matter fraction on a mass basis (reporting results referenced to dry matter).
• Applicability limits (applies where dry residue >1% or water content >1% by mass).
• Requirements and cautions for samples containing volatiles (use of Method B where appropriate).
• Alignment and supersession of the 1993 gravimetric soil method, extending usage to sludge, biowaste and various solid wastes.

Typical use and users

Environmental testing laboratories, waste-management and wastewater treatment facilities, composting and biowaste processors, regulatory agencies, research institutions and consultants use this standard to determine and report solids/dry-matter content for compliance testing, mass-balance calculations, process control and product specification. The standard supports consistent reporting when comparing results across laboratories and sample types.

Related standards

ISO 11465:2025 supersedes ISO 11465:1993 (soil quality — gravimetric dry matter/water content method). Related documents commonly referenced for complementary measurements or sample pretreatment include ISO 11461 (soil water content on a volume basis) and other soil/waste characterization standards such as ISO 10694 (soil carbon determination) and ISO 11464 (sample pretreatment). These related standards provide additional methods for reporting on dry-matter basis or for sample preparation prior to analysis.

Keywords

dry matter; dry residue; water content; gravimetric method; sludge; solid waste; treated biowaste; soil; dry matter fraction; environmental matrices; volatile constituents.

FAQ

Q: What is this standard?

A: ISO 11465:2025 is an international standard that specifies methods for determining dry residue or water content and for calculating the dry matter fraction on a mass basis for sludge, sludge products, treated biowaste, soil and solid wastes.

Q: What does it cover?

A: It covers gravimetric approaches (dry-residue and water-content determinations), rules for selecting the appropriate method (A or B), calculation procedures to express results on a dry-matter basis, and applicability limits (samples with >1% dry residue or >1% water). It also gives guidance for samples suspected to contain volatiles other than water.

Q: Who typically uses it?

A: Environmental and analytical laboratories, wastewater and sludge treatment operators, compost and biowaste facilities, regulators and researchers use the standard for routine analysis, compliance testing, process control and for converting measured concentrations to a dry-matter basis.

Q: Is it current or superseded?

A: ISO 11465:2025 is the current published edition (published August 2025) and supersedes ISO 11465:1993, which has been withdrawn.

Q: Is it part of a series?

A: The standard is maintained by ISO technical committee ISO/TC 190 (soil quality) and complements other soil and environmental analytical standards (for example, methods for sample pretreatment, soil carbon determination and volume‑basis water content). It is part of the ISO family of standards addressing physical and chemical characterization of soils and environmental matrices.

Q: What are the key keywords?

A: Dry matter, dry residue, water content, gravimetric method, sludge, solid waste, treated biowaste, soil, dry-matter fraction.