Overview
ISO/TR 24524:2019 is a Technical Report from ISO/TC 224 that describes the hydraulic, mechanical and environmental conditions typically found in wastewater transport systems - from toilets and household drain lines through sewers, pumping stations and on to wastewater treatment plants. It is a guidance document (a technical report, not an International Standard) intended to help wastewater services, product manufacturers and regulators understand operating conditions, the powers of wastewater services to manage discharges, and responsibilities imposed by local, regional or national legislation.
Key Topics
- Toilets and flush characteristics
- Purpose and function of toilets; variation in toilet designs and flush volumes (examples in the report include northern Europe ~2–4 L, Japan ~6–10 L).
- How toilet configuration affects the ability of materials to pass into drain lines.
- Drain lines and intermittent flow hydraulics
- Typical drain-line configurations and intermittent-flow behaviour.
- Clearance issues that lead to stranding, settling and snagging of solids.
- Wastewater transport hydraulics
- Typical transit times, flow regimes and indicators such as Reynolds number that describe laminar vs. turbulent flow in pipes.
- Screening and mechanical protection
- Role of screens, grilles and other devices to collect solids and protect pumps and downstream infrastructure from clogging.
- Treatment process interactions
- Primary settlement, biodegradation of settled solids and the liquid phase characteristics relevant to treatment performance.
- Environmental considerations
- Impacts of discharged materials (including plastics and microplastics), compatibility with treatment processes and receiving environments.
- Definitions and legal/operational context
- Terms (aligned with ISO 24513 vocabulary), and summary of wastewater services’ general powers and legislative responsibilities.
Applications
ISO/TR 24524:2019 is practical guidance for:
- Wastewater utilities and operators - diagnosing root causes of sewer blockages, setting operational limits, and designing screening and pumping arrangements.
- Product manufacturers (toilet paper, wipes, personal-care items) - evaluating whether products are likely to disintegrate, transport through sewers, and be compatible with treatment processes (i.e., assessing “flushability”).
- Plumbing and civil engineers - designing drain lines, sewers and pump stations with realistic hydraulic and mechanical loads in mind.
- Regulators and policy makers - informing discharge rules, by-laws and public guidance to reduce sewer blockages and environmental impacts.
- Environmental consultants and asset managers - assessing impacts of discharged material (e.g., microplastics) on treatment performance and the receiving environment.
Related Standards
- ISO 24513 - Vocabulary for service activities relating to drinking water supply, wastewater and stormwater systems (normative reference used by ISO/TR 24524:2019).
Keywords: ISO/TR 24524:2019, wastewater transport systems, sewer blockages, toilet flushable, drain line hydraulics, Reynolds number, wastewater treatment, screening, microplastics.
Open preview (PDF)Service activities relating to drinking water supply, wastewater and stormwater systems — Hydraulic, mechanical and environmental conditions in wastewater transport systems
