Small craft - Waste systems - Part 1: Waste water retention
1Key Takeaways
This document specifies requirements for the construction, design and installation of sewage systems for temporary storage and subsequent discharge. It applies to small craft with a hull length (LH) not exceeding 24 m. This document does not cover wastewater treatment systems
2Expert Interpretation
An in-depth interpretation of ISO 8099-1:2018, the international standard for wastewater storage systems for small vessels, covers key technical specifications such as system design, material selection, piping installation, and ventilation requirements, providing standardized solutions for wastewater treatment for vessels under 24 meters in length.
Comparison of key technical requirements
| Technical elements | Monohull sailboat | Other ships | Test standards |
|---|---|---|---|
| Maximum tilt working angle | 20° | 7° | Clause 4.5 |
| Anti-siphon tilt angle | 30° | 20° | Clause 6.1-6.2 |
| Tank pressure test | ±20kPa/5min | Clause 4.10 | |
Material and system design specifications
Chapter 5 of the standard specifies that system materials must withstand:
- Corrosion by sewage and oily bilge water
- Chemical action of disinfectants/antifreeze
- Extreme temperatures from -40°C to +60°C
Piping system Requirements (Chapter 6):
- Minimum inner diameter 38mm (if no manufacturer's recommendation)
- Sea valves must comply with the ISO 9093 series of standards
- Pipeline fixation must prevent vibration wear
Key indicators of ventilation system
Depending on the capacity of the storage tank, Chapter 7 of the standard stipulates:
- <400L storage tank: minimum ventilation pipe inner diameter 19mm (can be reduced to 16mm with a pressure relief valve)
- ≥400L storage tank: minimum ventilation pipe inner diameter 38mm (single pipe ≥19mm for multi-pipe combination)
- Flexible storage tank: at least 16mm ventilation pipe
The ventilation system must maintain gas discharge function at a 20° inclination angle and be able to withstand a negative pressure of 20kPa.
Special requirements for storage tanks
Chapter 8 stipulates separately for fixed storage tanks and portable storage tanks:
- Capacity> ＞ 40L requires a ≥ 75mm inspection port
- It is prohibited to share the same wall with fuel/drinking water tanks
- Portable storage tanks must be marked with transportation operation instructions
Recommendations for the implementation of the standard
- Chemically resistant polyethylene material storage tanks are preferred
- The pump outlet joints must be processed strictly in accordance with the thread specifications (ISO 228-1) in Appendix A
- The electrical system must comply with the requirements of ISO 13297 and ISO 10133
- The system must be emptied before winter storage