Against the backdrop of the global shipping industry’s growing demand for energy conservation, emission reduction, and green ship construction, Norwegian vacuum drainage technology expert JETS®, leveraging decades of industry experience and technical expertise, continues to provide efficient sanitation solutions for commercial vessels, ocean-going cargo ships, and offshore platforms. Its intelligent vacuum sanitation solution (including vacuum toilets and sewage treatment systems) breaks the physical limitations of traditional gravity drainage systems: gravity drainage systems rely on water flow to transport sewage, while vacuum sanitation systems primarily rely on air pressure for transportation. In actual operation, the vacuum sanitation system uses only about 1 liter of water per flush, which is used solely for sanitary cleaning and does not serve a sewage transport function.
This system has achieved large-scale implementation globally, with over 300,000 vacuum toilets and 60,000 Vacuumarator® vacuum pumps delivered cumulatively. Compared to traditional gravity drainage, this system not only achieves approximately 83% water savings but also, through 80%–85% sewage volume reduction management, flexible “anti-gravity” small-diameter piping design, and low failure and maintenance rates, helps shipowners significantly free up cargo space and reduce overall operational costs. It provides high-quality equipment and excellent service support throughout the ship’s lifecycle, becoming one of the core technological engines driving the upgrade of modern green shipping.
Performance Benchmark: Differences Between Vacuum Technology and Gravity Drainage
From a single flush to daily navigation, the vacuum sanitation system significantly outperforms traditional gravity drainage systems in terms of water consumption, sewage generation, and treatment load. With this system, ships can adopt more compact sewage treatment and storage configurations, thereby improving space utilization efficiency and reducing operational burdens.
Save Thousands of Liters of Water – Every Day
System Volume Optimization: Derived from Reduced Water Consumption
JETS®, as a globally renowned supplier of vacuum sanitation systems, currently has over 570,000 vacuum toilets in operation. Compared to traditional marine toilets, these devices can save approximately 27 million liters of fresh water daily, thereby reducing the overall water load on ships.
In practical applications, the water-saving effect of the vacuum sanitation system varies depending on the ship type and crew size:
By Ship Type
– Small vessels: Daily fresh water consumption can be reduced by tens of thousands of liters, significantly lowering fresh water demand.
– Cargo ships or offshore platforms: After adopting the vacuum sanitation system, several tons of fresh water can be saved each day.
By Passenger Capacity
– Approximately 300-person vessel (60% occupancy): The vacuum sanitation system uses about 1.3 cubic meters of water per day, while the gravity drainage system uses about 7.8 cubic meters, saving approximately 6.5 cubic meters (about 83%).
– Approximately 2,000-person vessel (60% occupancy): The vacuum sanitation system uses about 7.4 cubic meters of water per day, while the gravity drainage system uses about 44 cubic meters, saving approximately 36 cubic meters (about 83%).
Space Optimization: Enhancing Cargo Efficiency Through Volume Reduction
Compared to traditional gravity drainage systems, the vacuum sanitation system achieves sewage volume reduction through lower flush water consumption, alleviating sewage treatment and storage pressure at the source.
– Low Water Consumption: Vacuum toilets require less water per flush, resulting in a smaller total volume of sewage generated, which is also more concentrated. Some ships can store sewage for centralized treatment after docking, thereby reducing the impact on the marine environment during navigation.
– Low Sewage Volume: The vacuum sanitation system can reduce sewage generation by approximately 80%–85%. For example, a ferry’s sewage volume is only 17% of that of a gravity drainage system. Taking a vessel with about 300 people as an example, the vacuum sanitation system generates only about 1.3 tons of sewage per day, while the gravity drainage system generates nearly 8 tons. This significant reduction in sewage volume lowers treatment and storage requirements, allowing ships to be equipped with smaller capacity sewage storage tanks and more compact sewage treatment equipment, thereby reducing equipment footprint and system weight, and decreasing the frequency of discharge at ports.
As flush water consumption decreases, the ship’s demand for fresh water reserves also diminishes, allowing for smaller fresh water tank capacities or extended replenishment intervals. For shipowners, this not only helps reduce the frequency of water replenishment and related costs but also frees up more tank capacity and cargo weight resources for fuel or cargo configuration, thereby enhancing cargo capacity and optimizing fuel utilization efficiency.
Operational and Design Advantages: Comprehensive Breakthrough of Traditional Limitations
Image source: Cecilie Hatløy
In addition to water-saving and volume reduction advantages, the vacuum sanitation system offers several practical values in offshore operations:
– Not Limited by Gravity: Vacuum toilets achieve horizontal or upward discharge through small-diameter pipes, suitable for complex ship environments, such as when toilets are located below the waterline or far from the sewage storage area. The equipment transports sewage via negative pressure without relying on gravity, reducing pipe residue, thereby lowering daily cleaning and maintenance workload and improving overall operational efficiency.
– Space and Weight Savings: The vacuum sanitation system uses small-diameter pipes of approximately 50 mm, whereas gravity drainage systems typically use large-diameter pipes of 100 mm or more. This reduces the space occupied by piping, as well as system weight, installation time, and cost. In space-constrained areas like engine rooms, the small-diameter design helps improve space utilization. Since no ventilation shafts are required, the vacuum sanitation system can also free up more space for equipment arrangement and cargo loading. Additionally, vacuum piping layout is flexible, allowing installation along slight slopes or upwards according to the cabin structure, even extending through overhead spaces to higher decks, providing more layout options for new builds and retrofit projects, and simplifying the installation and modification process.
– Reduced Clogging Risk: Traditional gravity drainage systems are prone to residue and clogging in large-diameter pipes or U-bends, affecting discharge efficiency. In contrast, the vacuum sanitation system, through high-speed airflow and a macerating discharge mechanism, effectively prevents various pipe clogging risks, ensuring smooth system operation.
– Improved Sanitary Environment: Traditional gravity flush systems, under conditions of inadequate ventilation, can generate and spread bacteria-containing aerosols, posing sanitation management challenges in the enclosed ship environment. Vacuum toilets, however, use negative pressure to quickly draw sewage into the pipes, producing almost no aerosols during the flush process, thereby reducing the risk of bacterial transmission and odor diffusion in the restroom. Furthermore, the vacuum sanitation system uses a closed conveyance method; even if a pipe leak occurs, it is usually external air entering the system, which may cause a drop in vacuum level and trigger operational alarms, but will not result in sewage leakage. In contrast, when a gravity drainage system pipe leaks, sewage may flow directly out of the pipe, increasing cleaning and sanitation management burdens. Therefore, using a vacuum sanitation system helps control odors, improve onboard hygiene levels, and enhance crew comfort.
– Reliability and Low Maintenance Costs: Compared to the frequent leaks, clogs, or mechanical failures that may occur with gravity drainage systems, the vacuum sanitation system has a compact structure with few moving parts. Supplemented by vacuum pumps (such as the JETS® Vacuumarator®), it can reduce failure rates and daily maintenance needs, maintaining long-term stable operation. The high reliability of this system under frequent daily use helps alleviate maintenance pressure on the crew and ensures continuous operation on long voyages.
Environmental and Regulatory Advantages: Ensuring Compliance Throughout the Ship’s Lifecycle
As the global shipping industry’s requirements for environmental protection and emission management continue to tighten, vacuum sanitation systems are rapidly becoming an indispensable and important component of green ship operations.
Regarding alleviating sewage discharge pressure, the significant reduction in sewage volume allows ships to extend intervals between sewage discharges, enabling longer navigation in areas where discharge is prohibited (coastal or ecologically sensitive waters). Some ships equipped with vacuum sanitation systems can achieve “zero discharge” operations in sensitive areas—temporarily storing the small volume of highly concentrated sewage for compliant disposal at an opportune time, in line with the environmental regulations of Annex IV of the International Convention for the Prevention of Pollution from Ships (MARPOL).
Regarding resource efficiency, water conservation onboard means reducing the demand for water production and port-side fresh water replenishment. In the long term, reduced water consumption directly lowers the ship’s own weight and related fuel consumption, helping to reduce operational resource pressure and carbon footprint. The 80% reduction in flush water also simultaneously reduces energy consumption in water production and sewage treatment processes.
Regarding sustainable development, choosing this vacuum sanitation system can meet daily usage needs while reducing unnecessary water consumption and sewage discharge, providing shipowners with a green operational solution that balances functionality and economic benefits. As the shipping industry’s green and low-carbon standards continue to rise, its commercial value in energy conservation, emission reduction, and regulatory compliance is increasingly gaining attention.
JETS® vacuum sanitation systems are suitable for the application needs of different ship types, including bulk carriers, container ships, tankers, and commercial vessels. They can be customized into comprehensive implementation solutions based on ship type, crew size, and operational requirements, supporting green shipping, lightweight management, and water-saving and emission reduction strategies, helping shipowners achieve efficient operations while ensuring crew comfort. For more information on JETS® vacuum drainage technology solutions, please visit its official website.
