Open-loop scrubber discharge is banned or restricted in 45 countries globally. Meeting the IMO washwater parameter limits under MEPC.259(68) or MEPC.340(77) is not enough by itself. Whether discharge is permitted at all depends on where the vessel is operating. For ships trading through Singapore, Chinese ports, the North-East Atlantic or a growing list of other locations, open-loop discharge is already prohibited in port waters regardless of what the monitor reads.
This article maps the current restrictions by region and port, explains the legal basis for each, covers the OSPAR Decision 2025/01 timeline that will significantly expand restrictions across European waters from 2027, and sets out what voyage planning needs to address to keep scrubber-equipped ships compliant. For the full regulatory framework governing washwater monitoring, see the exhaust scrubber washwater discharge monitoring explainer page.
| Key thing to remember The geographic restriction map is not fixed. It has expanded continuously since the first port-level bans emerged in 2019 and is set to expand further under OSPAR Decision 2025/01. The restrictions that apply today are not the same as those that applied when a vessel’s EGCS was installed. Voyage planning must include a current check of the rules for each port and coastal jurisdiction on the route, not a single reference to a list compiled for a previous voyage. |
Why Do Geographic Restrictions on Scrubber Discharge Exist?
Geographic restrictions on open-loop scrubber discharge exist because the IMO’s global washwater discharge criteria were developed as a baseline for open-ocean discharge. Coastal states, port administrations and regional conventions have concluded that these global criteria do not provide adequate protection in more sensitive coastal environments, ports, estuaries and enclosed seas.
The scientific and policy basis for restrictions draws on several concerns:
- PAH and other contaminants discharged near coastlines, in estuaries and in enclosed seas do not disperse as readily as in open ocean conditions, leading to higher local concentrations
- Repeated discharge by large numbers of vessels in busy ports and shipping lanes creates cumulative effects that single-vessel assessments do not capture
- Some ports and coastal states identified through monitoring that washwater discharge was contributing to measurable deterioration in near-shore water quality
- Regional conventions such as OSPAR and HELCOM operate to higher environmental protection standards than the global IMO baseline and have the legal authority to impose stricter requirements in their respective areas
IMO resolution MEPC.1/Circ.899 gives Member States a risk and impact assessment framework to justify the introduction of restrictions or bans within their waters. This resolution is the legal and technical bridge between the global IMO framework and the growing body of national and port-level controls. PPR 13 in February 2026 continued IMO discussions on potential further global control measures, with PPR 14 invited to receive concrete proposals.
Where Is Open-Loop Scrubber Discharge Currently Banned or Restricted?
The table below sets out the key restrictions by location, their current scope and the legal basis for each. This is based on information available at the time of publication. Operators must verify current restrictions from official port authority, coastal state and classification society sources before each voyage.
| Location | Current restriction | Legal basis | Operational priority |
| North-East Atlantic (OSPAR) | Open-loop discharge banned in internal waters and port areas by 1 July 2027; all-mode discharge banned by 1 July 2029 under OSPAR Decision 2025/01. Roadmap for territorial seas under active consideration. | OSPAR Decision 2025/01 (2025) | High — imminent deadline for major European trading routes |
| Baltic Sea | Scrubber washwater discharge subject to the stricter requirements of the Helsinki Convention (HELCOM) and national legislation of individual Baltic states. Check current national rules for each coastal state on the route. | HELCOM and national legislation | High — significant trading route for European fleet |
| Singapore | Open-loop scrubber discharge prohibited in Singapore port waters. Hybrid systems must switch to closed-loop mode. Applies to all ships calling Singapore, regardless of flag. | Maritime and Port Authority of Singapore (MPA) | Very high — one of the world’s busiest ports |
| Port of Fujairah (UAE) | Open-loop and hybrid scrubber washwater discharge prohibited in Fujairah port waters and offshore anchorage. Resulting waste must be stored onboard for disposal ashore. One of the strictest port-level restrictions globally. | Port of Fujairah Authority | High — major bunkering hub |
| China | Open-loop scrubber discharge banned within Chinese territorial waters for ships calling at Chinese ports, under national environmental regulations. In some emission control zones within Chinese waters the restriction extends further offshore. | Chinese national regulations and MARPOL ECA implementation | Very high — China is a major trading destination for global fleet |
| United States | Federal waters: no ban on open-loop discharge. State-level restrictions vary. California prohibits open-loop scrubber discharge in state waters. Further restrictions in some other US coastal states. Check current state regulations for each port call. | US state environmental regulations (varies by state) | Medium to high — depends on US ports visited |
| Norway | Norwegian regulations restrict or prohibit EGCS discharge in specific Norwegian fjords and coastal areas designated as particularly sensitive. Check current Norwegian Maritime Authority guidance. | Norwegian Maritime Authority and environmental regulations | Medium — relevant for cruise and offshore sectors |
| Belgium | Open-loop scrubber discharge restrictions apply in Belgian territorial waters under national implementing legislation. Subject to further development under OSPAR Decision 2025/01. | Belgian national legislation and OSPAR | Medium |
| Germany | Restrictions on EGCS discharge in German inland waterways and some coastal areas. Subject to further development under OSPAR Decision 2025/01. | German national legislation and OSPAR | Medium |
| Ireland | Restrictions on open-loop EGCS discharge in Irish waters under national implementing legislation. Subject to further development under OSPAR Decision 2025/01. | Irish national legislation and OSPAR | Medium |
| Global (45+ countries) | OSPAR’s 2025 background documentation confirms restrictions exist in 45 countries globally. 13 states or regions prohibit EGCS discharge throughout their territorial waters based on available official documentation. | Various national legislation | Requires voyage-specific research |
| This table is a reference, not a real-time source The geographic restriction map changes regularly as new port-level bans are announced, national legislation is updated and regional frameworks develop. The information in this table reflects the position at the time of publication. Before each voyage, operators must verify the current restrictions for every port and coastal jurisdiction on the route from official sources. Do not rely on this table or any single aggregated source as a substitute for voyage-specific verification. |
What Is OSPAR Decision 2025/01 and What Does It Mean for European Trading?
OSPAR Decision 2025/01 is the most significant development in the geographic restriction landscape since the first port-level bans emerged. It is a binding decision of the OSPAR Convention, which covers the North-East Atlantic including the waters of north-west European coastal states.
OSPAR Decision 2025/01 requires all OSPAR Contracting Parties to implement national legislation prohibiting EGCS discharge in internal waters and port areas within their jurisdiction according to the following timeline:
| Date | OSPAR Decision 2025/01 requirement |
| 2025 | OSPAR Decision 2025/01 adopted. Establishes the binding roadmap for all OSPAR Contracting Parties. |
| 1 July 2027 | Deadline for OSPAR Contracting Parties to implement national prohibition on open-loop EGCS discharge in internal waters and port areas. |
| 1 July 2029 | Deadline for OSPAR Contracting Parties to implement national prohibition on EGCS discharge in any mode (open-loop and closed-loop bleed-off) in internal waters and port areas. |
| Post-2029 | OSPAR roadmap includes consideration of extending geographic coverage to territorial seas. Discussions ongoing. No confirmed deadline for territorial seas phase at time of publication. |
The OSPAR Contracting Parties include Belgium, Denmark, Finland, France, Germany, Iceland, Ireland, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. Ships trading in the North-East Atlantic area — including the English Channel, the North Sea, the Irish Sea, the Bay of Biscay and the waters around Scandinavia and the Iberian Peninsula — will be affected by these requirements when national implementing legislation is in place.
| 2027 and 2029 deadlines require action now The 2027 deadline for open-loop discharge prohibition in internal waters and port areas is less than two years away. Operators trading regularly through OSPAR waters need to assess their options now: holding tank capacity for retained washwater, fuel switching arrangements for restricted legs, and shore reception availability at the ports they call. Leaving this assessment until 2026 or 2027 will not leave enough time to make the necessary operational changes. |
How Does Singapore Regulate Open-Loop Scrubber Discharge?
Singapore prohibits open-loop scrubber discharge in Singapore port waters. The prohibition applies to all ships calling Singapore regardless of flag state. Ships fitted with hybrid EGCS must switch to closed-loop mode when in Singapore port waters.
Singapore was one of the earliest and most significant ports to implement a discharge ban, announcing the prohibition in 2019 ahead of the IMO 2020 sulphur cap. With approximately 100,000 vessel calls per year, Singapore is the world’s busiest bunkering port and the restriction has significant operational implications for scrubber-equipped ships on global trade routes.
Operators should confirm the current scope of the Singapore restriction with the Maritime and Port Authority of Singapore (MPA) before each call, as the regulatory position can be updated by port circular.
What Are the Restrictions in China?
China prohibits open-loop scrubber discharge within Chinese territorial waters for ships calling at Chinese ports, under national environmental regulations. In some areas covered by China’s domestic emission control areas (DECAs), restrictions may apply further offshore.
Given the volume of shipping calling Chinese ports, this restriction affects a very large proportion of the global scrubber-equipped fleet. The restrictions are implemented through Chinese national environmental and maritime legislation rather than through a single document, and operators should verify current requirements with the relevant Chinese port authority or through their classification society for each specific port call.
What Happens to Closed-Loop Bleed-Off Discharge in Restricted Areas?
Closed-loop EGCS systems produce a smaller bleed-off stream that must also be discharged periodically. In some jurisdictions, restrictions apply not only to open-loop discharge but to EGCS discharge in any operating mode, including closed-loop bleed-off.
Where bleed-off cannot be discharged, it must be retained onboard in a holding tank and delivered to a shore reception facility. Operators trading in areas where closed-loop bleed-off is restricted need to confirm:
- Whether their holding tank capacity is sufficient for the restricted leg
- Whether shore reception facilities are available at the ports on the route
- How retained washwater and EGCS residues will be logged in the EGCS Record Book
OSPAR Decision 2025/01 explicitly covers discharge in any mode from 2029, meaning both open-loop discharge and closed-loop bleed-off will be prohibited in OSPAR internal waters and port areas after that date. This is a more significant operational constraint than the pre-2029 open-loop-only restriction and requires longer lead time for operational planning.
Is Open-Loop Discharge Permitted in International Waters?
Open-loop scrubber discharge is generally permitted in international waters where no specific national or regional restriction applies, provided the washwater meets the IMO parameter limits under MEPC.259(68) or MEPC.340(77). Outside territorial waters and the jurisdictions with specific restrictions, the global IMO framework governs discharge.
However, operators should be aware of two important qualifications:
- Passage through territorial waters: ships transiting territorial waters of states with discharge bans must stop discharge when entering those waters, even if the destination port is in international waters. The restriction applies from the moment the vessel enters territorial waters.
- Particularly Sensitive Sea Areas (PSSAs): IMO PPR 13 discussed potential further control measures linked to Particularly Sensitive Sea Areas, with PPR 14 invited to receive concrete proposals. PSSAs could provide a further mechanism for restricting EGCS discharge in ecologically sensitive international waters in the future.
How Should Operators Plan Voyages to Manage Geographic Restrictions?
Managing geographic restrictions on scrubber discharge requires discharge management to be integrated into voyage planning as a standard operational step. The checklist below sets out the key actions for each voyage.
| Step | What to do |
| Identify all ports and coastal waters on the voyage | Compile a list of every port, coastal area and territorial water that the vessel will pass through or call at during the voyage. |
| Check current restrictions for each jurisdiction | For each location, check the current official guidance from the port authority, coastal state maritime administration or classification society. Do not rely on a single aggregated source. |
| Confirm EGCS mode capability | Confirm whether the vessel can switch from open-loop to closed-loop mode and what the holding capacity is for retained washwater in closed-loop operation. |
| Assess fuel switching option | For routes where all EGCS discharge is prohibited, confirm whether switching to compliant low-sulphur fuel is operationally and commercially feasible. |
| Plan holding capacity for zero-discharge legs | Where discharge is prohibited, confirm that holding tank capacity is sufficient for the restricted leg. Plan for shore reception of retained washwater and EGCS residues. |
| Document mode changes and discharge stops | Ensure that the EGCS Record Book records every mode change, discharge suspension and discharge resumption with date, time and position. Position-linked records are essential for the evidence chain. |
| Keep restriction list current | The geographic restriction map is changing. Update the port-by-port restriction list before each voyage rather than relying on a list compiled for a previous voyage. |
The SMART ESM provides the real-time monitoring and continuous data logging that supports the evidence chain for each leg of the voyage, including position-linked records that confirm where discharge was and was not taking place. For marine vessel operators seeking guidance on monitoring system requirements for specific routes, Rivertrace’s technical team can advise on the appropriate monitoring configuration.
What Does the Future of Geographic Restrictions Look Like?
The trend is clearly towards more restrictions, not fewer. The IMO process under MEPC.1/Circ.899 provides Member States with a framework to justify restrictions, and more coastal states are using it. OSPAR Decision 2025/01 creates a binding roadmap for the North-East Atlantic. PPR 13 and the forthcoming PPR 14 are considering further control measures. HELCOM is developing its position for the Baltic.
Operators considering whether to invest in scrubbers, or evaluating whether to retain or remove existing EGCS, need to factor the trajectory of geographic restrictions into the economic case. A scrubber that was economically justified on a route with no restrictions may be less attractive on that route if restrictions are introduced or expanded during the vessel’s operating life.
For a full explanation of how MEPC.340(77) strengthens the compliance documentation requirements for newer EGCS installations, see What Is MEPC.340(77) and How Does It Differ From MEPC.259(68)?.
Frequently Asked Questions
Where is open-loop scrubber discharge banned?
Open-loop scrubber discharge is banned or restricted in 45 countries globally according to OSPAR’s 2025 background documentation, with 13 states or regions prohibiting discharge throughout their territorial waters based on official documentation. Key current restrictions include Singapore port waters, Port of Fujairah, Chinese territorial waters for ships calling Chinese ports, California state waters, Norwegian fjords and specific coastal areas, and parts of the Baltic Sea. OSPAR Decision 2025/01 will extend restrictions across the North-East Atlantic from 2027.
Is open-loop scrubber discharge banned in the North Sea?
Not yet in full. OSPAR Decision 2025/01 requires OSPAR Contracting Parties to prohibit open-loop EGCS discharge in internal waters and port areas by 1 July 2027, and all-mode discharge by 1 July 2029. The North Sea falls within the OSPAR area and ships trading through the North Sea, English Channel and surrounding waters will be subject to these restrictions once national implementing legislation is in place. Some individual North Sea coastal states already have restrictions under national legislation.
Is closed-loop scrubber discharge permitted in all ports?
No. Some jurisdictions restrict or prohibit EGCS discharge in any operating mode, including closed-loop bleed-off. OSPAR Decision 2025/01 explicitly covers discharge in any mode from 2029, meaning both open-loop and closed-loop bleed-off will be prohibited in OSPAR internal waters and port areas. Where bleed-off cannot be discharged, it must be retained onboard and delivered ashore at a reception facility. Operators must check the specific restrictions for each port rather than assuming closed-loop operation is universally unrestricted.
What is the legal basis for port-level discharge bans?
IMO resolution MEPC.1/Circ.899 provides Member States with a risk and impact assessment framework to justify the introduction of restrictions or bans on EGCS discharge in their waters. This is the legal and technical basis for national and port-level controls that go beyond the global IMO parameter-based framework. Regional conventions such as OSPAR and HELCOM also provide a legal basis for stricter measures in their respective geographic areas.
Does meeting the IMO washwater limits permit discharge in Singapore?
No. Singapore prohibits open-loop scrubber discharge in Singapore port waters regardless of whether the washwater meets the IMO parameter limits. A discharge that is fully within the measured criteria is still prohibited if it takes place in waters where discharge is banned. The IMO parameter limits are a necessary but not sufficient condition for compliant discharge.
How should operators prepare for OSPAR Decision 2025/01?
Operators trading regularly through North-East Atlantic waters should assess their options before the 2027 deadline: confirm holding tank capacity for retained washwater during restricted legs; confirm fuel switching arrangements for routes where discharge is prohibited; confirm shore reception availability for washwater and EGCS residues at ports on the route; and review EGCS Record Book procedures for documenting mode changes and discharge stops. The 2027 deadline is less than two years away and operational changes take time to plan and implement.
Is open-loop discharge permitted in international waters?
Open-loop scrubber discharge is generally permitted in international waters outside territorial waters and specific regional jurisdictions, provided the washwater meets the IMO parameter limits under MEPC.259(68) or MEPC.340(77). However, ships transiting the territorial waters of states with discharge bans must stop discharge when entering those waters. IMO PPR 13 and PPR 14 are discussing potential further control measures that could extend restrictions to additional international areas in the future.
| Related content → What Is MEPC.340(77) and How Does It Differ From MEPC.259(68)? → SMART ESM: Washwater Monitor product page → IMO PPR 13: Key Developments in Marine Pollution Prevention |