BWMS – Main Types of Challenging Water Conditions

 Under the Ballast Water Management Convention, challenging water conditions are those in which Ballast Water Management Systems (BWMS) may not operate effectively or may face compliance difficulties.

Main Types of Challenging Water Conditions

1️⃣ High Sediment / Turbid Water

• High suspended solids (mud, silt, sand)

• Common in:

  • Rivers

  • Estuaries

  • Shallow ports

👉 Problem:

• Filter clogging

• Reduced UV effectiveness

• Frequent backflushing

2️⃣ Low Salinity / Fresh Water

• Salinity close to 0 PSU

• Common in:

  • Rivers

  • Freshwater ports

👉 Problem:

• Electrochlorination systems become ineffective

• Insufficient disinfectant generation

3️⃣ Cold Water (Low Temperature)

• Arctic or cold regions

👉 Problem:

• Reduced biological activity (treatment validation issues)

• Slower chemical reactions

• Reduced UV transmission efficiency

4️⃣ High Organic Matter

• Algae, plankton, debris

• Eutrophic waters

👉 Problem:

• Increased UV absorption

• Higher chemical demand

• Reduced treatment efficiency

5️⃣ Low UV Transmittance (UVT)

• Dark or muddy water

👉 Problem:

• UV systems cannot deliver required dose

• Leads to non-compliance risk

6️⃣ Ice-Influenced / Seasonal Water

• Presence of ice or meltwater

👉 Problem:

• Mechanical damage to filters

• Unstable operating parameters

 IMO Terms

IMO refers to this as:

Challenging Water Quality (CWQ)

Ships must:

• Follow manufacturer’s operating guidance

• Record actions in Ballast Water Record Book

• Apply contingency measures if BWMS performance is affected