Whether it’s elevated bacteria levels, incorrect chlorine values or missing documentation, a failed water inspection means action is needed. But what exactly should you do when your ship’s water test doesn’t meet the mark? And how can you make sure you’re not caught off guard next time?
Common reasons for failed ship water tests
Most shipowners understand the importance of safe drinking water. Nevertheless, water system contamination is more common than you might expect. Failures often arise from seemingly minor issues: a wrongly stored sample, a forgotten logbook entry or a shower that hasn’t been flushed in weeks. Here’s some of the most common reasons for failed water tests on ships:
- Incorrect on-site values
Parameters like free chlorine, temperature, pH, turbidity and conductivity need to be measured at the moment of sampling, instead of later in the lab. These values can shift during transport, so failing to record them on site makes the sample harder to interpret, and may lead to rejection by the inspection authority. - Microbiological contamination
One of the most common reasons for failed water tests is bacterial growth. Coliforms, E. coli or Legionella can develop when water stagnates, temperatures fluctuate, or disinfection levels drop, especially in dead legs or rarely used outlets. Even a single positive result requires follow-up action and often retesting. - Incomplete or missing documentation
A technically correct test can still be rejected if reporting isn’t in order. Missing data (such as date, sampling point or IMO number), lack of chain-of-custody forms or unclear lab methods can make the result inadmissible during inspection. - Non-representative sampling
If a water sample is taken only at the tank, it won’t reflect water quality where it’s actually used. According to WHO guidelines, both source and outlet points should be tested – especially at the furthest point of use, where temperature, pressure and disinfectant levels are most likely to diverge. - Non-compliant testing parameters
Not all labs apply the correct parameters for maritime environments. Some rely on land-based drinking water standards, or skip key flag state-specific requirements such as turbidity or E. coli testing. Even when results look good, these mismatches can lead to dismissal of the entire report during inspection.
Also read: Marine water sampling: requirement or opportunity?
Failed water inspection? Here’s how to respond.
A failed on-board water test can affect your Ship Sanitation Certificate and potentially delay operations. It can happen to the best of us, but you do need a plan. Here’s how to respond effectively and in line with international health regulations:
- Assess the report carefully
Identify what exactly caused the failure. Was it a microbiological exceedance, a reporting issue or procedural oversight? - Isolate potential risks
If contamination is suspected, restrict use of affected outlets (especially showers, medical taps, and galleys) until retesting is complete. - Document immediate measures
Whether you flush, disinfect or install filters; document your action. This is essential for port state follow-ups. - Initiate corrective action
This may include thermal disinfection, shock chlorination or even pipe replacement. Base your action plan on the specific issue found and ensure it aligns with flag state procedures. - Consult with a qualified sampling provider
Work with a maritime water expert who understands your flag state’s requirements. A specialised provider helps you choose the right test parameters, ensures accurate documentation and avoids miscommunication with inspection authorities. Make sure the lab they work with is certified and familiar with maritime standards, so you can be sure the sampling process is performed correctly. - Retest and keep records
Retesting must follow the same procedures and should be done under expert supervision. Ensure all corrective steps are recorded and added to your ship’s sanitation log.
Long-term prevention: turning failure into improvement
A failed inspection is disruptive, but it can also be a valuable moment to improve your process. Review how your sampling is organized. Are the sampling points correct? Are temperature and chlorine checked on-site? Do your reports match the flag state’s requirements and are you testing regularly?
Marine water testing is too important to leave to chance. Whether you need fast retesting or a full compliance review, make sure you’re working with people who understand the system, as well as the maritime industry.
Want to know more about how to prepare for your on board water sampling? Read The impact of the WHO Guide to Ship Sanitation on water sampling or learn about our marine water sampling services.
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