Do Not Drink Sign

Do Not Drink Sign

A do not drink sign is fitted at taps, hose connections, and access points on a vessel’s non-potable water systems to warn crew that the water supplied there is unsafe to consume, even though it may look identical to drinking water at the tap. This pictogram is typically mounted on ballast, cooling, deck-wash, and fire-main connections, as well as any tank or line carrying water drawn from the sea, treated with chemicals, or otherwise unfit for human consumption, preventing a crew member from mistaking a technical water source for the vessel’s potable supply during routine tank or line work.

The pictogram shows a black silhouette of a hand under a dripping tap or a drinking glass, struck through by the red diagonal bar and red circle of the ISO 7010 prohibition family, with no wording needed to convey the warning. This do not drink sign carries IMPA code 33.8550 and ISSA code 47.585.50, the maritime catalogue references ship chandlers and marine safety suppliers use to source the correct pictogram for potable-water risk points during a new-build fit-out or a tank system upgrade.

Marking Non-Potable Water Points Aboard

Ballast tanks, cooling water systems, deck-wash lines, and any tank previously used to carry chemicals or non-food-grade liquids are common fitting points for this sign, since these systems often share similar-looking piping and valve fittings with a vessel’s freshwater network. It is also fitted at test points and sample cocks used during water treatment plant maintenance, where a technician drawing a sample could otherwise assume the outlet is safe to taste. Vessels reviewing our full range of prohibition signs for a tank inspection often order this do not drink sign in quantity to cover every non-potable outlet identified during a class survey.

Produced on fire-retardant material rated for the damp, frequently washed-down conditions typical of tank rooms, pump rooms, and deck areas, the sign resists the corrosive effects of salt spray and cleaning chemicals that would degrade lower-grade printed signage within months. UV-stable inks keep the black pictogram sharp under direct weather-deck sun, an important quality given how many non-potable outlets are located in exposed exterior positions rather than sheltered interior spaces. The material also tolerates the temperature swings found around pump rooms and engine casings without the print cracking or the backing losing its grip.

The sign is available in self-adhesive vinyl for pipework and valve housings and rigid panel for bulkhead or deck-stand mounting near tank access points. Ordering by IMPA 33.8550 or ISSA 47.585.50 lets a chief engineer specify this exact pictogram when updating tank marking during a dry-docking, without needing to describe the non-potable water hazard in words. A compact size suits individual valve tags, while a larger panel format is better suited to marking a tank access hatch or a whole pump room entrance.

Supporting Safe Drinking Water Practices Onboard

Guidance on managing workplace health hazards, including contamination risks from cross-connected water systems, is addressed in general terms by bodies such as Safe Work Australia, and the ISO 7010 pictogram this sign is built from gives vessels a consistent, language-independent way to mark the boundary between potable and non-potable supply. Fitting the same do not drink sign at every non-potable outlet across a fleet reduces the chance that a newly joined engineer misreads an unfamiliar tank system during handover. It also supports the vessel’s own water safety plan documentation, giving inspectors a physical match to what the plan describes on paper.

During ballast or bunkering operations, crew frequently work near multiple pipe runs at once, and a clearly marked do not drink sign at each non-potable connection point means nobody needs to trace piping diagrams back to source before deciding whether a tap is safe to use. This is particularly relevant on older vessels where freshwater and ballast lines were installed close together, making a fitted pictogram far more reliable in the moment than relying on crew memory of a system that may have been modified more than once since the vessel was built. A quick visual check before drawing any sample also protects visiting technicians and surveyors who may not know the vessel’s piping history at all.