Fresh Water

Question 1

Fresh water testing, What are we looking for? Maintenance?

Answer 1

Every week we take a water sample from a different source, this is in house. We look at:
- Water temp
- pH Level
- TDS
- Hardness

Every 3 months we have a chemist onboard who takes three samples from around the vessel and will test in the lab. Looking for bacteria and viruses

Question 2

Superchlorination, why, how often and the procedure?

Answer 2

It is done to disinfect and sanitise our water system. We carry this out yearly and every 6 months on our bunker water hose.

Our shipboard procedure is to have our tanks at 50%, we inform all crew in advance so we are able to go get bottled water.

We shut down equipment where we don’t want chlorine such as steam humidifiers, Galley oven, Dishwashers, drink water filters, boilers.

With the correct PPE we will calculate the dose for 50ppm in each tank and add to tank. We will then go round and run every water source, taps and showers till we are confident chlorine is in the pipework. We let this sit for 12 hrs minimum.

Then we add a neutraliser to remove the chlorine and again flush the system. We take make multiple tests around the vessel to ensure it is chlorine is at a good level.

Now we bring system back online and inform crew are able to use again

Question 3

Fresh water dosing and types?

Answer 3

• Silver ion, this disinfects the water as it passes over the ions
• UV Steriliser, this disinfects water by disrupting the DNA of microorganisms and bacteria in the water.

Question 4

What tank maintenance does MGN 525 refer to?

Answer 4

• Every 6 months water shall be changed
• Every 12 month tanks opened, ventilated, inspected and chlorinated
• Every 5 years tanks to be pressure tested

Question 5

What are the maximum and minimum levels of silver ion and chlorine in water tanks? How do you test it?

Answer 5

Silver ion max is 0.1mg/l and no min

Chlorine is 0.2 to 4.0mg/l

We have a portable meter that can be placed in a beaker and take readings of everything

Question 6

How would you know that the dock water is portable?

Answer 6

I always come into ported full, so on arrival or even before I would discuss with the agent the water situation.

We have a very advance water bunkering system called spot zero, it’s pretty much reverse osmosis, I would run it through this and complete a water test with the ships equipment while it discharges overboard. If not I would get it tested externally

Question 7

Where would you find guidelines for super chlorination?

Answer 7

MGN 525