Fresh water consumption 1

[iceland1]

Hi, Does anyone have norms for fresh water consumption (per person, per day) for marine/shipboard applications. In patricular for an FPSO but any vessel type would appreciated.

 

[oxilume]

Iceland 1,

Use 30 gpd/person.

 

[iceland1]

Thanks oxilume, do you inculde water for showering, black and grey water, water for lanundry and galley/cooking use in this estimate?

 

[ktm5]

iceland1,
In my experience aboard tankers with a crew of 22 persons, 10-12 tons per day was average. This equates to about 145 gpd/person all-in.
rgds, ktm5

 

[oxilume]

iceland1,

ktm5's 145 gpd is extremely high for a marine application. Why? US EPA uses a figure of 100 gpd per person for designing a wastewater plant. And this number is conservative.

The US Navy uses 30 gpd. Of course the Navy is frugal with water since a Navy vessel has a much larger manning than a merchant ship.

For example, a Spruance Class destroyer has 2 two stage flash type evaporators rated at 8,000 gallons per day each. The manning on a Spruance Class destroyer is 300. However, some DDGs, Cruisers and Destroyers may increase manning to 350.

If the evaporators are working perfectly, then that would be about 53.3 gpd per person. However, you must keep in mind that the evaporators also produce makeup water for the boilers. So that leaves less potable water for drinking, cooking, showering, cleaning, etc.

 

[ktm5]

iceland1,
oxilume may be correct for Navy application where there is tighter control over water consumption. My experience comes from deep sea applications aboard commercial tankers and bulk carriers. I believe an FPSO may have similar consumption with crew personal use, washdown and cleaning applications, drinking water, near-constant galley utilization, boiler water testing, plus other machinery fresh water needs. The largest components were the washdown and cleaning and machinery use. Maybe you could make an allowance for these non-personal categories and then add on oxilume's figure per person. My feeling is to have a comfortable safety margin in the design, rather than need a retrofit right out of the box.
rgds, ktm5

 

[oxilume]

iceland1,

Here is your rule of thumb figure;

Use 100 gpd/person for potable water consumption
Add boiler/water feedwater makeup if you have boilers onboard
Add water washdown water consumption

This will probably bring you close to KTM5's 145 gpd per person.