Since day one QE2 ALWAYS had a water problem. At launch they had 3 flash evaporators that basically boiled water and condensed the steam. Supposedly these supplied 1200 tons of water/day......not.
The evaporators also had to supply make up water for the boilers. We are talking a different quality of water here. Boiler water had to be basically 99.99% distilled, in laymans terms, while drinking water needed to be much less pure. The 1200 tons/day also reflects on optimum conditions, does not take into account the Engineers party the night before...did I say that?
The sea temperature, the quality of the steam being delivered from the boiler room, the cleanliness of the plant...mussels seaweed, fish, that can reduce the efficiency of the plant. On a GOOD day with everything operating correctly, the tea boiler shut off, and the bench vise closed (in joke there Beardy rich should get it) the evaporators would make 1000 tons/day. Domestic consumption, showers cooking LAUNDRY would take about 800 tons, boilers would take about 400. So we are already on a negative.
We would buy water almost any where for the domestic, just to make up the negative. This was bought on board into holding tanks, then treated with chloros/bleach then sent around the ship. If however we went to a place where a health warning was issued for..it was no thanks! Water was treated to WHO standards, which are the same as most US/UK cities, records were/are kept and examined by every health authority that had jurisdiction. That is regarding bacteria! Some of the water we bought varied as to taste because of where it came from. NY water tastes different from LA water, Soton water tasted different from Edinburgh water. But it was all safe.