A number of sailors have been taken to hospital after an issue with the freshwater system onboard HMS Portland.
It is being reported that the Royal Navy ship's supply had become contaminated.
HMS Portland has now returned to her base in Portsmouth as a precautionary measure and HMS Richmond has been stood up to cover any contingencies.
A spokesperson for the MOD confirmed this morning that "nearly all involved have been discharged from hospital" and that "all are expected to make a full recovery".
It said that a "thorough investigation will take place" and that it will "review processes to ensure this does not happen again".
Most recently the Type 23 Frigate has spent time alongside warships from Germany and Poland as part of the Standing Nato Maritime Group One.
Last month the vessel was involved in monitoring a Russian-guided missile frigate and accompanying tanker as they sailed in international waters near the UK.