Back at the boat I siphoned the water out of our redundant 600 litre tank directly into the bilge thus getting rid of our port list that we had carried ever since Oxelosund where the overzealous boat yard had filled the wrong tank. We had also had a recurring problem with the toilet whereby it would, intermittently, refuse to prime. I had dismantled it, cleaned and oiled it on several occasions only to find that it would work a few times and then fail. Eventually I hit upon the idea of gluing a couple of washers to the clean water outlet valve to “encourage” it to close more effectively. Thus far a bit of araldite and a couple of stainless washers appear to have done the trick so we are keeping our fingers crossed.