On this trip we have two new couples to bareboat sailing and from the first trip we did, I know that people use way too much water because they are used to “just turning it on.” On our first trip we ran out of water on day 3 on a 44′ Catamaran. While it’s possible that the charter company didn’t fill it up all the way, likely we used it all on showers and washing dishes.
Water while you are sailing is just like diesel/gas.. you have a limited supply and you pay by the gallon (or liter). Don’t expect to find places to buy water that easily either. Not every marina that sells fuel will also sell water.
Your best bet is to take very few showers like you would if you were camping. Use the saltwater as much as possible without putting a whole bunch of soap in the water. If you can, use something that is biodegradable. Usually there is a spigot for salt water for your sink too, so you can use that for part of your washing process.
I think it’s fun to have some shampoo on the stairs on the back of the cat for when you get out of the ocean from swimming. You can sit in the warm sun, use the spray hose that is usually on the stairs and basically take a shower using minimal water.
If you are super lucky (we were this time), you have a watermaker. It is a Desalination process that takes a couple of hours to regenerate your tanks. It takes running the diesel generator, but it was certainly worth it for us. We ended up running this daily because of how much water we were using.