I have this Fynspray in the head, it is kind of annoying because there is a ball inside as a valve and it is noisy when pumping it. Also, try to wash your hands when using one hand to pump. There are ways around this, by using a small bowl as a basin.
http://www.defender.com/product.jsp?path=-1|51|299222|316451&id=199032
I have a Whale footpump in the galley but it is very old and started to leak. I thought about rebuilding it but it is just too old, it would be better to just get a new one. My water tank is also early 1970's, last time I washed it out in 2002 got a lot of brown stuff out of it, yuck, what I really need to do is to get a couple of flexible bags, maybe two 20 gallon bags, or maybe even bigger than that. I have tons of room in the "aft cabin" aka sail locker now that the inboard has been removed.