Pretty sure the idea of "Holy Water" is just water that has been "blessed" by a Priest or Pastor, typically for purposes of Baptism. It's essentially water dedicated for Baptism.
Some churches leave it in it's container constantly which during various outbreaks (like swine flu etc) raised concerns for many people because of a fear of infection. I find it interesting that "studies" have been done to test "holy water" from various churches to see if it contained bacteria.... the answer of course was a huge affirmative yes... like did they seriously expect any other result? Sorry, It was just one of those eyebrow raising moments for me that people would assume that somehow a standing pool of "holy water" would someone be different bacteria wise than any other standing pool of water.
Haven't ever experienced a foot washing. Actually this is the first time I'm hearing of it, and I currently attend a UMC church.
The church I attend does something every once in awhile that baffles me. We have a service almost identical to communion, but instead of using wine/grape juice they use plain old water.... They call it something like a friendship or fellowship service.