According to the Gemara in Hullin on 107a, if there's a vessel with a hole in it, and there's a "stream" (more than a drip but not necessarily the "sheffoferet hannod" required for a real mikveh) connecting the water in the vessel to a kosher mikveh (i.e. a lake), you can dip your hands in the vessel and fulfill Tevilat Yadayim. My question is: can this work with a sink? It can be a great option when you're stuck without a cup available! you can stop the sink, fill it with water, leave the tap running and then dip your hands in it. There are two points I need to clarify for this to work:
A) Assuming the water comes from a reservoir, is a reservoir a kosher mikveh?
B) Is there a constant connection of water from the reservoir to the (cold water) tap, or is it broken at some point along the way?
Also, are there any other potential problems with this solution?