Sometimes you see something just so...Wizard! - you wonder why this hasn't shown up before. In my recent 12 part manual for a DIY Disaster kit, I note that field hygiene, or lack there of, has killed more people in the world than battlefield fighting. Hand washing is a big part of field hygiene - esp if you are using an outdoor Loo (latrine, slit trench or pit toilet.)... The video linked at the top shows how to build a 5 gallon hand washing sink with integrated fresh water storage and gray water catchment. With a pump. In a word - simply Wizard. Total cost in minimal, convenience is maximal and the boon is even little kiddos can easily wash their hands after using the toilet, before eating and so on. Disposal of gray water can be down the same pit toilet used or some distance from the camp. It doesn't take much of a leap to see this 'system' could be incorporated into a camp table used for food prep and wash-up. The same would apply for home use where running water may be problematic.
Part of the genius in this design is that you have to use the foot pump. It prevents wasting water and it makes it completely hands free.
And pretty much kiddo-proof. Nobody is going to (they can't) leave a tap running while they wash their hands. I see this as the big plus when camping with kiddos.
Very clever idea but it can be simplified further by eliminating the dirty water tank. Why not just let it run onto the ground? When the tank fills up you'll either toss it out (which is the same as letting it run onto the ground on the first place) or lug it out of camp and dispose of it in the public sewer system (which no one will bother to do).
I specifically noted the gray water could go to the pit toilet. Disposal of gray and wash water (which may contain bits of food) pose serious health hazards in the long run if not disposed of properly. In my 12 part DIY Disaster kit posting I speak to making and using a French drain if a pit or vault toilet isn't available. I've used campsite where prior users dumped wash and gray water just off the side, or let it run thru the campsite. That draws bugs and can be a bear attractant.
This is a cool idea. I do think kids would love the pump and can picture mine wasting water while "checking it out". Good idea on the water collection. I am usually in sandals or bare-feet in the summer and walking around in mud and waste water would not be good.