I'm not 100% sure on the diagram, but I believe I see 3 problems with this.
1. High pressure. Most blocks are not designed to work with mains-like water pressures. Sure you can use high-pressure tolerant tubing but the blocks will bulge out and the plastics could crack.'
2. I don't see a pump in your diagram, which implies you are using the flow from the mains to maintain coolant flow. If you have nothing in your house using water, your coolant will stagnate inside your blocks, causing temperatures to skyrocket within seconds, easily boiling the water inside and, again, causing pressure/bulging problems and potentially causing your blocks or tubes to explode.
3. You are using city water, which has a lot of additives. This can cause a lot of buildup and corrosion within your blocks. You probably won't need to worry about microbes, but the chemical reactions and battery-like reactions (You don't know what other metals are used in your city water lines) will eat away at the metals in your loop.
I don't see this being a viable liquid cooling solution.
If the aim of this was to have a noiseless PC, do what I do. Use standard liquid cooling components, but instead of having the fans/pump/other noise-making parts in the PC, run long coolant tubes to another room, or outside, where you can't hear it. If you choose to run them outside, make sure to use a coolant that's tolerant of sub-zero temperatures. In dry environments (<20% humidity), I don't foresee condensation being a critical problem. My ambient is 21C and 17% relative humidity, with outside ambients at -8C. My components surface temperatures is 3C and not getting any condensation. Any significantly lower and they'd be freezing any posible condensation
(Yes, I live 'dangerously')
(Yes, I know, I don't have my SLI bridge attached)Edited by ssateneth - 1/1/16 at 4:42pm