Compressed Co2 Pressurized Water

[nimblemotors]

In my boat build planning, I've been thinking about plumbing.
The plan for a toilet is compost, so no water needed there,
but the bathroom sink, and the kitchen sink will need some water.

I'd like it to be real simple. One thought is to just use gravity, but that means the heavy water is above not below, so don't like that.
What I'm thinking is using a tank of compressed c02 to pressurized a 5 gallon tank of water under the sink, which could be refilled from a larger tank using compressed c02 to force it into the smaller tank.
I like the idea of no pumps to fail, electric or manual.

I have a soda fountain setup, and this is essentially how it works (but it carbonates too which I don't want). A have 3 of the 5 Gallon Cornelius Kegs,
and a couple aluminum c02 tanks. I'd probably get the lighter carbon fiber tanks to save weight.

My questions are does anyone do this?
How long would 5 gallons last in a kitchen faucet?