Thanks.

Looking up the exact figures, 1 atmosphere is 14.7 lbs/sq in, and 1 atm pressure is exerted by sea water at 32 ft below the surface. (It varies slightly in fresh water, due to the different density).

You always have to take into account normal atmospheric pressure at earth's surace when dealing with these kinds of problems, so I assume when you say tap water comes out at 50 psi, I assume you mean 50 psi ABOVE atmospheric pressure. In other words, in airless space, your faucet would be operating at 64.7 psi. Likewise the pressure under 32 feet of sea water is actually 29.4 psi, taking into account the added weight of atmosphere above the ocean. Pressure is always meansured against some standard, and that standard is 1 atm on earth.

Since the weight of the atmosphere affects your faucet pressure in exactly the same way it affects the sea, we can ignore it, so the depth at which ocean pressure exactly balances your 50 psi faucet is 50/14.7 x 32 = 108.84 feet. Any deeper and the pressure will force water up into your faucet.