Reply #10: What kind of valves did he install?

[Wash. state Desk Jet]

Ask the contractor if he installed safety shut off valves. All house plumping is half inch to location.3/4 inch is reduced down to 1/2 inch for feed. Water tank requires a 3/4 inch feeder line,

Replacing water lines will increase water pressure, if you have any old pipe around ,look inside there with a flash light , than you will understand the increase of water pressure. Lines from valve to faucet are commonly 3/8 inch fitting. The coupling at the faucet end is 1/2 inch on the inside diameter to connect up to the facut hot and cold feed..

What you might try is removing the aerator from the sink faucet ,than run the water full bore and see what happens. Use pliers to remove aerator.

That will flush out the inside of the faucet. It will also clear the stuff out of the water lines. Perhaps the contractor forgot to flush out the lines.

Rinse out the aerator before you replace it. Little particles sand like accumulate and cause blockage. Did the contractor install air hammers?

And your faucet ,ask your contractor about that. Some have safty pressure regulators built in.Some also have hot water tempture regulators as well. Mostly tub and shower facuts . Rather a child protection thing.