Water pressure and supply question.

[oldhouse]

My new (very old) house has an interesting occurance when you turn on the water. In any faucet or other fixture in the house, when you turn on the water you get what I would call 'great' water pressure. It lasts for about 2-3 seconds, then goes down to what I would call 'fair to good.'
Overall, my pressure is fine for showering and such. I just wondered why the difference.
Of note, and I don't know how this may play into the issue, but....
The house is significantly higher than street level (where the water main is) and a good distance back from the street. A rise of ~30-40' over about 250'.

In addition, at some point, the main supply to the house was replaced (it was likely the orginal lead prior). The new 'main' coming into the house is only 1/2" copper!!!

Anyway, just thought I'd hear what you all have to say about that. Thanks,
Quinn

[Cass]

I doubt it was replaced.

It would be a minimum of 3/4" and more likely 1" or more for that distance. My guess is that the line broke outside the foundation and some DIYer or the home owner made their own repair using 1/2" copper rather than replacing the whole line due to the cost. On top of that your original line is most likely galvanized steel that has coroded inside the line so the pressure is reduced because of that. This is just a guess.

No plumber worth anything would use 1/2" to feed a house or repair a line unless it was 1/2" to start with which I highly doubt.

[jimbo]

A defective pressue regulator can cause symptoms as you described. Get a $10 gauge from a hardware store and attach to a hose bibb or washing machine valve. Check the pressure with no water faucets running, Then turn on the tub or shower, and see how much the pressure drops. SO drop is normal, but excessive drop can be a bad PRV

[oldhouse]

My guess is that the line broke outside the foundation and some DIYer or the home owner made their own repair using 1/2" copper rather than replacing the whole line due to the cost.

That's probably about right. Especially given the work I found upstairs in the house in an area that they decided to build a 'new bathroom.' I have ripped it all out and am installing an entire new bath- this time with appropriate venting and such.

I'll have to check the pressure with a guage.
Thanks,
Quinn