Water pressure question

I’m looking to increase my general plumbing knowledge here to better help me understand water pressure issues. I already know this is an easy referral to a plumber.
I inspected a 113 year old home yesterday with 100-105 PSI pressure when tested at the hose bib at the main water entry pipe.
The water pressure at the bathroom sinks, showers, and toilets were all mariginal at best and poor when multiple fixtures were turned on.
In the crawlspace I found that the house was repiped with Pex in the crawlspace that was improperly secured to the floor joists resulting in major sagging. I’ll attach a couple images, unfortunately the qualifity is poor as my camera flash malfunctioned.
Question: would the sagging affect the water flow? I would think yes. Thank you for the imput.
Crawlspace (11)
Crawlspace (14)

the sagging would not effect water flow or pressure. was entire house re-piped? or just a few fixtures.
any pressure over 80PSI is way too high, can cause pipes to burst and those push fitting to pop off pipe.
if every pipe was replaced with pix and water pressure is that high, there needs a pressure regularor installed on the Main right after shut off valve, and also a expansion tank installed at the water heater.

flow issues with bathroom can be old galvanized pipes still in use , clogged with rust. aerators clogged with debris, could be a number of things causing flow issues.


Some of the original galvanised piping was in place from the main to the water heater. I know that may affect it. All fixtures were newly replaced and appeared to be brand new. Pressure regulator was installed and I’m guessing it’s no longer working.

There’s your problem, at least part of it. The sagging PEX is not an issue.

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No, but as indicated galvanized pipe would.

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The sagging lines are a impeding deficit that can turn into an adverse condition. The installation is highly suspect.
You think there galvanized lines hidden in the walls?
Call it out…
Recommend: A licensed plumbing contractor: 1: assess poor water flow. 2: Support sagging domestic potable water plumbing lines.

Sagging lines: No!

Sagging lines: Yes!

I love this forum!! :joy: :stuck_out_tongue:


That may be true but will not have any effect of the water pressure/ volume / flow.


Jeff, I think your comparing apples to oranges. You measured water pressure (psi) at the hose bib, and you observed water flow rate (gpm) at the inside fixtures. Check out this YouTube explanation:


I get what you’re saying Randy, I was trying to give the forum as much info as possible to try and get an answer that makes sense.

Jeff Bissonnette
SVP, Risk Management, Certified Inspector
JDB Property Inspectors, LLC
18543 Yorba Linda Blvd, #125
Yorba Linda, CA 92886
O: 866.954.6770
C: 714.747.6351


A Proud Contributor to the Wounded Warrior Project

“We inspect all homes as if they were ours”

Jeff, if you want the above to be at the bottom of every post that you make, effortlessly.

Do This:

SIGNATURE: Click on your face in the upper right hand corner of this page. Then click on the bell. Then click on preferences. Then click on profile and scroll down to signature and fill out the information that you want to appear under every post that you make. AND LAST, scroll to the bottom of the page and click SAVE CHANGES.

What caught my eye, the poor domestic potable water PEX installation, SharkBite connectors and no manifold. Opinion, that is a DIY domestic potable water line installation.
How to Minimize Pressure Drops in PEX Plumbing Systems.

The house was a so called “flip”, need I say more about some of the work quality.


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Thank you sir.