Started about 1 month ago. Step into shower and after a minute, the water pressure drops off. Turn off water in shower and wait and pressure returns. I am on city water, measured a couple of years ago was @ 85 psi Began to troubleshoot and here is what I did so far.
All faucets suffer during the drop off
3 outside hose bibs, only 2 suffer the drop off, third one no change.
I have a water softner and a whole house sediment filter. Changed the filter out, no difference. Bypassed the water softner and filter no difference.
Drained the water heater, no residue. Shut off the cold water going into the water heater. All fauctes etc now have no water flow with one exception, one outside hose bib. (apparently 2 outside hose bibs are being fed thru the water softner???) Been in this house since new 20 yrs ago.

Looking for suggestions what to do next? Will attempt to rig a pressure meter some where??? Tx

 

Check all the faucet aerators?

Install a pressure gauge somewhere near where water enters house, run the water to point it drops then check pressure, would tell you if it's internal (no pressure drop) or external (pressure drop)?

 

If one outside faucet always works fine and is before the softener...... that pretty much points to your softener circuit.... not incoming water pressure.

 

The circuitry is from source to a valve 3/4" (bypass) being closed and another valve (before the bypass valve) that is open routing water thru filter then WS then to another valve (after the bypass valve) back to house supply. All water goes thru Filter & WS. When I bypass, I close valve leading to filter and WS and close the valve from the filter and WS. I then open the bypass valve to the house. The filter and WS is no longer in the circuit. I have had this configuration since Oct 2010. Even though it may be all aerators, I see that as a slim chance?

One possibility, my city usage meter has not worked for 6 months or more. I have called and got a work order for the fix but no one has showed up yet to fix it. City says due to covid and shortage of workers is the reason. Wonder if that could be the cause. When it warms up a little, may go to the curb, dig out the valve and exercise it a bit??? Tx for the help so far. )

 

As long as you have something in the house.... the single bib.... that always works fine..... the problem is not outside the house in the supply.

 

Pete, I agree with you on that. I not sure why one bib is apparently plumbed straight from the source water supply and the other 2 are not?, don't know if that is standard plumbing practice. All my pvc piping is in a slab.
I should also add, that I do not use (even thought it is installed) the factory bypass valve on the WS. I made an external bypass system when I installed the sediment filter to ease change out of the filter/housing etc.

 

That is a personal preference, I have one hose bib, in the garage, that is soft water for washing cars, all the others, presumably for watering grass/plants that are hard water so that it doesn't drain the capacity of the softener when someone leaves the sprinkler on all day!

 

Maybe there is an underground leak. Sounds like you haven’t gotten a water bill recently.

 

I have a problem believing it's a valve or blockage since the pressure is good for a full minute before decreasing. When there's a faulty valve or similar, you'll get good pressure for a second or two, and it will drop.

Do you know if there's a PRV at meter? Doesn't make total sense if one outdoor bib is working as expected, but I wouldn't rule it out as they can fail in odd ways.

 

I get a water bill every month, however it is the exact low amount in $ and gallons used. As far as the PRV, I am unaware of one. From the main city water pipe, it is first routed to the water meter. Out of the water meter there is a "T" connecting to the house supply and the other side to a back flow device for irrigation use.

Zorfdt: agree with you, I just can't get my head around what is happening. The low pressure bib's, when I water flowers etc using a hose, pressure is great for a minute or so and then slowly depressurizes that maybe it drops to about 10 feet of range, full pressure can go 20+ feet or more. I removed the sprayer heads and just had an open hose, and it to decreased in pressure. Nothing else in the house is using water at that time Puzzling for sure.