Water pressure

[Wade Johnson]

The house is a 1960 slab on grade. City water pressure entering the house at 60 PSI. The bathroom sink faucets (hot water side) have normal pressure until the shower faucet is turned on then the sink pressure drops to a trickle. What is the cause of such a reaction?

[H.G. Watson, Sr.]

You seem to be describing a FLOW problem.

Usually its an obstruction. Depends if this is new work/rework or a symptom of old work. Can be an undersized fixture branch, an unsupported or pinched riser, or an obstruction in the shower head, faucet aerator, cartridge, stop valve, etc. A Supply valve somewhere not fully open (stuck not fully opening spinning gate valve is the most common - in this case since you mention hot water I'd first suspect the valve at the cold water side of the water heater - and consider someone has removed a water saving restrictor device from the shower head) Verifying pressure at the water heater drain port and other locations (hose bibs, laundry tubs, etc.) are diagnostic. Failure to flush out new fixtures and mineral deposits are the usual suspects.

Smaller diameter = higher pressure less volume flow; when fixtures requiring greater flow, such as a tub or shower are opened - and should be supplied with a larger branch, pressure is reduced and insufficient flow.

Don't confuse pressure and flow. The "feeling" of pressure at the shower or faucet is often accomplished by aeration.

First "test" is to determine if this is a cold water only, hot water only, or mixed water temperature symptom (example cold water inlet to water heater obstructed or not fully open).

The next bestest test is to verify flow in gallons per minute. This can easily be accomplished with a graduated container (such as a bucket) and and a stop watch. To measure the shower remove the head and measure the output from the shower arm - it should have the same capacity as the tub spout, not the shower head water saver limit (further reduced/restricted).

[Scott Patterson]

With a home of that age, it most likely has galvanized supply lines and they have become restricted by the build up of minerals and rust. Replacing the lines is about the only thing that will cure it.

You could remove all of the aerators to see if they are clogged, but with 40+ year old pipes they are most likely the culprit.

[H.G. Watson, Sr.]

One more possiblitiy I failed to mention.

A point of use anti-scald device at the sink. These aren't as common as thermostatic tempering pressure balancing valves at the shower - but for a while were popular for elderly/children/sensitivity impared retrofits at bathroom sinks.

If you're pulling less than all hot untempered water at the shower and an anti-scald device is at the sink where you are pulling hot water and it reduces to a trickle - this could also explain a shut down to nothing but a trickle at the sink.

[A.D. Miller]

The next bestest test

HG: Just exactly what did you add to your coffee this morning?:D

[H.G. Watson, Sr.]

Nothing but the coffee itself and the company of little children:D . The Grands & greatgrands were up and down all night kept me up (their parents are sleeping in). I cheated and had a cup this A.M. despite having been ordered off the caf months ago by the Docs.

I guess its having its negative effects (plus talking with little children A LOT in the last few hours). I'd probably refer to a WC as a potty if posting this morning on the subject.:o

[A.D. Miller]

I cheated and had a cup this A.M. despite having been ordered off the caf months ago by the Docs.

HG: Understood. I've been ordered down to half-caf. What a drag.


(plus talking with little children A LOT in the last few hours).

HG: That may beat talking with the adults.

[Dom D'Agostino]

I doubt the house still has the original plumbing, being in Central Florida.

The piping may have been done wrong, sometime I find 1/2 inch for the entire hot side, which results in a noticeable flow drop at multiple running fixtures.

Dom.

[john_opwin]

As you said home is too old. It could be problem of supply lines. :rolleyes: