Water Pressure

Inspected a 2 story Colonial last week. During the Master Bath inspection (2nd floor), I opened the faucets on the tub and sink simultaneously and opened the shower faucet at the same time. The water barely dripped from the shower, indicating a pressure issue. I placed my water pressure guage on an outside hose bib and recorded a pressure reading of 37psi. This home is served by a private community water system. I noted in my report that the pressure is below normal, and recommended for the realtors to contact the water company. Their response was 35 psi is their normal presure setting for the entire system.
The copper supply lines to the second floor are 3/4", so there should not be much of a pressure drop to the second floor bathrooms. The 2006 IRC calls for a minimum pressure of 40 psi. I have never had an issue with low pressure on a relatively new home (10 yrs.) serviced by a public system. Any thoughts??

John Evans:)

I would Report water pressure is a little lower then many areas.

Off the record if it was my home and I felt I needed more flow .
I would put in a pump and a storage tank for reserve.
Also I think I have lived with exactly the same thing at a home we had 35 years ago and you soon learn to adapt to what you have .

I am a fanatic on this had the same problem last week also on a large home that had a added on bedroom with full bath. Had the kitchen sink faucet and the washing machine hose running and was not able to get more than a drizzle at the shower head in the added on bath. I made up my own rule to inspect by if you can not have at least two outlets within the home running water and still have volume enough to get a descent shower there is a problem and it will be reported as such I do not want my clients to be surprised by this if I report as a problem and they decide they can live with it its on them not me.

35 psi is as high as many utility companies are required to provide. The issue really isn’t in regards to the pressure, but rather, the volume (as Carley eluded to).

If the supply line from the utility is large enough, 35 psi can deliver a significant volume.

I always note it as such. Some community’s have water towers that simply do not adequately supply sufficient water flow to individual residents. A plumber can simply install a pressure boosting system to improve flow in homes with low pressure.

Yes there is a difference between low pressure and lowflow.
If you have pipes that are a small diameter they will still have good pressure but not enough flow.
You need to check the pipe configuration and see what is wrong that way.
Something could be obstructing also.
Plumber needed most likey since are not responsible to anylize the cause when not sure.
I would just make the above mentioned thoughts on the report and leave it be.

I have found that many systems that have a well supply, whether individual or small private supply, have minor issues especially with low flow shower heads.

Small bits of gravel or rust can get caught in the reducers that are found in the low flow heads. While I would never do it during an inspection, if this happened in my own home (which it has) I would take the shower head off, remove the inner washers and reducers and clean them out. At my mom’s house, they had some pipes replaced and a piece of solder had come off and clogged a valve.

If you are trying to find the reason, before taking the shower head apart, just remove it and see if the flow from the unobstructed pipe is greatly reduced when the other fixtures are turned on.

As I mentioned earlier, the supply lines to the 2nd floor are 3/4" copper, which is standard. Main supply to home is also 3/4" copper. Shower head is OK, sufficient flow when operated independently. Same issues in Hall Bath, cannot operate more than one fixture without losing flow. Oh, the builder of this community owns the water company. You would think that a family could use multiple plumbing fixtures in a $400,000 home!

What size is the supply coming in? and maybe there is a problem at the meter.
Something is restricting flow.

I have seen strange things in My life and it could require a plumber to find out if there is a concern and fix it .
One that come to mind is a Person was mad, jealous or ,upset but there was a washer installed in the coupling that restricted the water flow.
The Pressure was the same with no taps on but when a tap was opened the flow fell drastically .
So write it up move on and it is up to some one else to be the detective .


3/4" I almost missed it too! :mrgreen:


3/4" supply at 37psi should put enough water on the second floor for 1 full bath. The sillcock had 37psi and I’m assuming good flow, so that means there is a restriction inside the house.