Diagnose water pressure/flow issue

[daveg01]

I was hoping someone could help me diagnose a water pressure/flow issue I have in my house. We have sub-optimal water flow in the showers and it drops considerably when we turn on other fixtures. The house is 2 stories with a basement. It is a mix of galvanized and copper and the main coming in from the city is copper.

I ran a few tests.
1. 3rd floor bathtub = 8 quarts/minute
2. 3rd floor sink = 4 quarts/minute
3. 3rd floor sink = 40lbs
4. 3rd floor sink = 5lbs when tub valve is open
5. 3rd floor sink = 2 quarts/minute when tub valve is open
6. 3rd floor tub = 5 quarts/minute when faucet is on
7. 3rd floor tub and sink are bone dry when basement laundry sink is wide open
8. Basement laundry sink = 8 quarts/minute
9. Kitchen sink (1st floor, above laundry sink) = 4 quarts/minute

Is this enough information to point us in the right direction?

Any help would be appreciated.

Thanks

 

[Cfinn]

I would suspect that the internal diameter or the pipes is full of corrosion where the copper meets the galvanized plumbing. Esp if it’s old galvanized.

Otherwise pipes are undersized. Are they 3/4 inch lines coming up threw the floors?

 

[daveg01]

I will measure the size of the copper tonight. I will also try to map it all out so I understand what branches off of what. Is there a chance that the city is only providing me with 8 quarts/minute?

 

[Cfinn]

Not in any city I know of.

 

[daveg01]

I mapped out the plumbing the best I could. I have 3/4" for must of it, but it drops to 1/2 when it feeds the fixtures (shower, sink).

I attached photos of the pluming map and some photos to provide more context.

 

[TomFOhio]

If the problem happened all of a sudden I would call the water dept and have them check the pressure for you at the meter to be sure everything is ok there. Maybe a bad meter.

 

[daveg01]

I think it has been like this a long time. We recently moved in, but I am pretty sure it's been this way.

I was thinking about testing the flow at the exterior outlet that is near the main. That should tell me what the system capacity is, correct?

 

[TomFOhio]

I think it has been like this a long time. We recently moved in, but I am pretty sure it's been this way.

I was thinking about testing the flow at the exterior outlet that is near the main. That should tell me what the system capacity is, correct?

Yes & Around here the water pressure coming into the house from the city is between 50 - 55 Pounds.

 

[daveg01]

So I ended up replacing my main shutoff and we tested the water pressure and flow delivered from the city.

Meter: 48PSI and 3.5GMP
3rd floor bath: 40PSI and 1.25 GMP
Basement laundry sink: 45 PSI and 2 GMP

The 3rd floor goes dry when you turn on the laundry sink.

I have a mix of galvanized and copper. Most of the galvanized can be accessed in the basements dropped ceiling.

My contractor is suggesting that I install a booster pump because he has seen it work well at a different locations.

Does this seem like the correct first step?

If so, could somone please recommend a good quality booster pump? He was suggesting one built by "Franklin Electric".


Thanks

 

[Diehard]

What is the static pressure at the meter. (No flow pressure.)

What is that you're showing at the main?



I assume that 3.5 gpm at 48 psi was just after the meter?

Looks like you may have a restriction somewhere upstream of your test at the meter. You should be getting much more flow then what you are getting, at that pressure and through a 3/4" or a 1/2" pipe.

Do you have a neighbor where you can test their flow vs pressure at their meter or even a nearby spigot if they have one.

 

[daveg01]

Static Pressure at the main is 48psi.

The notation on the diagram says "outside". It refers to an exterior spigot.

I have sense added and additional valve right off the main that goes to a garden hose fitting. That is where I tested static pressure.

I have been reading up on how to diagnose pressure/flow issues on residential properties. It is not clear to me if a booster will help much with my supply/flow issues since I already have 48lbs of static pressure at the meter and 40lbs of static pressure at the furthest/highest outlet.

The project starts Friday, I am leaning towards replacing all the galvanized we can get to without significant demo. Any suggestions or guidance would be appreciated.

 

[Diehard]

Static Pressure at the main is 48psi.

The notation on the diagram says "outside". It refers to an exterior spigot.

I have sense added and additional valve right off the main that goes to a garden hose fitting. That is where I tested static pressure.

I have been reading up on how to diagnose pressure/flow issues on residential properties. It is not clear to me if a booster will help much with my supply/flow issues since I already have 48lbs of static pressure at the meter and 40lbs of static pressure at the furthest/highest outlet.

The project starts Friday, I am leaning towards replacing all the galvanized we can get to without significant demo. Any suggestions or guidance would be appreciated.

 

[Diehard]

The 40 psi static pressure at the highest point(furthest doesn't matter for static pressure) is simply telling you it's 18.5 feet higher in elevation then 48 psi location. 8 psi difference x 2.31 ft/psi = 18.5 ft.
There is something restricting the flow BEFORE you flow through you house piping. Granted your old piping would have an impact on flow vs pressure but in this case you could change it to 2" throughout (Exaggerating) and never do better than what your getting near the meter.

Contact your water department tell them your not getting any flow(2.5 gpm max.) from x number of feet after the meter.

Where was your gauge when you were flowing the 2.5 gpm from the spigot? I took your previous statements of pressure and flow as the pressure while you were flowing that amount. What is called Residual pressure, as opposed to static pressure. That is why I asked for static pressure, but now I'm wondering.

EDIT: With 48 psi pressure, you should be getting well over 10 gpm even through a long run of 1/2" pipe.

 

[daveg01]

The flow at the meter is actually 3.5 GPM and it drops to a little less than 2GPM at the upstairs tub.

I really want to avoid digging up the yard to deal with the outside waterline since that will get very expensive. I realize 3.5 GPM is pretty poor. That said, it would make a big differnce (comfort wise) if I could get the 3.5 GPM to my oulets.

 

[Diehard]

The flow at the meter is actually 3.5 GPM and it drops to a little less than 2GPM at the upstairs tub.

I really want to avoid digging up the yard to deal with the outside waterline since that will get very expensive. I realize 3.5 GPM is pretty poor. That said, it would make a big differnce (comfort wise) if I could get the 3.5 GPM to my oulets.

Okay ...I understand your concern. In the absence of a response to my last question regarding location of gauge while it was flowing I can only conclude that you did not do a residual pressure test. That I suppose should have been obvious when you came back with a static pressure of 48 psi when I had thought the 3.5 gpm was at a pressure of 48 psi.
I apologize if I confused you or if it is too technical for you but a true test of water supply capabilities is both a Static pressure test(non flowing pressure test) AND a Residual pressure test(pressure while flowing.

In any case, does it cost you to question the water supplier about the problem? It is possible that it could be in their meter.
If you want an idea what you would get for water flow at the upper levels of your house through non restricted (in house) piping, run a 3/4" hose from your 3.5 gpm spigot, as a test.

I don't think I can help you any longer on this problem as I do believe it is a restriction in your main line.
Good luck.

 

[daveg01]

The 48psi at the meter was a static pressure measurement. I took it at the new garden hose connecting that we installed right after the meter. I have not tested pressure at the meter with water flowing.

The closest thing I have done to the residual test was in the third floor bathroom.
I tested the sink pressure with the tub on/off.

Tub Off

Sink flows 1 GPM at 40 PSI​

Tub On

Sink Flows .5 GPM at 5 PSI
Note: "Total water delivered" to third floor (tub+sink) is roughly the same (2 GPM) with the tub on/off​

Now that I have an additional garden hose connection right at the meter I can do a better residual test. I can hook up my pressure gauge inside right next to the meter and turn the outside spigot on. Hopefully this will be close enough to a residual pressure test.

My neighbors also complain about very poor water pressure so I suspect that the 3.5 GPM might be all the city is able to deliver. Also note, the line from the city main is copper.

My next steps are:
- Test residual pressure at the meter using inside garden hose connection and turning off exterior spigot
- Test neighbors water pressure at an exterior spigot
- Test water flow to 3rd floor using garden hose connect to the interior connection.
- Call the city and ask what the expected capacity is for my location

Thanks for all the help you provided, it was very helpful.

Also, can you or anyone else comment on whether or not a booster pump would help with this problem. I don't understand how they work, but my instincts tell me they do not increase the pressure on the supply side and hence can't increase the delivery to my system.

 

[Diehard]

You should contact a reputable booster pump supplier/application person for their input. But as I see it, if there's a restriction, the supply pressure will drop of quite quickly when a pump tries to draw additional water.(That's part of the reason for a residual pressure test.) A centrifugal pump requires a certain amount of suction pressure to operate without cavitation. This is called the "pumps NPSH requirement". Google this and you will learn a bit more about what that means.

Without a good analysis of the water service capabilities, flow vs pressure, it's difficult to say. It may work okay up to a point. A good pump person can match it to a particular pump and probably improve your conditions. But I would expect that they would do their own residual pressure test. There are different types of pumps with different characteristics and different NPSH Req'ts.

There are a lot of people that may think they have the answer, but really don't know for sure, so any advice you get triple check it before you commit yourself.

It will be interesting to see what you get for information from the water purveyor. They may wing it too. Don't be afraid to question anything they say if it doesn't sound right.
If you're getting 48 psi static pressure you have to expect double digit flows.

 

[Valveman]

A booster pump will give you all the pressure you want, if you can give it enough water to work with. Like Diehard says when you start sucking on the mainline, the pump may not get enough water to work properly. When the supply gives enough water adding a booster will help. When the supply cannot supply enough water, the booster needs to draw from a cistern storage tank instead. The cistern can be filled with city pressure using a float valve like for a toilet. Then the booster will have 300-1000 gallons to work with as needed. Stay away from the booster pumps like Franklin that use a variable speed or VFD for control, and also stay away from flow control units like the Masscontrol or Duramac, Burcam things. A regular jet pump like a Goulds J5SH will give you all the pressure you want, and controlling that pump with a PK1A constant pressure kit will make it last a long time and deliver strong constant pressure in the house. See this drawing of a cistern system using a well pump to fill the cistern. Yours would have a float valve from the city supply filling the cistern.

 

[frodo]

I was hoping someone could help me diagnose a water pressure/flow issue I have in my house. We have sub-optimal water flow in the showers and it drops considerably when we turn on other fixtures. The house is 2 stories with a basement. It is a mix of galvanized and copper and the main coming in from the city is copper.

I ran a few tests.
1. 3rd floor bathtub = 8 quarts/minute
2. 3rd floor sink = 4 quarts/minute
3. 3rd floor sink = 40lbs
4. 3rd floor sink = 5lbs when tub valve is open
5. 3rd floor sink = 2 quarts/minute when tub valve is open
6. 3rd floor tub = 5 quarts/minute when faucet is on
7. 3rd floor tub and sink are bone dry when basement laundry sink is wide open
8. Basement laundry sink = 8 quarts/minute
9. Kitchen sink (1st floor, above laundry sink) = 4 quarts/minute

Is this enough information to point us in the right direction?

Any help would be appreciated.

Thanks

Hello, I skipped all the other responses because the problem is the galvanized piping
it needs to be replaced, BUT, you have another problem, the piping is mixed copper/ galvinised
so instead of just re piping you need to remove the galvanized pipe, and disconnect/ remove the valves under sinks, toilets, and washer, blow the lines out with compressed air, because some of the galvanized garbage has moved into those lines.
you need a re pipe . which is my specialty, but i do not live near you

if you are seeing
Meter: 48PSI and 3.5GMP
3rd floor bath: 40PSI and 1.25 GMP
Basement laundry sink: 45 PSI and 2 GMP

it is not a psi issue, it is a pipe size [volume] issue
due to the old pipes being full of calcium deposits

 

[Diehard]

Hello, I skipped all the other responses because the problem is the galvanized piping
it needs to be replaced, BUT, you have another problem, the piping is mixed copper/ galvinised
so instead of just re piping you need to remove the galvanized pipe, and disconnect/ remove the valves under sinks, toilets, and washer, blow the lines out with compressed air, because some of the galvanized garbage has moved into those lines.
you need a re pipe . which is my specialty, but i do not live near you

if you are seeing
Meter: 48PSI and 3.5GMP
3rd floor bath: 40PSI and 1.25 GMP
Basement laundry sink: 45 PSI and 2 GMP

it is not a psi issue, it is a pipe size [volume] issue
due to the old pipes being full of calcium deposits

View attachment 17996 View attachment 17997

Forget the rest of the house piping. He's only getting 3.5 gpm at the nearest spigot to the meter. So unless this few feet of pipe between the meter and the spigot is partially blocked he's not getting adequate flow through the meter. Those pressures you show above are all static pressure. If residual pressures were recorded, you'd see a BIG drop in pressure at the meter.
RESIDUAL PRESSURE is the key.