city water pressure

[James2011]

I have a mat and the water pressure is normally 40psi, my question is is this city water supply pressure suppose to sustain 40psi continulously?
or it could be fructulated depending on water usage?
IOW, water supply city line's pressure is 40psi, then this 40psi should be same all the time? or it can be lower pressure when people use water?

[Adamski]

laundror,

Again, a first name would be nice since our site is so user-friendly.

To answer your question - municipal water pressure generally stays pretty constant because cities use a series of very large (1,000,000 gals or more) tanks to pressurize the system. These tanks are strategically located throughout the city to provide consistant pressure from various points into the entire water grid.

That said, there are a couple of situations that could temporarily reduce water pressure within the distribution pipes. They are:

A. A large fire requiring multiple fire units consuming large amounts of water.
B. A broken water distribution main.
C. A city well or pump that's down for maintenance if the system's demand is pretty close to maximum production capacity.

[James2011]

laundror,

Again, a first name would be nice since our site is so user-friendly.

To answer your question - municipal water pressure generally stays pretty constant because cities use a series of very large (1,000,000 gals or more) tanks to pressurize the system. These tanks are strategically located throughout the city to provide consistant pressure from various points into the entire water grid.

That said, there are a couple of situations that could temporarily reduce water pressure within the distribution pipes. They are:

A. A large fire requiring multiple fire units consuming large amounts of water.
B. A broken water distribution main.
C. A city well or pump that's down for maintenance if the system's demand is pretty close to maximum production capacity.

Thanks Larry,
city pressure measured in fire-hydrant outside street is 52psi, but entrance point in the building, the pressure is 40psi, there is 2inch underground copper pipe runs between outside city main and 2inch meter in the building.
12 pound pressure loss(drop) is normal? undergound pipe maybe damaged and could causes this problem? pressurre fructuates too much range from 5psi to 40psi inside building, is this abnormal, right? how can I check and verify the undergound pipe? maybe flow-test?

--Anderson

[Adamski]

Anderson,

With 52 lbs pressure at the fire hydrant out front, you should have 52 lbs pressure inside your building as well. A 2" copper service line should be plenty large enough if it supplies nothing but your laundromat. Things to check out include:
A. A leak in your 2" copper service line. It seems likely that any leaking water would show up at the surface of the ground though, since water is lighter than dirt.
B. Extensive internal corrosion where your 2" copper line attaches to the steel main.
C. A crushed service line. This seems unlikely to me unless you've had some really large equipment running over the area of the copper line.
D. A defective pressure guage that's reading too low inside your building.

[pressandclean]

The fire line and the domestic water are separate pipes from the main.

[Howard]

There is a difference between static pressure with no flow and dynamic pressure when water is flowing - the pressure you measure will be less when water is flowing depending where in the line you measure it and how much water is flowing and what restrictions there are.

[James2011]

Anderson,

With 52 lbs pressure at the fire hydrant out front, you should have 52 lbs pressure inside your building as well. A 2" copper service line should be plenty large enough if it supplies nothing but your laundromat. Things to check out include:
A. A leak in your 2" copper service line. It seems likely that any leaking water would show up at the surface of the ground though, since water is lighter than dirt.
B. Extensive internal corrosion where your 2" copper line attaches to the steel main.
C. A crushed service line. This seems unlikely to me unless you've had some really large equipment running over the area of the copper line.
D. A defective pressure guage that's reading too low inside your building.

thanks again Larry,
possibly A/B/C, not D because I bought two brand new water gauges.
A; there is water on the ground above service line, but I think its coming from other place, but I will double check it
B; strong possibility...we will see whether the flow test can reveal it or not tomorrow...
C; maybe possible, because they did asphalt repaving last year and they used heavy roller...

As you said, 12 pound loss means something wrong in serice line, who is responsible to replace this line? me or property owner? I looked at my lease document, desn't mention about this case...

--Anderson

[James2011]

There is a difference between static pressure with no flow and dynamic pressure when water is flowing - the pressure you measure will be less when water is flowing depending where in the line you measure it and how much water is flowing and what restrictions there are.

I attachd water pressure gauge at the end of 3/4" pipe ( 7inch long) which connects in the middle of 2inch pipe around meter, so no one use washers, reading is 40psi, when 3~5 washers run, the reading drops to 20psi, and depening on cycle, it moves back and forth from 10psi to 40psi...I don't know this measurement is static or dynamic, but this is the way I measure it, and this kind of fluctuation is normal or abnormal, which I have no idea.

--Anderson

[Howard]

That indicates to me that there is a restriction or blockage in your 2" main. You should be able to get a lot more water thought that without having much impact on the pressure.

[James2011]

a. there is man-hole outside which has old abandoned meter and water shut-off valves, today city folks came and he said the head-off old meter might cause this restriction problem, they will schedule to check it out in near future...

b. city inspector also stop by store with them and he asked who put 5 more machines without permit( he compared their record)? so, I answered previous owner probably did it. In this case, do I have responsible for 5 additional machines( getting permit, pay tap fee, etc)? or As it was done not by me and those machines were there when I purchased business, so I don't need pay money??

--Anderson

[Adamski]

a. there is man-hole outside which has old abandoned meter and water shut-off valves, today city folks came and he said the head-off old meter might cause this restriction problem, they will schedule to check it out in near future...

b. city inspector also stop by store with them and he asked who put 5 more machines without permit( he compared their record)? so, I answered previous owner probably did it. In this case, do I have responsible for 5 additional machines( getting permit, pay tap fee, etc)? or As it was done not by me and those machines were there when I purchased business, so I don't need pay money?

Anderson,

I wouldn't be surprised if that old, in-ground meter system is what's causing your low pressure problem. It would be nice to take that right out so that your service line connects directly to the main.

My guess is that you're responsible for paying the fees for the 5 additional washers since you're the person who is using the washers today. If you were to agree to take out 5 washers they might agree to wave the fees.

[STOUT]

Anderson,

My guess is that you're responsible for paying the fees for the 5 additional washers since you're the person who is using the washers today. If you were to agree to take out 5 washers they might agree to wave the fees.

Don"t you just love government!

[James2011]

STOUT, I tried to love GOV, but I was frustrated CITY water FOLKS!!, they are some kind of GOV, right? I don't like GOV!!

[James2011]

Anderson,

I wouldn't be surprised if that old, in-ground meter system is what's causing your low pressure problem. It would be nice to take that right out so that your service line connects directly to the main.

My guess is that you're responsible for paying the fees for the 5 additional washers since you're the person who is using the washers today. If you were to agree to take out 5 washers they might agree to wave the fees.

Larry,

In-ground old meter and above-ground-meter is different?
Both has some kind of mesh screen? or only in-ground one has it?

--Anderson

[Adamski]

Larry, In-ground old meter and above-ground-meter is different? Both has some kind of mesh screen? or only in-ground one has it?

Anderson,

I have no idea what your in-ground or above-ground meters might contain internally. The fact is you're having pressure issues and you need to clear your service line. A good start is removing that old meter completely. If that doesn't fix the problem, remove and clean any screen in your above-ground meter (if it has one).

[Adamski]

I have no idea what your in-ground or above-ground meters might contain internally. The fact is you're having pressure issues and you need to clear your service line. A good start is removing that old meter completely. If that doesn't fix the problem, remove and clean any screen in your above-ground meter (if it has one).

Anderson,

Have you resolved your water pressure issues? Did you remove that old in-ground meter? What was the cause of your pressure drop? Can you bring us up to date on what you've found so far?