Water pressure in master metered lines


#1

Our park has sections that have some older galvanized lines. We didn’t have any data on when they were installed, but I would assume they are from when the park was built ~60 years ago.

Someone from the water authority was out recently and took water pressure readings at two points. The readings are here:


(there was a water leak in a riser fixed part way through which is what caused the jump on this reading)

I spoke to the individual who conducted the water tests, and said the pressure drops too low and he thinks we should replaced all of our lines.

Does anyone with more experience on this subject have any thoughts or insights? It seems reasonable enough, but before I spent hundreds of thousands of dollars it would be nice to be more confident in my assessment.

Also, after doing some searching, there’s a company that produces a product that slowly clears out the inside of pipes:
http://www.blueearthlabs.com/scale-removal-and-deposition-control/
After researching some more it sounds like it could work, but would be a fairly slow moving solution. After installing a pump to administer the product it would only cost about $12 a day.

However, these lines are likely at the end of their useful life, so I would guess they won’t last long no matter what I do.


#2

Is the water provided by your own well or city water? Usual standard is 20 psi minimum.

Do you have a distribution system map. With out knowing pipe sizes and lengths it is pretty hard to do any calculatation to determine what is causing the low pressure. Can you give me some basic info: number of homes, Gallons of water used each day (or month), water meter size, mainline pipe size, length of mainline, mainline pipe material, pipe size feeding each house, …

I would not recommend the scale removal product. the mineral build up may be all that is holding your pipes together.

Dont just rush out and replace all the pipes. There may be more cost effective ways.

Phillip Merrill
Merrill Water Systems


#3

Thanks Phillip,
The water is provided by the city. I looked up the most recent water report and the water is on the harder side.

The park was a family run business before we took over that had kept no records on anything infrastructure related.

73 lots, 40 homes, approximately 5,800 gallons used a day through the master meter.

From the plumber who did an inspection during due diligence: feed line into the park is 2" copper, Feed line from 1st distribution shed to 2nd distribution shed is 2" poly tube. Riser feed lines to individual lots are 3/4" or 1/2" galvanized lines. the main lines the feed lines are coming off of are likely galvanized steel, but the size is unknown. I could have someone dig down and take that measurement

Here’s a really sloppy drawing of the park water lines by a leak detection company that traced the lines:

Using that drawing and google earth it looks like there is approximately 2700 feet of main line.


#4

Are the blue pen marks results of a pressure survey? If so something is way wrong because it is showing 20 psi closest to the city main.

Phillip


#5

No the blue pen marks are the amount of noise they were picking up on their leak detection equipment. However, they falsely identified several spots that were leaks that we actually fine (after we spent the money digging them up!) and missed the one main leak, so their accuracy is highly questionable.


#6

Do you know what the city main pressure is? I would do a pressure survey through out the park to see what is happening. My guess is mainlines are ok but the feeders that are 3/4 and 1/2 are the problem. 1/2" feeders are a joke if you take a shower the pressure will drop to nothing. Do a pressure survey of static pressure verses pressure while faucet is being run inside the house. I would check 5 or 10 homes especially since you are on the regulatory radar. My money is on the feeder pipes.

Phillip


#7

Thanks Phillip, great point! I hadn’t considered it could be just a problem with the feeder lines and not the main lines.

I’ll talk to a few plumbers, and see if they can take these measurements for a reasonable price, or if we might have the park buy the equipment.