Replacing old galvanized water supply line from meter to entry at house

[k9mlxj]

Hi there,


Was looking into some irrigation issues earlier this week. Some folks suggested I still have old galvanized water supply line underground going from the water meter by the side strip area outside the house to the entry in the backyard at my house. Changing that old pipe out would remove the restrictive flow along that pipe due to rust in the galvanized pipe and restore water pressure to my house.

The total run from the water meter to the current entry pt in the backyard is 60 ft. Will be under the concrete in the last 7 feet and one 90 degree right turn for another 7 ft (underground), and there'd be a switch right after it comes up above ground next to the stucco wall just outside the garage.


Couple of questions:

- I wonder how far down does the water supply line go under the dirt? I see at the water meter perhaps it's a feet or two under. Does it go down deeper as the galvanized pipe goes thru' the sidewalk and into the backyard area of my house?

Or it stays around 2 feet deep under the ground level and heads straight into the house?


- what kind of pipe material would folks recommend to change out to? I talked to a plumber. He preferred heavy gauge 1" copper pipe as the supply line over Schedule 80 PVC. Any recommendation of one kind over the other? Is black polyethylene ABS? And, what'd be needed for either material (which kind of copper, which kind of PVC/CPVC, what kind of joint/solder, etc.)?


- I overheard there's some kind of machine where plumbers can use to pull the existing galvanized pipe out and insert new water supply line at same time w/o digging out from the dirt. Perhaps someone knowledgeable can explain a bit how this works?

The last 14 ft (see 2nd paragraph) before it gets into the entry of the house it'd be under concrete. Would this machine work, or the concrete would need to be cut to open up this area to replace the galvanized pipe?


I overheard there's a machine folks use to dig up trenches for irrigation piping. I wonder if that machine can also be used to dig up the dirt to expose the galvanized pipe. So no need for hand digging?



Here is the current local plumbing city info:

http://www.sanjoseca.gov/DocumentCenter/View/1770
http://www.sanjoseca.gov/DocumentCenter/View/10321


Thx much... .

[jadnashua]

FWIW, a small pipe (like a galvanized one full of rust) has nothing to do with static pressure. If you measured it, it would be the same as if it were a fire hose. But, it does affect the flow rate, which is what you notice. With the potential for earthquakes, I'd prefer something that is a bit more flexible than rigid copper. But, then, I'm not a plumber, nor from the Bay Area.

[Gary Swart]

There are companies that specialize in replacing supply lines without trenching. Just use the phone book or go to a plumbing shop (NOT a Big Box Store) and find out who they would recommend. They will use the size and type of pipe needed, place it at the proper depth, and take care of all of the details you mention. BTW, jadnashua makes an excellent point regarding pressure vs flow. Many people confuse the two terms, so don't feel dumb.

[k9mlxj]

Pls educate me on this one. So if the pressure w/o any water flowing (static pressure) is only 60 psi, is that too low already? And does that imply low water pressure when I use a shower? Water is from the city and not well water.


And then I heard of dynamic water pressure--is that the real water pressure when I'm using water?

Suppose I take a shower--the pressure drop is affected by the water line's rust condition--meaning, more water drop for same shower head if there's more rust in the galvanized pipe?


One reason I want to ask about how deep the galvanized pipe is when it goes into the backyard of the house, is that I am just wondering if this is something plausible for a DIYer.

I am getting close to $2k quote on this job, and my budget is just too tight for this unless I can find better job quotes.


If I can rent a machine that digs up a trench to reach to the galvanized pipe, I can perhaps remove that pipe and replace that myself (I've done some PVC piping/repair for irrigation in my lawn and replaced copper piping for shower valve before -- don't know if that's good enough to take the next step), or opening up a trench to the galvanized pipe would at least help make it easier for the plumber to replace it -- in return for a less expensive quote.


Have no idea, just wonder if I can rent a portable trencher machine to dig, or even use a pick --and if that can be deep enough to reach down to the galvanized pipe... . Or it's going to be more than a few feet down, so a trencher/hand digging is out of the question... .

[hj]

The line has to be below ANY frost line in your area, which means it can be 12" deep or it could be 72" deep, depending on how cold it gets in the winter time. IF you had an earthquake, copper pipe/tubing would NOT be affected, but PVC would probably fall apart. ANYTHING under 100', I ALWAYS use copper, but it does not have to be the "heavy gauge" copper tubing. There are many ways to install the new pipe, and you would have to consult with your plumber to decide which is the easiest, and/or cheapest. Tenchers will dig the trench for the pipe, but they will also destroy any wires or pipes they come in contact with.

[Layne]

I've only been to San Jose in the summer, but it never get's much below freezing does it? I'd be surprised if the pipe is much more than 1ft deep. I wouldn't personally want to use the trenching machine. If you hit the steel pipe with it you could damage the machine, so you won't be able to follow along the pipe and will probably miss it entirely in places. Plus most of them only dig about 4" wide, which is then not easy to finish with shovels. Just find 3 or 4 young people to do the hard part for you.

I've been trying to make the same desicion on what to replace a supply line with. My galvanized pipe has already been replaced with some PVC that needs to be replaced now as well. It seems that the pex is heavily favored. People even claim it will last longer than copper. There's a lot of corrosion issues to consider with copper and apparently you need to backfill the trench correctly to help prevent it. Also some codes require silver soldering of any copper connection that is underground. I'm not a professional by any means, just passing along the high points of my research on the same subject.

[k9mlxj]

It's northern California here. Snow in the mountains, but no snow down at the ground level. Occasional frost can occur in the morning on the car's windshield in the winter, but that's about it. Lowest temp at night is around 38F-39F in the winter. 34-36F at night in the winter can happen but not often. We consider that cold. ;-)


** If the depth is only around 1 - 2 ft, I can dig it down with a pick -- just take my time over a week or two in my spare time, or find some high school kids to do it.

The backyard is pretty bare now since the hot summer. I was about to redo the backyard due to too much weed, so no worry for lawn damage/any shrubs in the way. The only thing is the last 14 feet where it's very old concrete. Don't know if I'd need to cut it or I can try to just remove the concrete piece (see above pic).


** Does the main water pipe tend to run along the edge of the building structure, or out in the middle of the backyard and closes in for the last couple of feet (see pic)?





** BTW, how do I confirm there would be a potential corrosion issue? What's the pH (base or acidic) of the dirt to confirm there could be a potential of this corrosion problem to the pipe? The pipe is going to run under a lawn area for sure unless it turns to be close to the garage early on as it enters the backyard (see pic).


I've just done a water test. Static pressure is 60 psi at the house entry, but turning on each faucet would cause a drop of 10 psi. So, turning on the tub, kitchen faucet, and the hose bib in the front yard take the pressure at the house entry down to 30 psi (!)


I guess that's good enough indication it's a water flow issue at the main water pipe?


** This house is a 55 yrs old house, so I'd also need to consider if the main water pipe is being used as the ground (cannot replace with PVC if so?)

I do see copper pipes inside the house are also used as ground although there might already be a ground rod somewhere -- but I don't see any except one small rod used only by the cable company (see pics of electrical box and ground rod).




Seems like the pipe thru' the electrical meter is used as ground. Don't know if anyone knows enough to explain that... .

[jadnashua]

The drop in dynamic (while actually using water) pressure is caused by inadequate flow rates. Flow rates are affected by the size of the pipe, how many bends (elbows, or other restrictions), distance traveled, and elevation changes. There are tables that help to calculate the pressure drop over distance with various pipe diameters. And, you'd have (slightly) less pressure on the second floor bathroom verses the first, but the primary thing is supply line size and condition. 60# is a decent pressure. Anything over 80# should be regulated to 80# or less. Some people with a well live with the range of 20/40, so 60# is fine, if you can improve your flowrates.

[Layne]

** BTW, how do I confirm there would be a potential corrosion issue? What's the pH (base or acidic) of the dirt to confirm there could be a potential of this corrosion problem to the pipe?

As I recall the most important thing was to get the same material above and below the pipe (I believe they used gravel). Setting the pipe directly onto undisturbed dirt and then refilling with topsoil mixed in was the cause of the problem I read about. Definitely do your own research on it, I'm just recalling an article I read.

[k9mlxj]

Thx Layne for the information on corrosion -- v. helpful.


On the pressure drop issue due to flow rate problem, I tried turning on a hose bib in the front, and then another bib in the backyard individually. The pressure drop on just the front yard's hose bib was 30 dpi, and the drop on the hose bib in the backyard was even worse: 40 psi. It dropped from 62psi to like 22 psi. Hard to believe.


I called a plumber, and when he heard these data points, he suggested there's a problem with the main line--unless there is also a problem on the main before the meter--in which case my neighbors should all have similar problems.

I called the Water company and they're going to come do some tests next week. But I bet they'd tell me it's the old galvanized pipe.


I'd go off and check my neighbor's pressure if they have same problem. If they have new main pipes after their own meter and they don't have a problem like mine, then I know it's the pipe after the meter for me.


I think the main line coming to the house entry is 3/4" galvanized pipe. By the meter, I can even strip off the surface off that pipe--exposing some rusted part.

[Tom Sawyer]

90% of all new water service pipes in this area are PE and we have to go 48" deep

[hj]

quote; Also some codes require silver soldering of any copper connection that is underground.

ONLY underground' AND under a concrete slab, AND inside the structure. Has nothing to do with a water line from the meter to the building. And, if copper is used, it WILL be a single piece from the meter and UP OUT of the concrete, WITHOUT any intermediate joints, so it would be irrelevent anyway. You should be able to "push" the new pipe under the concrete slab, but WILL need to make a big enough hole to "bend it" up out of the ground. We, AND I, always use the native soil to refill the trench around the copper.

[bluebinky]

In Santa Clara, the soil is clay -- fairly hard digging. In my opinion, even if you dig by hand, it's a good idea to call the utility locating service just to be absolutely sure you know where everything is. Also, check who is supposed to turn off the meter. If you are not supposed to touch it (Santa Clara) and you break it...

I replaced my service pipe a while back. Everything here on these old houses seems to be buried at 12 inches. The city inspector wanted 12 inches of cover over the new service pipe. He was happy with the 1 inch type L copper, and didn't say anything about the joints (used sticks rather than a roll). When I mentioned rolled copper, he looked at me like I was from outer space. When I asked him about my using sand around the pipe, he said it was a good thing.

As far as the grounding -- if you go with PVC, you'll need a new ground rod. Actually, they asked me to put in one even though I was going with copper.

Assuming you are getting a permit, the approach that worked for me was going into the city office and asking to talk to an inspector so he could explain exactly what he wanted to see when I called him out. He rattled off a bunch of stuff in less than a minute and walked off. I did everything he said, and he was amazed that a mere homeowner "did it right". Kind of silly...

Recently, a neighbor called a contractor out to replace his leaking line and negotiated them way down by offering to do all the digging and filling himself.

[jastori]

On the pressure drop issue due to flow rate problem, I tried turning on a hose bib in the front, and then another bib in the backyard individually. The pressure drop on just the front yard's hose bib was 30 dpi, and the drop on the hose bib in the backyard was even worse: 40 psi. It dropped from 62psi to like 22 psi. Hard to believe.

Those measurements do not really mean much. Static pressure is measured when there is no flow. 60 psi is fine for static pressure. What you care about is whether your piping can provide adequate flow (gallons per minute) to all of the fixtures that you want to use simultaneously. If you want to simultaneously take a shower, water the lawn, and run the dishwasher, and you can't (insufficient flow), then you need to improve your supply piping.

[k9mlxj]

Thx so much for all the info--really very very helpful!


I called the Water Company telling them about the low water pressure problem when turning on faucets.

The technician came out and did an actual test:

- removed the water meter to my house
- he had a short 2' S pipe section set up so to reroute the Main line (from the street) where it originally meets the meter upward
- reconnected the rerouted pipe section to the water meter
- turned on water from main full blast thru' the meter, and timed the water amount that came out in 1 min


Water meter hooked up to house service pipe : 1.4 circle turn on water meter
Rerouted test : 5.4 circles turn on water meter

He said the water flow thru' the current service main (galvanized) line to the house was about 0.93 gallon/min from the test.

W/o going thru' the galvanized pipe, the water volume would be about almost 4 times more.


Looks like this confirms it's the galvanized pipe that's restricting the water flow (volume) problem.


He said that the depth of the water pipe should be around 18 inches down for this city.