So I JUST had my plumber replace the service feed to my house with a soft copper 1" dia. line, which was originally 3/4" dia. GSP from the street to the house (~35' as the line lays). I wish I had taken a picture of the old line that was removed, because I've seen clogged arteries on the surgery channel that looked better than that... I mean, you couldn't even shine a light through a short piece it was plugged/rusted up so badly! Amazing we had any pressure (edit: FLOW) at all...

Anyway, the meter at the street is also 3/4" dia. on either side (located inside a box, built into the sidewalk), and is being fed by a 1" dia. line running in either direction under the sidewalk. The point on entry into my house is still 3/4" dia. GSP, and I know most (if not all) of the fixtures inside the house are all fed by 1/2" dia. copper lines from the slab, but I don't really know what happens to the 3/4" feed after it enters the wall (i.e. does it go down below the slab or is it cast into the slab? how much further does it go before it splits up into 1/2" dia. copper runs? etc.) Oh, and the water heater is on the opposite side of the house in the garage too (great design - not!), so it always takes a while to get hot water in any of the faucets/showers. This was one of the mains reasons we did this project to begin with.

So to complicate matters a bit further, I added a Home Master 2-stage whole house filter as part of the line replacement (right at the entry point to the house), which has 1" ports one either side and two REALLY big 20" tall canister style filters. Apparently it has less than ~1psi pressure drop across the system according to the manufacturer (which I tend to believe), but I plan to eventually install some gauges and confirm.

Now it's only be 24hrs since the upgrade, but I have not noticed any significant/noticeable improvement in water pressure (or flow) using normal faucets and shower. The hot water still takes about the same time, which is unfortunate, and a sink + tub scenario still leads to a pressure drop in both fixtures. However, one of the garden hoses (opposite side of the entry point) seemed to have more pressure when I tested it last night, but the pressure dropped off after about 10 seconds or so which I'm guessing is because the new 1" feed is so short and only provides an initial boost in flow/pressure (right?)

So my question is: Even as badly clogged/corroded as the old 3/4" GSP line was, shouldn't I have seen a more substantial improvement in pressure and/or flow by upgrading to a NEW, much larger 1" dia. line? Or do the 1/2" lines inside the hose restrict flow/pressure and keep everything about the same? And does anyone think that the 3/4" meter at the street may be causing a restriction at all? Would replacing it with a 1" in/out version help any?

Sorry for the long rant and multiple questions, but I'm trying to see if there is anything else that we can do to help get a bit more pressure (aside from replacing all the pipes in the house, of course).


2 Answers 2

  • "shouldn't I have seen a more substantial improvement in pressure and/or flow by upgrading to a NEW, much larger 1" dia. line?"

Not if the downstream galv. pipe at the entry point to your home is in the same condition as the pipe you replaced.

  • "does anyone think that the 3/4" meter at the street may be causing a restriction at all?"

Yes, but it is insignificant compared to the restricted galv. pipe downstream that you did not replace.

  • "Would replacing it with a 1" in/out version help any?"

Yes, after you change out the restricted downstream pipe.

  • "2-stage whole house filter... has less than ~1psi pressure drop across the system..."

All filters restrict flow. BTW, install a bypass line around your filter unit so it will be easy to perform maintenance or remove it from service (when you get tired of maintaining it).

  • "hot water still takes about the same time..."

When you increase flow by removing the restriction (old galv. entry pipe) the hot water will arrive sooner.

  • Ok, so replacing both the meter (at the street) might be a bit trick, since I'll likely have to call the city to shut down that line, since the meter is connected directly to the shut-off valve which I believe is 3/4" as well... Ugggh. Commented Apr 3, 2015 at 14:07
  • Joe, the water company wants to sell you more water... they will often install a 1" meter for you upon request for free. Commented Apr 3, 2015 at 14:17
  • Ooo, good point. Wonder if they would do the plumbing to reconnect to my new 1" feed too? Hopefully this wont involve the city and/or inspectors though :/ Commented Apr 3, 2015 at 14:20
  • And regarding the galv. pipe downstream: I unfort have no idea how far that goes into the house before it splits off and/or converts to copper. I have no crawl space so the lines are either under the house or cast into the slab, which would make them very difficult (read: expensive!) to replace. I tried tracking down plans at the city/county, but it's a 1967 built date and neither entity claims to have any records from then... Commented Apr 3, 2015 at 14:21

The time delay between the hot water tank and the places where you use it is entirely determined by the distance between the two, which you have not changed. Note that larger tubing would be counterproductive here, because the flow is almost entirely determined by the outlet device, and you want to minimize the amount of cold water you need to drain before you start getting hot water.

Similarly, the pressure drop issues when using more than one tap are also related to your inside plumbing. What this tells you is that the badly corroded service pipe was not your "bottleneck".

The only way to improve the hot water access time is to move the tank closer to the places that need it. In a large house, this may require multiple heaters, possibly including on-demand "tankless" type heaters.

The only way to improve the pressure drop issues is to redo the interior plumbing, either by using larger tubing, or making every tap a separate run from the main distribution point. With modern PEX tubing, the latter option is less trouble than you might think.

  • "entirely determined by the distance between the two..." "flow is almost entirely determined by the outlet device..." not true, a bathtub spout presents insignificant flow restriction. Increasing available pressure/flow by removing upstream restrictions will certainly improve hot water delivery time. Commented Apr 3, 2015 at 13:19
  • Thanks Dave. I have thought about adding a small tankless unit (or two) under each bath cabinet, which may be a cheaper/easier option to get quicker hot water than replacing the plumbing inside. However, I would still have the poor press./flow issues, so I will try to at least replace the meter and as much of the original 3/4" gsp line as I can... Probably have to cut a portion of the ext. block wall and excavate under the house a bit to see where it goes. HOPEFULLY there is a manifold or junction point nearby. I just had my attic blown so I'd hate to mess all that up by running PEX up there. Commented Apr 3, 2015 at 14:30
  • Blown in insulation isn't delicate, just inconvenient. You can shove (or shovel) it out of the way while working and shove it back in place when you're done.
    – Zhentar
    Commented Apr 3, 2015 at 16:20
  • Yes, but it's my understanding that you tend to loose some of the R-value when you move/disturb it, and considering my attic is really more of a crawl space than an upright/walking one, and running new lines to each part of the house would require a lot of moving around up there... I realize it may be the only way to get guaranteed improvements, but I'd like to see if upsizing the meter and replacing as much of the old 3/4" GSP inside the wall / under the slab as I can will help enough. Commented Apr 3, 2015 at 17:29

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