We recently moved into a new home and have been blessed with sloppy plumbing and high water pressure. The whole home is copper and since moving we have had 3 leaks in various joints. I'm no expert but I can clearly see poor soldering, overfilled joints, burnt flux, and poor clean with flux everywhere, etc...

Given the above I want to install a "smart" valve, I bought a Phyn Plus for the job. Originally, I had thought the line coming into the home was copper but after taking things apart I found what looks like PEX with an interesting PVC coupler to copper with newish looking crimped couplings. There is also no Pressure Reducing Valve so I will need to add one. At this point I'm wondering what scope of work I should ask the plumber for.

I think these are the problems: A) No PRV. I'd also like a pressure gauge to see what the pressure is on both sides of the valve. Worthwhile? B) Within the first few feet of pipe into the house I already have multiple couplers and nothing is strapped down. I'm thinking I could clean that up. C) Would it be worth going from the incoming PEX to my own new Uponor PEX run. That PVC coupler looks super sketch. This would be a good start towards repiping the house down the road.

Any thoughts would be great!

Main Water Valve

  • Slight terminology correction: "pressure gauge" not "meter" if interested in the pressure on each side of the new PRV you'll be installing.
    – Ecnerwal
    Dec 2, 2019 at 19:15
  • I edited the post. Any recommendations on a good quality pressure gauge to put inline?
    – umhelp
    Dec 2, 2019 at 20:57
  • @umhelp At SEVEN HUNDRED dollars, the Phyn doesn't even tell you the water pressure??
    – MonkeyZeus
    Dec 3, 2019 at 13:24
  • Phyn does keep track of water pressure, but that would be after the PRV. I want to see the pressure coming into the house as well. It doesn't really buy much other than fixing my curiosity. I also got Phyn for a lot less than that gotta love this sales season!
    – umhelp
    Dec 3, 2019 at 14:07
  • Oh okay, well it you really want the gauge before the PRV then you probably need more pipe length. However, if you set the PRV to 75 and the Phyn reports 75 then you know your incoming pressure is equal to or greater than 75. If Phyn reports less than 75 then that is what you are getting from the from the city.
    – MonkeyZeus
    Dec 3, 2019 at 14:33

2 Answers 2


That blue water service line could be PEX, but it also could be HDPE. If it's HDPE then it might be CTS (copper tube size) or IPS (iron pipe size). Based on the shade of blue I'm leaning toward HDPE, but it's hard to tell in a photo. Use a small mirror to inspect the full circumference of the pipe -- it may have something printed on it indicating the type. You also can measure its outside diameter and based on that narrow down the possibilities. In my (limited) experience, the blue coating on HDPE tubing is thin. If you scraped a little away and found black plastic beneath then it's HDPE. You could also test opacity with a flashlight: PEX is somewhat translucent but HDPE is very opaque.

Because the PVC adapter makes you uncomfortable you could replace it with brass. If the blue tube is PEX then this is easy an inexpensive: use a barbed fitting with a crimp or clamp ring, or use a push-on fitting ("Sharkbite" or other brand). These are readily available in any home improvement store. If it's HDPE, though, you'll need a different kind of adapter. These are going to be harder to find because they're normally sold through waterworks distributors. Expect to pay about US$30 for one of these. They're likely to sell over the counter to the public, but figuring out the name of your local waterworks distributor may be a challenge. If you got lucky at Home Depot you might find a plumbing associate who'd know a name. Somebody in your municipal water department may also be a good referral source.

In any case, I'd adapt the blue plastic tube to a brass male pipe thread and set a quarter-turn ball valve on top. The PRV would be down stream of the valve. Pressure gauges are a fine idea (I've done the same at my house), and if you want to incorporate these, then insert a tee between the valve and the PRV and another downstream of the PRV. Use tees with a threaded branch so you can screw in the right reducer bushing to work with your pressure gauge (probably 1/4").

  • The piping says Plastic Service Blue 3/4" CTS-OD. Thats all I can see on it.
    – umhelp
    Dec 2, 2019 at 21:33
  • CTS-OD is actually very good to know - that means it's the same size as copper "Copper Tube Size" so should be compatible with brass sharkbite connectors. Of course, you say the PVC part is a flo lock which means it has metal "biting" rings in it already and is like a precursor to the sharkbites we have now.
    – JPhi1618
    Dec 2, 2019 at 22:04
  • Well.. there ya go. It's HDPE, not PEX. Even though it's CTS outside you may need to consider inside diameter -- some Sharkbite fittings have a stiffener insert built in; if the insert doesn't fit the tube right then the fitting may not go on (insert too large for tube's ID) or it may be less reliable (insert too small; tube wall could deform and leak). If the tube is SDR9 (standard dimension ratio) then the ID might average 0.669", but if it is SDR11 then ID might average 0.705" (per JM Eagle spec sheet). PEX ID is 0.681".
    – Greg Hill
    Dec 2, 2019 at 23:39
  • Would there be a different manual compression fitting that would potentially work better than a shark bite? Not that they are bad but I got one that had a nick in the washer and it leaked a few years back. 100s of fitting in a box at the big box stores is asking for damage. Would a call to the county maybe help me track down the dimensions?
    – umhelp
    Dec 3, 2019 at 14:10

As far as I can tell that coupling is called a PVC Compression Coupling and according to the product page it should only be used to connect PVC and/or galvanized piping. In the Q&A section of the product page the manufacturer states:

This is designed for connecting piping and repairs of PVC and galvanized pipe. It is not directly compatible with Pex. You would need an adapter.

So lets pray that they used an adapter; not sure if the connection to copper requires an adapter though.

If you're willing to address that issue then you would need the city to shut off the water supply, disconnect the PVC coupling, and use a Sharkbite push-to-connect coupling rated for pex and copper. DO NOT try to solder on a brass female sweat adapter to the copper line because that copper cold compress fitting has a rubber gasket inside and heating the copper would deform it.

If you want to install a pressure reducing valve then I would recommend doing so on the residential side of that shut-off valve so that you won't need the city to turn off your water if you encounter issues. So that means you would have to tear out some more of that peg board.

Before installing the pressure reducing valve you should check how much pressure you are actually getting and make sure that everything before the pressure reducing valve such as the shut-off and couplings are rated for the pressure.

  • 1
    I couldn't find a great picture, but that is probably a "Flo Lock" coupling that is used with poly water service pipe: amazon.com/NDS-710-10RTL-Flo-Lock-Coupling-1-Inch/dp/B0013KSFP8 It has metal grip rings in it like a sharkbite fitting so they are much better than a plain ol PVC compression repair coupling and made for "copper sized tubing" like pex, polybutalyne and... copper.
    – JPhi1618
    Dec 2, 2019 at 20:38
  • @JPhi1618 I see, but it concerns me that the Home Depot product page for Flo Lock explicitly states "Non-Potable Water"
    – MonkeyZeus
    Dec 2, 2019 at 20:44
  • That's just some standardized table that has info some button pusher typed in or some system tried to parse from another source. The product description says "Lets you take advantage of cost-saving, time-saving polyethylene tubing for water service conditions", and I can tell you they are common adapters in the Dallas area where I have seen quite a few water service runs done in black poly pipe.
    – JPhi1618
    Dec 2, 2019 at 20:48
  • I was able to find a marking on the side 710-07. It looks like it is an NDS 710-07 Flo-Lock PVC Coupler. Is there a better product that I should be looking for or just leave it?
    – umhelp
    Dec 2, 2019 at 20:54
  • 1
    @umhelp I don't think so; you can probably just leave it. The 710-07 is rated for 200 PSI and safe for Pex. At this point I think you just need a pressure reducing valve on the residential side of the shut off valve and then the Phyn plus should be fine.
    – MonkeyZeus
    Dec 2, 2019 at 20:58

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