Replacing main water line - Questions...

We're having our driveway replaced so I want to go ahead and replace our main water line that will end up being underneath the new driveway. It's galvanized and 40 years old so I'm hoping this will help our water pressure.

I have a straight 36 foot run coming from the meter to the house. I can see in the house it comes up through the garage floor, about 5 inches from the outside wall. Inside the garage, there is about 2 feet of 1" galvanized pipe coming through the floor before it changes to copper at a gate valve (part of this will be to replace with a ball valve).

My first question is what materials should I use? I went to Home Depot and Lowes last night and both told me to get 1" 160 psi poly (one guy said the 200 psi is overkill). A plumber I talked to said to use type K copper. Another said to use copper then to cover it with PVC to prevent it from breaking from any vibration on the driveway. Now all these options are making my head spin a bit and I'm not sure which way to go. I also heard that I cannot bring the poly into the garage and will need to change it to copper 1-2 feet outside - is this true? If not, how should I make the 90 bend to go from horizontal to vertical using the poly pipe (just bend it in a arc so I don't need to cut it and use fittings or get a 90 degree fitting with barbs on each end?)?

My next issue is how to bring this into the garage since the current plumbing goes through the slab. I'm sure I'll need to dig below the foundation on the front of the house but then can I just rent a rotohammer and put a hole through the floor to run the new pipe in? If so, how big should I make the hole (just a little bigger then the pipe?)? Is boring a hole a bad choice and should I instead break the floor up with a jackhammer?

I'm no expert in the area but have done a lot of digging and have also sweated a good number of copper connections in bathroom remodels so I'm hoping this is something I can tackle!

Any advice or input is greatly appreciated!!!

Thanks,
Brent

You may want to find out what code is for your area. Some places will not let you use poly pipe. But if you do, at least in my area, you must use the 200 psi copper tube size poly. If you do have to use copper, it must be k. I would sleeve the pipe comming through the floor with pvc. You can use a long sweep conduit 90 to make your bend.

I would use 1" type K copper with the PVC sleeve to protect it from rocks. You need to understand that your pressure will not be affected by the new pipe. Pressure is determined by you city main, not pipe size. The volume of water will certainly will be greater. It is likely your old galvanized 3/4" is about 1/2" because of corrosion, so only so much volume can be delivered at the pressure in the main. Enlarge the pipe and bingo, more water. Your city can tell you what your main line pressure is, and/or you can purchase a gauge at any hardware store for about $10. Screw it on to any threaded faucet in your home and, with all water in the house off, you can see what your pressure is. Ideally it should be between 40 and 60 PSI.

I would use 160 psi rated PE pipe, SS insert fittings with double opposed SS clamps underground, sch 80 insert fittings above ground with a single SS clamp.

I'd put it in 2.0" sch 40 as a conduit under the drive way and keep rocks away from under or over it.

It uses insert elbows, couplers, females, males, tees or a lazy bend works too. Don't over tighten the clamps. There is a torque wrench for them. Don't over heat the pipe to get the fittings into it. Hot water, sunlight or propane torch works well.

Millions of buildings with their own wells have PE run to the pressure tanks inside the building. PE has been used since the early 1960s. It is inert and adds nothing to the water run through it, unlike copper and, there is nothing in water that can harm it, unlike copper. It is the easiest to use and least expensive of all choices. IMO it is the best choice. Many water companies use it for service lines also. There is no legitimate reason not to use it.

If your present line is used for the building's electrical ground, you replace that with a #4 bare copper wire run to a proper ground rod or two.

Thanks so much for the input!

I really like the idea of running the line inside a 2" pipe for extra protection, but one site I saw said to snake the poly pipe in the trench so that some extra length is there to allow for any contracting or expanding due to temperature changes. The 2" pipe I was looking at using as a sleeve is rigid and wouldn't allow me to snake it around. Is the snaking a real issue?

I did take back my 160 psi poly and got 200 psi - the cost was hardly any more and the little extra wall thickness can't hurt (except when trying to push the barbed fittings in ).

I got the materials to bring the poly under the garage floor and have it go to a 90° elbow (barbed one end, threaded other end - it's gray plastic and was stocked next to the poly pipe but I'm not sure what material - anyone know what this is and if it is indeed OK to use in the main water line? It's what the guy at Lowe's said to use but he didn't seem to know what he was talking about). From the elbow I have a PEX fitting to go from the threaded end of the elbow to a bonding coupling for the PEX pipe that will come a couple feet into the garage before I have another PEX coupling to thread it into a ball valve that will tie it into my existing copper.

So why is it I can use the poly pipe to run up to the house underground but I then have to switch to PEX to bring it into the "visible area" in the garage? It seems very odd to me that it's good enough to carry the water to the house but can't be seen in the house.

Thanks again!!

Pressure vs. Volume

Gary Swart said:

You need to understand that your pressure will not be affected by the new pipe. Pressure is determined by you city main, not pipe size. The volume of water will certainly will be greater.

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But won't this greater water volume allow for better pressure in my household use? One of my biggest complaints now is that our water system doesn't have enough pressure to run a sprinkler to decently to water the lawn. I always thought of this being due to poor water pressure but is it really due to poor water availability (not enough volume being pushed into the house)?

Thanks - I do like to correctly understand the issue so I appreciate the comments.

I wouldn't stop until I got it up through the floor a foot of so. That's much better than threaded and crimped fittings underground. And if anyone said anything about it, I'd tell them not to buy my house or they can redo it anyway they want it done after closing.

As to the PE in the ditch, let it snake before and after the conduit, it is for expansion/contraction.

With new service line you will get much more water than with the old galvanized. Your pressure losses will be much less also, but it's not pressure, it's volume of water you want. I.E. 1 gpm at 100 psi is not good, but usually 10 gpm at 30-40 psi works for everyone.

You need to learn the difference between pressure and volume. Pipe and meter sizing will not change the pressure, that is determined by the pressure delivered by the city water main anyway. What will change is the volume of water that can be delivered at a given pressure. A 1/2" pipe has only 0.2 sq inches, a 3/4" pipe has 0.44 sq inches, and a 1" pipe has 0.785 sq inches of surface. Also to be considered is friction loss. It is greater in small pipe and will effect the volume that can get through the pipe.

Gary Slusser said:

I wouldn't stop until I got it up through the floor a foot of so. That's much better than threaded and crimped fittings underground.

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So are you saying to put an arc or long bend in the pipe to bring it up into the house and not have any fittings until it's in the garage? That certainly sounds good to me as I don't like the idea of all the joints I'd have underground, under the floor of my garage (poly pipe to barb in elbow, elbow threads to PEX fitting, PEX fitting to PEX).

What is the logic behind not having the poly pipe come into the house? Does it not have UV resistance (which wouldn't be a concern of mine in the corner of my garage away from any windows)? I'm assuming their is some kind of reasoning why people say not to do that and why I think it's against code confused to do so...

I have never heard of not being able to come into the house with the poly line. But, if it is indeed against code in your area, you could extend your 2" sleeve a couple of inches and put a junction box just above the floor. A plastic 6 x 6 x 4 electrical junction box should be just big enough to make your connections in, and it would give you an axcess to the connection.

Just a thought

Poly pipe failure?

Now I'm a bit confused... I was doing an internet search trying to find reasons why not to bring the poly in through the garage floor and found a couple of sites talking about how poly pipes will fail due to reacting with oxidants in tap water. If this is the case, why are so many people still using it as their main water line?

http://www.propex.com/C_f_env_polybu.htm
http://www.repipenews.com/

Should I step back and use copper or PEX? I'm doing the job tomorrow so really would like any feedback to this potential issue as soon as possible. Thanks again so much for all your help!!

mattbee24 - I love the idea of the junction box. I will probably go that route if I am able to bring this into the house. My only other issue is that my current piping goes up the inside wall and I don't think I could make a bend sharp enough under the wall footer to come back up and match to the current piping (after the bend in the pipe I imagine I'll be ~3 feet away from the wall. Any good ideas how to make this bend and keep it close to the wall?).

-Brent

The poly that they are refering to in those articles isn't the same as you will be using. Someone correct me if I'm wrong, but I believe they are talking about the piping used before pex pipe came along. I don't think you can even purchase that stuff anymore. They are talking about polybutylene, you will be using polyethylene. You shouldn't have anything to worry about.

mattbee24 said:

They are talking about polybutylene, you will be using polyethylene. You shouldn't have anything to worry about.

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Huge sigh of relief - thank you!!!

Gary Swart said:

You need to learn the difference between pressure and volume.

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Gary, who are you talking to? I can't see how you think I was disagreeing with you or that I don't know the difference between pressure and volume.

I was talking to the original poster, Gary, not you. I'm pretty sure you know the difference between pressure and volume. I think we had at least two topics under discussion at the same time and replies got mixed together.

Have ever tried drinking a milk shake through a tiny straw?

Works way better with the big straw.

https://terrylove.com/watersize.htm

Gary, I do the same thing, the memory lets me down.

Terry, that reminds me of last month when my wife got us some BBQ pork sandwiches from a Mom'n Pop place and they gave us like 3/16" straws. That feels weird but made the drink last longer.

Job done, thanks for great advice!

Hey all,

Just wanted to say thanks for all the great advice on this project. I did end up running the poly all the way from the meter to the inside of my garage for about 2 feet before it changes to copper. I do feel a lot better about not having any fittings underground except at the meter end. I don't ever want to have to dig that trench again...

I was shocked and disgusted by the site of the inside of the old galvanized pipes. I'll try to take a picture later on to post, but I couldn't even get a thin stick to push through a small section due to all the corrosion. I now have much better water volume coming through the house - enough to properly power a sprinkler to water the lawn!

Thanks again.

there will be a difference in pressure and volume. when there is not water running the pressure will be the same as the city main. this is static pressure. your pipe could be an eight inch and twenty miles long, but the static pressure will be the same if there is no flow. as soon as there is flow you create friction loss that will increase as the flow increase. the friction loss will be less for the same flow with a larger pipe. this means that the large the pipe the greater the pressure at the end of the pipe.

however, there is no pressure in your shower. absolutely zero. no shower anywhere has water pressure.