SDR-21 or Schedule 40 PVC

[nrc17gto]

Hi everyone,

Before too long we plan to work on digging the trench for the water line to our house build. It is going to be around 1700'. I have gotten a few mixed suggestions from pipe suppliers on what I should use. One is highly recommending the SDR-21 pipe that has gaskets built in. The other just suggests Schedule 40 with bell ends. I was originally thinking the schedule 40 but I have just learned of this SDR stuff.

What are your thoughts? Any experience with the SDR-21?

Thanks,
Nick

 

[SPIKER]

I would look at roll type poly tubing and forgo ANY joint type tubing. Chance at leaks are greatest at a joint and damage from shifting or weight from above is much greater for the joint and hard type materials such as the ones mentioned.'

Mark

 

[Qapla]

What size pipe are you using?

We have built mainlines with solvent PVC (schedule 40) that are much longer then the distance you mentioned and have not had any problems with the joints as long as they are properly glued. For anything 4" and under we have never needed anything other then solvent PVC.

Keep in mind, I am in Florida and we do not have a "freeze line" to worry about. But, properly buried at depth, PVC should work just fine.

 

[EddieWalker]

First off, SDR stands for Sewer Drain and is not to be used for anything under pressure. It's strictly a drain pipe.

Do not use poly. It stretches in the ground until it breaks, then you have to fix it, and once you fix it, it's just a matter of time until you have to fix it again.

Same thing with Schedule 40. It will break on long distances. The problem is caused because the ground moves with the freeze that cycle. Even if you completely enclose it in sand, like is required in some areas, but not everywhere. The ground moves all the time. In some soils, it's measured in inches over short distances!!!!!

Water lines with gaskets allow the pipe to slide in and out of each other over long runs and is the current best thing you can buy. You have to pay attention to what you are doing when you install it, but once it's installed properly, you will never have any problems with it.

C-900 or something similar is what you want to be looking for. Be sure to get the grease to put it together. On long runs, it's also a good idea to put a small amount of bleach crystals in each joint. Then when you pressurize the line, you need to bleed the water out for awhile to get the bleach and contaminates out of the line before drinking it. On bigger lines, you have to get a water test to be sure it's safe to drink. If you don't put the bleach in there, you don't have any idea what you will be getting out of it.

Good luck,
Eddie

 

[avillahdw]

As a hardware store owner with one if our primary lines being plumbing, I would much rather sell someone belled end sch 40 to be glued than gasketed pipe. The gasketed pipe, if not properly "anchored" periodically on long runs, will blow apart, particularly if you have any elbows. The only thing holding it together is its inability to move and when you pressure test it in a ditch, the odds are it's going to move. I ran an 1100' foot service with 1-1/2" glued sch 40 and have had zero leaks in the 8 years of service. As for roll poly pipe, I would bet you won't find a continuous roll 1700'+ in length, meaning somewhere you are going to have couplings. Even with the "tuff tube" service pipe, if you have even moderately rocky soil, over time you will have leaks from expansion/contraction of the soil even below frost line.

 

[varmint]

Thanks, Eddie. I didn't know this, but it makes perfect sense. I woulda used poly, but your point about stretch (and shrinkage) is true!

 

[Grn mtn boy]

SDR does not mean sewer and drain. It stands for Standard Dimension Ratio. I've put a lot of SDR in the ground. My current house has about 600 ft of 1-1/2 inch with 100psi + on it with no problems. I live in northern Vermont where it gets plenty cold. Pipe should be buried below frost line for obvious reasons. It's not going to blow apart if installed correctly. Place thrust blocks behind any bends to distribute the force created into the compacted soil behind it.
Gasketed pipe with go together much faster than glue joints. Another thing to consider is the solvents needed for glue joints.... You're going to be drinking that water. Gaskets pipe uses a soap lubricant that's potable.

 

[EddieWalker]

SDR does not mean sewer and drain. It stands for Standard Dimension Ratio.

Thanks. I looked this up and saw that I was wrong. The utility companies that I've worked with all call it sewer drain pipe, so I assumed that's what SDR was short for. I've installed some of it for drain lines, but since they are usually pretty short, I usually use Schedule 40

For water lines, I've used both Schedule 40 and C 900. The big deciding factor is distance. For long runs, the gaskets allow movement in the ground. Going deep doesn't eliminate all the movement, but it helps. Black Poly will still fail. I realize that some people will go their whole life without failure, but I also know that in the grand scheme of things, black poly is more prone to failure then just about anything else.

Eddie

 

[nrc17gto]

Sorry I should have mentioned I am going to be using 2". Water company wants it 24" deep here in Tn. The sdr that was recommended is a gasketed pipe for up to 200 psi. Here is a lowes example. http://www.lowes.com/pd_23993-1814-...22012+4294931368_4294937087?productId=3133107

From what I have read so far my main concern of the sdr-21 is it is not as thick as schedule 40.

Thanks for the input.
Nick

 

[TheGoose]

I've seen PVC break, but never at the bell ends. I would go with sch 40 pvc (which has a pressure rating of about 400 psig depending on size). Use the RIGHT type of glue and be sure to use primer.

Eddie, I have also dug up and repaired a lot of black poly pipe through the years but I learned that in some places they can get much better quality poly than we can get here in Tx. Most of the stuff buried here is rated for 80 psig but up north they can get 160 or 200 psi rated poly which is much tougher and is recommended by a lot of folks. No joints except at the ends.

 

[EddieWalker]

PVC Pipe

I did a little searching to educate myself and see how off base I was. This is a good link that explains it so I could understand what is what.

As for the black poly, I know there are several levels of pressure rating for it and that the higher the rating, the better it is, but that's not the problem. What happens is that the black poly doesn't handle movement very well and if there is any movement in the ground, it's just a matter of time until it fails. PEX is similar in appearances and cost, but designed and able to flex, expand and even freeze over and over again without failure. It's hasn't been around long enough to know this for sure or if it will last for decades in expansive soil, but from everything I've heard so far, it's pretty good stuff. If I was ever to think Black Poly was a good choice for something, I would definitely use PEX instead.

I have c900 to my house.

Eddie

 

[orezok]

SDR comes in 2 types and several different pressure levels. The SDR Eddie is referring to is probably SDR35 which is a non pressure sewer pipe.

SDR pressure pipe comes in ratings from 100PSI to 250PSI working pressure. The stuff carried at box stores is probably the low pressure stuff.

Prior to retiring I used to build schools. A high school may have 10 miles of irrigation pipe installed, most of which is pressurized by booster pumps running up to 100PSI.

Lines less than 2 1/2" were always schedule 80 PVC. Lines 3" and above were C900 with mechanical joint fittings. We used mechanical joints because as others have mentioned, the ground constantly moves.

Our long term failure rate was almost zero. I know that this is an expensive installation, but it is designed to last 50 years.

 

[speedbump]

I agree that Poly would be the best. I don't know what length rolls you can get in 2" as I haven't used Poly in over 30 years. I understand it comes in 200 psi, same as the SDR 21 that I use all the time. I have been using thin wall PVC for 30 years, only used primer once and have great luck with it. But in Florida, most of it is above ground. Poly might get squashed by a rock or other object if the trench isn't carefully backfilled, but it won't break. If you are going to use PVC, you will find that SCH 40 breaks quicker than SDR 21 will.

 

[SPIKER]

Up here we use at min the 160 PSI poly (which is much better than the old 1970's stuff which expanded in diameter a lot with pressure & could pull out of the ends.) The new stuff is very similar to PEX (cross linked polyethylene) and has very little shrinkage due to expansion. It is also much more flexible in trench if you have a poor or rocky soil to move it around underground rocks etc.

On the slip joint pipes these under movement in that run could stack up and end up having one of the joints pushed out under some conditions and at that you could have leaks every/any 10 or 20 feet section over your 1700 feet. Long term if you are connecting to chlorinated water not sure of the seal life under those conditions. These lines are somewhat new (I have not used them) many cities are in large diameter versions so much be somewhat good. That said the smaller diameter versions may end up with the absolute needs to make the trench flat and even spaced and surround the pipe with correct amount of correct sand. It would need a great deal of additional surface & trench prep and costs in materials & handling. Not sure how pressure testing them would work as under pressure they may want to PUSH (expand apart) and so would need fill over them and no way to be sure they were leak free?

Just as an FYI what I have done at my farm, using the 4" corrugated (solid not slotted/punched) field drain tile. I laid 160PSI black poly (cross-linked polyethylene potable water pipe) pulled it thru inside the tile. if/when I ever have to change it I'm hoping that I will only need to dig up the ends and slide out the pipe and put in new. However in past installs & current installs the line is ~4-feet deep around here for frost & I have never replaced a line due to it failing even in the 70's old black poly stuff. I have replaced frost free hydrants that had the poly at the bottom, due to the fittings breaking or hydrant getting run over/broken off from age/use. On both of those cases the poly was trimmed back a few inches and the NEW hydrants installed with a large Galvanized (upside down T for added support) and back up and running. The two I replaced was due to lack of proper support on the hydrant when originally installed (not sure when on both cases) & the previous person used plastic elbow fittings on/at the bottom. The wiggling of the hydrant using it opening/closing eventually broke the fitting the poly was OK.

No matter what you run be sure to install tracer wires and plastic tape a foot or so above the lines so you (most likely long down the road new owners) can locate the lines. also be sure to NOT have too many trees close to them. I would be afraid of issues with tree roots trying to get to damp areas on the gasket stye pipes should they be too close. Note roots are very powerful and have cause lots of costs fixing the damage they cause.

Quick google search found what looks like an interesting concept paper for underground piping & couple other places. FYI for chlorinated water you should look for pipe meets or exceeds "ASTM F2023" most PEX-A/B type PEX/XDLP if you go that direction.

http://plasticpipe.org/pdf/chapter07.pdf
Cross-linked polyethylene - Wikipedia, the free encyclopedia
Municipal Piping

Mark

 

[Qapla]

The tracer wire is a great idea. It does not have to be a large diameter wire but it does need to have a direct burial insulation on it. Checking with an irrigation supplier may be the easiest and cheapest way to find a suitable wire to use.

Keep in mind, I am in Florida and we do not have the freeze worries. That said, we installed irrigation along a roadway a while back. It was 3" mainline that went about 5 miles (that's about 26400 feet) and we used :thin wall" PVC. That has been about 8 years ago and no leaks yet. At home I have 1000 feet of 1 1/2" PVC that has been in the ground for 40_ years ... no leaks yet.