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Hey guys and gals,

Quick question.. PVC COEX, when cut, has a dark grey inner core compared to its white shell.. does anyone here know if this could be potentially toxic?



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I don't know. 

Most of us try to avoid using the "foam core" PVC pipes in situations where the "foam" would be in water contact since I doubt that part of the pipe has been tested for potable water or food safety.  I try to stick with the solid pipes and would probably make a point of avoiding the foam core pipes for use in things like "gravel guards and siphon bells where there would be an increased core contact with water.  That is just what I've done because I haven't been able to find info about the material's safety.

Adam all pvc is food grade or the correct term potable water safe. It is cut and glued and the cut ends are in constant contact with water surfaces when full. You are safe with all pvc and cpvc.

Hay David, are you sure on that?  There are pvc pipes meant for drain/waste and vent and sewer pipes that are not meant for potable water.  There are also pvc pipes that are meant for electrical conduit.

The PVC being asked about is only a pvc shell with a different substance between that is not PVC but some sort of foam and I've seen similar pipes that were labeled for DWV pipes

TC we have centex extrusion here which makes pvc pipe. They make all pvc for electric and pot water. The pipe is just a different color same resin. As far a abs and drain piping it is all safe because all waste water ends up in the enviorments. There are strict standards for all water pipe. Even drain tile is safe due to it is used to drain and collect water for waste and reclaim. This changed about 12 years ago, The pipe industry is very cautious about leaching due to every tradesmen uses every type of pipe in a different manner. ABS is meant for drains only because it is a lower quality resin due to low pressure requirements. It is still pot water safe. Since the plumbing industry has dropped clay pipe with asbestos and lead pipe 25 years ago our new generation of piping has had a great track record in regards to public health. Now that being said the chinese crap coming in is a crap shoot to say the least.
Good info to know.  I know that different types of PVC (like the flexible vinyl) can have different things in it that some people don't like and in the past lead was used as a PVC hardener in things like blinds but it is good to know the industry has gotten "safer" on piping at least.
thanks for all the info guys... my problem is the siphon strain pipe.. couldn't find potable water pipe in 4" .. so essentially with all the holes drilled in it and constantly submerged, yah i'm kinda freaked out about it.. .. but, i am gonna go out today and try to find something that's continuously the same material!
TC you are refering to the evil BPA used in "flexible" and "clear" pvc. Plastic of types 3 6 7 9 should be avoided if your concerned about BPA leaking into your system. Rigid PVC is safe and should not leach unless you expose it to crazy temperatures near melting point. Flexible pvc however does use BPA and can leach.

On another note, most environmentalist don't like PVC because of it's life cycle. If you are really really worried about chemicals look into HDPE piping ... it can be hard to find however, and fittings even harder.

Just for some perspective too, I read a lot of news every day and the more I read the more I think environmentalist rather have every human just kill themselves so as not to harm the planet. So when reading studies see who funded it, and if it has been verified by other studies as well as published in a respectable journal.

Yep you are right Burton.  Yes the worst part about the rigid pvc pipe has more to do with it's manufacturing than with anything it might leach into water.


And there is food or potable water safe plastics and some of them do contain stuff like PBA but are still "safe" according to the FDA or who ever gets to figure that out.


Sigh just gotta choose you comfort and spending level.  Now I suppose one could get a sheet of HDPE plastic and roll it into a cylinder and cut slits or holes in it for a gravel guard.  Or there is food grade polypropylene  mesh that I've used for gravel guards.

Get to Know Your “GOOD & BAD” Recyclable Plastics by Number



HDPE pipe is a primary alternative to PVC (polyvinyl chloride) pipe for all piping applications and

is rapidly gaining market share for potable water, sewer, conduit and ducting, DWV (drain, waste

and vent,) agriculture, and ground drainage uses.



PVC creates dioxin, the most potent carcinogen known, as well as ethylene dichloride and vinyl chloride. These toxins can cause severe health problems including cancer, endocrine disruption, neurological damage,birth defects, and reproductive and immune system damage.




#2 - HDPE: high-density polyethylene is used in milk jugs, detergent and shampoo bottles, and, because it hasn't been found to leach, will replace polycarbonate in a new Nalgene bottle (more on that in a sec). It has also has not been found to leach, and is widely accepted and easily recycled.








No dioxin produced in manufacture

High abrasion and chemical resistance

Less susceptible to surge shocks

Seamless joint connections





PVC Pipe

Contains chlorine

Dioxin produced in manufacture

Moderate abrasion and chemical resistance

More susceptible to surge shocks

Joint seams can leak



#2 - HDPE: high-density polyethylene pipe: 

Back to the 'foam core' in 4" PVC pipe - what is the foam core made out of?

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