Piping - to PVC or not to PVC? That is the question...

[Sylvia Bernstein]

I use PVC, and I'm assuming that most of you do as well, but there are rumblings out there about it leaching carcinogenic nasties into the water.  My understanding is that this happens mainly when the pipe is heated, but that is exactly what we have in  the summer.  

 

Is anyone using an alternative in a bigger system? We've used some flexible vinyl tubing...but I sure prefer PVC.  Thoughts?

[Chi Ma]

You can use CPVC or PEX if it makes you feel better.

[TCLynx]

Well I know the worst part about PVC is the byproducts of manufacturing.

 

At this point in time I haven't found much other than kinda vague mention of PVC maybe not being good but I haven't found enough to make me switch to glass pipe or anything like that.  PVC Drinking water pipe is still better than flexible vinyl tubing in any case. 

 

I'm not willing to live in fear of the plumbing currently.

[Chris Smith]

I think that PVC is just as safe as the rest of the petroleum products that we use in our systems. I hear the same rumblings as well but about all petroleum products. The liners, tanks, pumps and in my case rafts are all oil based. I believe that these systems are safer, even with a minimal leaching,than most conventional farming techniques. PVC transmits water on most organic farms. I have not found any 3-eyed fish so I am not too worried yet.

Just about everything ,especially petroleum products, will release carcinogens when heated(enough). Even in summer your pipes are kept cool by the water inside. I doubt that your maximum operating temperature will cause any more "leaching" than your minimum.

[Sylvia Bernstein]

Thanks everyone for your thoughts on this so far.  I continued to do some research and concluded the same thing.  There seems to be 2 valid concerns about PVC pipe.  The first is what TC referred to with factory conditions.  The second is when plasticizers are used in PVC plastic to soften it to make children's toys (think rubber ducky).  I'm going to stop worrying about it!

[Rick Op]

I second TCLynx in PVC manufacture being a primary concern. With an additional footnote that this goes for its eventual disposal too - quite the nightmare!

In between its birth and demise, using it to transport my water, I am not sweating it. With another footnote here that high exposure to sunlight can eventually compromise it.

 

Which is why I am trying to use HDPE irrigation pipe where possible, where the fittings don't pose a solids buildup issue, and especially where a long run of it is exposed to sun a lot of the time. (It's even kind of fun to work with, pruners can cut it)

 

But PVC is frankly unavoidable in drain fittings, siphons, etc. and as for environmental impact, I apply the same philosophy as with concrete (for the same reasons) - re-use to minimize need for purchase and disposal.

 

My 2cents - worth price charged!

Rick

[Sylvia Bernstein]

Great perspective, Rick.  Thanks for that.  Other than a solids buildup issue (I'm assuming this is because of the way that PVC fittings fit vs HDPE), and the other unavoidable reasons you gave, are there any other reasons for using PVC over HDPE?  Like availability of size of tubing?  LIke availability and/or variety of fittings?  Cost?

[TCLynx]

Those reasons would play into my choices Sylvia.  I use some HDPE pipe for irrigation but the sizes/fittings available just don't suite for enough of what I would need.

Sylvia Bernstein said:

Great perspective, Rick.  Thanks for that.  Other than a solids buildup issue (I'm assuming this is because of the way that PVC fittings fit vs HDPE), and the other unavoidable reasons you gave, are there any other reasons for using PVC over HDPE?  Like availability of size of tubing?  LIke availability and/or variety of fittings?  Cost?

[Sylvia Bernstein]

I've actually never done a comparison of these two pipe systems so I honestly don't know the answers.  Everything we've done has been with PVC because it is so easy to work with, cheap, and easy to find a gazillion kinds of fittings.  My husband calls it an adult Erector Set.  If HDPE is recyclable, and has everything PVC has, though, then maybe we would switch for future systems.

[TCLynx]

Well CPVC is good for situations that has contact with hot water (like in your house where there is a hot water heater) I would not worry about water temperatures in aquaponics ever getting hot enough to compromise regular PVC.  But CPVC is more costly and generally smaller and you won't find the same array of fittings as you do for regular PVC in the big box stores.

PVC can become more brittle with long exposure to sun but then most plastics do.

PEX is not appropriate to sun exposure so it would need protection, same issues as with CPVC in that it doesn't normally come in very large sizes for drains or large systems needing big plumbing.  Also would need to avoid using the metal fittings when using it with AP.

 

The only HDPE pipe I've used is the black up to 1" coil of pipe and it uses barb fittings which will restrict flow and I find it a pain to push the fittings together and some situations then also require a metal pipe clamp around it to keep them from blowing apart.   I'm not sure what type of plastic those gray barb fittings are either.

Sylvia Bernstein said:

I've actually never done a comparison of these two pipe systems so I honestly don't know the answers.  Everything we've done has been with PVC because it is so easy to work with, cheap, and easy to find a gazillion kinds of fittings.  My husband calls it an adult Erector Set.  If HDPE is recyclable, and has everything PVC has, though, then maybe we would switch for future systems.

[Rick Op]

Sylvia Bernstein said:

Great perspective, Rick.  Thanks for that.  Other than a solids buildup issue (I'm assuming this is because of the way that PVC fittings fit vs HDPE), and the other unavoidable reasons you gave, are there any other reasons for using PVC over HDPE?  Like availability of size of tubing?  LIke availability and/or variety of fittings?  Cost?

It sucks that you are limited to 90-degree and straight and Tee fittings in the HDPE realm. If someone knows of a 45-deg I would love to know about it. So... It does best in long straight runs. This avoids the poo pileups that can occur at fittings.

I have my pump-to-growbed run in 1-inch HDPE. I may up that to 1.5 inch as I revisit it to install a sequencing valve.
"1-inch and smaller" accounts for the most available HDPE sizes, but 1.5 inch can be found at irrigation suppliers, Tractor Supply and at some Lowe/Depot stores. Anything smaller than 1-inch is gonna be problematic in aquaponics to say the least, so it's 1 or 1.5 inch HDPE and that means supply lines. For large gravity drains and manifolds, we're back to dealing with some flavor of PVC.

Nobody is mentioning ABS but there are some "collection" fittings available out there, and my impression is that ABS is between PVC and HDPE on the earth-friendly/earth-nasty scale.

With PVC, there's also a difference between solid-core and lighter formulations. Further wonking is possible on that distinction alone. But I have to use a little of everything to get my water to the various places it needs to go! I'm pretty happy when I can just make a connection that doesn't leak...

Rick

[TCLynx]

Very good Point There Rick about the differences of solid and foam core PVC.

This is mostly important when it comes to things like gravel guards.  If you were to take the foam sandwich core PVC and drill lots of holes in it and submerge it in your system......(can't say I know what's in the core), well, I don't want to do that.  So I try to get the solid PVC pipes and avoid the foam core stuff.

[Raychel A Watkins]

I  have no personal knowledge of the safety of PVC but the Friendlies got their systems certified organic using PVC.  If you are organic everything must be food safe.  We run our water we drink through copper and PVC.  i know there are problems with a lot of things but we have to use something.  CPVC is for hot water but it is very expensive and there are not so many fittings as PVC.  I don't think the water gets so hot it would leach out anything.  Your fish would cook if it got that hot.