PVC Pipe

[swandriver]

We're always amazed that more boats are not plumbed with ordinary PVC pipe, but then again we never thought of using it either until we bought Morgan’s Cloud 16 years ago and found that her builder had used PVC pipe for almost all of her plumbing. Since then we have added several plumbing systems in PVC and modified existing ones.
Among the benefits are:

1. Economy. PVC pipe is dirt cheap. The total at the cash register after you buy several lengths of pipe, together with the fittings and glue to go with it, comes as a surprise—a pleasant one; particularly if your last stop was a yacht supply shop (chandlery).
2. Availability. Even a small corner hardware store has enough PVC plumbing fittings in stock for most jobs and the bounty in the bins of a large building supply store will let you build almost anything.
3. Flexibility. No, it does not bend, or at least not much, but the amazing variety of PVC pipe fittings allows you to solve some very vexing problems surprisingly easily. Want to connect a 2” line to a 1/2” line and then T off a 1” line? A quick trip to a hardware store and a bit of ingenuity and you are done.
4. Fast Assembly. With a little practice and a pipe cutter you can assemble a plumbing system amazingly quickly using PVC pipe. (You can cut the pipe with a saw, but it is time consuming and messy.)
5. Long Lasting. Even good quality hose only seems to last five years or so, but PVC pipe will last decades.
6. Impervious to Most Chemicals. You can flush a PVC pipe system out with muriatic (hydrochloric) acid; the quickest and, as far as I know, only effective way to get rid of the scale that builds up in head discharge lines. Don’t try that with hose.
7. Impervious to Odors. You can spend a fortune on sanitation grade hose and your holding tank system will still stink, but it won’t if you use PVC pipe.

One caution: We do not recommend PVC pipe for piping that is open to the sea and below the water line where a crack could sink you.

[GordMay]

Originally Posted by GordMay

... My 1984 C&C had PB plumbing, which hadn't leaked up until 2001. I still unconditionally advise against it's use.

Correction: My polybutylene plumbing failed at the hot water tank connection, in 1993, when it was 9 years old.

[David M]

PVC is too brittle. Use sanitation hose.

There are other good reasons why boat manufacturers do not use PVC for that application...as Gordon shows.

[Zednotzee]

I get the impression a lot of terms are being used interchangeably (& incorrectly) here.

The PB plumbing Gord refers to is polybutylene.

PVC is polyvinyl-chloride.

ABS, or Acrylonitrile butadiene styrene, is also commonly used in household sanitation plumbing.

These materials are all substantially different from one another.

Just because something has always been done a certain way does not automatically make that the best way to do things.

[osirissail]

Besides heat being very bad for Qest Polybutyl pipe - in the housing business it was too difficult to install correctly by the average worker. It was quick, which is why it caught on but as with any new product there wasn't sufficient information (history) of the product in actual use. What is sometimes a great engineering/lab idea, many times does not hold up out in the "real world." Another problem with Qest system was the degradation of the material as alluded to in other posts. Builders were burying it underground and in other enclosed environments. The particular formulation of Qest was "environmentally friendly" which mean biodegradable. And those installations also failed. Since the product is not really on the market anymore, getting it is not easy. The new material is available in marine stores.
- - As to using "pipe" versus "tubing" versus "hose" there are definite differences. The words "pipe" and "tubing" are frequently mixed up and used to mean one thing or the other. I use pipe to mean "rigid" - not easily bent such as the white PVC home plumbing pipe and CPVC home water supply pipe and rigid copper pipe. Tubing is somewhat more flexible like the risers for connecting your home water to sinks an

[jkleins]

Originally Posted by David M

PVC is too brittle. Use sanitation hose.

There are other good reasons why boat manufacturers do not use PVC for that application...as Gordon shows.

Steve Dashew would probably disagree. It seems he likes schedule 80 glued PVC for almost all plumbing applications in his boats. Take a look at his site at setsail.com and search for PVC and you will see some beautiful PVC installations for all sorts of plumbing needs. He even credits his use of PVC for keeping the head smell down in his boat when it is closed for long periods.
While you can certainly argue that he is wrong you can't make the statement that "boat manufacturers" don't use it when one who makes some of the most respected boats on the market does.

Jim

[osirissail]

I am also a fan of solid PVC pipe for sanitation purposes and its apparent ability to significantly decrease or eliminate "head" odors. However, my installation of rigid PVC pipe uses supports before and after every joint and elbow and every 12 inches (30cm) for long runs. Each support has a rubber wrapping around the pipe underneath the strap or support clamp. This allows a minimum amount of movement to mitigate shock loads and keeps the pipe from "whipping" or flexing due to boat motion.
- - Also it is important to know and follow the real gluing techniques and not the quickly procedures to ensure a full strength bond at each fitting. Just like glass plates and wine glasses, it they are properly stored and handled they will not break.
- - My philosophy on boat systems involves engineering and installing each system so that you could mentally grab the keel of the boat, turn it upside down and shake it - and nothing would - theoretically - come loose or break. As a cruiser you will be caught out there sometime or other in some really nasty seas and winds. You will really get an up close and personal experience of what it is like to be a cork in a washing machine. Having the insides of the boat come apart is not conducive to personal longevity.

[GordMay]

Originally Posted by David M

... There are other good reasons why boat manufacturers do not use PVC for that application...as Gordon shows.

What exactly did Gordon show, and where?

[DeepFrz]

I know that Kanter uses PVC pipe in their boats and they are a premium custom boat builder. Also I know that Nordhavn use it in their boats. So I think there have been some wrong assumptions stated here about boat builders not using PVC.

[rwidman]

Originally Posted by yardpro

I am a landscaper and work with pvc in our irrigation system installation. I was going to re-plumb the pressurized freshwater system in my boat with pvc. I was told that this was not an approved material...

is this true, if so why?
how about pex?
i am trying to get away from the clear reinforced hoses if i can.

I would not use PVC in a boat because it is relatively rigid and becomes somewhat brittle when it gets cold. It will also sag and bend it not properly supported and it gets hot. PVC cannot be used for hot water anyway.

PEX is fine if properly installed. Better yet is the water tubing manufactured and sold for use in boats. Marine stores have it and the fittings.