PVC Pipe

[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.

[GordMay]

PVC & PEX are both fine, as plastics which comply with National Sanitation Foundation or FDA stadards for potable water.

[yardpro]

thanks for the reply..
i did not se why they would not work, and with my MUCHO experience with both, it would be very easy for me to run pvc to all my needed fixtures.

i was told that if i had my boat surveyed, they would notate it and it would have to be fixed for insurance as it does not meet some marine standard...

was this guy full of it or what?

[Drew13440]

Full of it.

[GordMay]

ABYC* Standard H-23 — Installation of Potable Water Systems for Use on Boats
Specifies that plastics certified for use with potable water are acceptable.

* American Boat and Yacht Council

[DeepFrz]

My understanding is that it is fine as long as you use a flexible section anyplace you may get flexing. Most of the major boat builders now use PVC in their water/waste systems.

[S&S]

Originally Posted by Drew13440

Full of it.

Ditto. PVC (or CPVC) if you can support the pipe, else PEX.

[osirissail]

The problem with PVC is not with whether it is certified for potable water but what happens to the pipe when installed in a boat. The installation has to be such that the pipe is securely supported and restrained to prevent abnormal flexing and vibration caused by the boat moving through the seas. If the pipe is not properly supported and held in place it will "slap" and move with the flex and vibrations resulting in pipe failure, joint failure or fitting failure. Also PVC will fail if the water inside freezes.
- - polybutyl (used to known as Qest) plastic is used in RV's and boats as it is softer and much more flexible to absorb the vibrations of boats underway.
- - Fittings, joints and elbows have to be glued properly, not the normal incorrect methods commonly used by home owners. All must be supported.
- - One major problem with using PVC pipe in boats has nothing to do with all the above but has to do with the fact that you cannot bend it enough to snake it through, up and around, and over existing boat structures like you can with flexible pipe/hose.
- - In every case potable water pipe/hose needs to be totally opaque to light. Light and sunlight reaching the water inside the translucent or transparent pipe/hose will cause black organic growth inside the pipe/hose. Not pretty and not cleanable.

[swandriver]

If using PVC; lets say Qest would one choose a compression fittings or would glued be preferrable?

[GordMay]

Do NOT use Quest "polybutylene" pipe. !!!

➥ Let me google that for you

[colemj]

Probably not a problem - They don't make it anymore.

Mark

[osirissail]

Originally Posted by GordMay

Do NOT use Quest "polybutylene" pipe. !!!

Not quite true - and for the rest of the story - There is nothing wrong with the Qest system** as I have installed and used it for over 20 years in both RV's and boats.
- - The ** is important as you should not use it unless you KNOW what you are doing. Polybutyl pipe is very good for installations where flexibility is needed and freezing is a problem. The pipe will not burst when frozen and thawed. The problem with the Qest/Polybutyl is you cannot glue it. For mass installation where time is a cost factor the system was originally sold using "crimp" fasteners which weakened and corroded over the years and resulted in significant water leaks. So the system was withdrawn from the home/housing market. The failures were all attributed to improper installation. Those who have had so-called "professionals" work on their boats know all about improperly done installations of this or that.
- - Compression fitting have always **if properly installed** been secure and mine have lasted now for almost 20 years. If exposed to excessive heat over time (e.g. up close and personal to a water heater) the oils that keep the polybutyl soft and flexible evaporates and the fitting will fail.
- - The Qest brand is just about gone from the home repair (e.g. Home Depot) market but remains strong in the RV market. You would be hard pressed to find the material these days.
- - In the marine market other manufacturers, Sea-Tech and Whale are marketing a white translucent with similar push on/compression type fittings - they are much more elegantly engineered for D-I-Y use - and of course, with a higher price.
- - As with a lot of products in the professional markets, how the system is installed and maintained makes a world of difference. The same bottom paint system will work great if applied expertly or will fail to do its job if it is slapped on by somebody who does not know how to do it correctly.
- - In boats you have very few choices these days for potable water supply. Pipe/hose are the options with most after-market going for white vinyl hose. I have not been to a boat show in about 4 years but friends with new upscale boats are using the white marine Sea-Tech/Whale systems version pipe. Copper is problematical as it is difficult to install after the boat is complete and is subject to corrosion. Normal PVC and CPVC pipe is really too brittle for the high vibration, flexing and slamming that boats are subject to in the oceans.
- - You really need to know what you are doing with just about any system except vinyl hose and the new Whale/Sea-Tech high priced pipe. Although boats appear to be very similar to "house" installations - they really are not. They are probably more akin to aircraft installations. Vibration, high shock loads, support/restraint for inverting of the vessel and the highly corrosive environment of the oceans make the installation design and techniques more critical. And more expensive.

[jkleins]

Whenever this topic is brought up I hear a lot about the movement, shock loading, etc of boats and how they are so sensitive and how you have to be very careful. Yet I see this material in just about all motorhomes and trailers and it seems to standup just fine with little worry. I can assure you my motorhome has much more abrupt and harsh movement then my boat so I wonder if most of the talk is just unfamiliarity with the material and the "newness" of it's use in boats.

I was looking at my holding tank pipes in the motorhome and not one of the waste pipes has any type of flexible coupling as it passes around corners or through the body. They are fairly medium thickness black pipe and yet you hear all sorts of warnings if you even think about using anything like this in your waste system on a boat without complicated flexible connectors, etc.

What is really different in these two systems? Are we just too paranoid on boats? Are there forces that I am not feeling that the pipes are? Are we just real slow adopters?

Just wondering.

Jim

[GordMay]

Faulty installation is merely one cause of failure in polybutylene plumbing systems.
Chlorine, added to water supplies, deteriorates PB causing brittleness, weakness, or holes in the pipes.
While scientific evidence is scarce, it is believed that oxidants in water supplies, such as chlorine, react with the polybutylene piping and acetal fittings causing them to scale and flake and become brittle. Micro-fractures result, and the basic structural integrity of the system is reduced. Thus, the system becomes weak and may fail without warning causing damage to the building structure and personal property. Because the pipe deteriorates from the inside, it’s virtually impossible to visually detect installation problems, prior to failure.

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

[donradcliffe]

I just redid the house plumbing with pex, and would use it for any boat job. It will be around for a long time, and the fittings and hose are now available at Home Depot.