PVC pipe for drinking water

[Paul S]

Is it safe to use pvc pipe for storage of drinking water? (Naturally after cleaning it super well)

My idea may sound kinda stupid, but I would like to use the space under the stern berth to store drinking water. It is in the idea stage now, but it might work.

The berth is about 6' long, If I can get, say 5-10 6' lengths of 3-5" pvc pipe, manifolded together under the rear berth, I calculate I can store about 20-30+ gallons of water, give or take.

The space under the rear berth rarely gets used on our M. I can't find a water tank that is that thin.

I figure PVC pipe is super cheap, easy to work with and durable.

I am, of course, open to other ideas to get water storage under the rear berth(s), but this seems like a plausable project. As much as I like the flexible water storage tank, it just takes up valuable real estate under the port seat, and is just a hair too small (have the 13 gallon unit)


Paul

[DLT]

PVC does not present a health hazard that I am aware of. I believe it is used all the time for water pipe. However, that idea seems like a rather heavy/bulky solution... Not to mention the venting issues that come with rigid tanks.

I was thinking I might eventually go with multiple plastimo flexible tanks. They make ones big enough to handle most drinking water needs. But, there are a couple of concerns:
1 - they expand when filling, such that they would likely press too hard against that middle support under the rear berth.
2 - they could be a source of some instability, with the weight of the water just sloshing around.

Using multiple smaller tanks should minimize both issues...

[Paul S]

PVC does not present a health hazard that I am aware of. I believe it is used all the time for water pipe. However, that idea seems like a rather heavy/bulky solution... Not to mention the venting issues that come with rigid tanks.

I was thinking I might eventually go with multiple plastimo flexible tanks. They make ones big enough to handle most drinking water needs. But, there are a couple of concerns:
1 - they expand when filling, such that they would likely press too hard against that middle support under the rear berth.
2 - they could be a source of some instability, with the weight of the water just sloshing around.

Using multiple smaller tanks should minimize both issues...

I have a small plastimo, but it really plumps up when filled, plus the filler and drain would certainly poke up a lot. Not sure you could fill it and still have reasonable volume. Maybe the 40 gallon one might work, 27" wide, 55 long (at $133 WM). As you mentioned..the potential instability might be a problem. Not sure, but might be.

The PVC wight would certainly be minimal compared to the weight of the water (200-250#). With the multi tube idea, it should minimize side to side sloshing. I guess you could put some check valves in to let the water down, but not up the tubes).

Venting should be easy to deal with. Have a vent to the outside when filling, and an auto-vent to replace the air as you use the water

Paul

[Randy Smith]

I like the idea...use black PVC pipe as it will help to keep algea and other "things" from growing........this really has possibilities if someone needed more water...very creative......and could be "worked" to make use...... Randy

[Mark Prouty]

According to the link, vinyl chloride monomer (VCM) was a problem prior to 1977.

http://www.vinylinfo.org/environment/ru ... facts.html

I've always used PVC only for waste water.

Baffling would be a consideration.

[Randy Smith]

My parents have water out of a natural spring...they put the system in 1971- a 1/2 mile of black pipe...still in use today...they live on the Oregon coast at Coos Bay...it really is good water....a little muddy after a good rain storm

[Chip Hindes]

If I can get, say 5-10 6' lengths of 3-5" pvc pipe, manifolded together under the rear berth

I think your plan is unrealistic.

5" pipe can hold water at the rate of roughly one gallon per foot. So 5 ea 10' pipe is 50 gallons, a realistic amount. 3" pipe is only one gallon per just under three feet; 50 feet is just 18 gallons, 100 feet is 36. Certainly eighteen gallons of water in 50 feet of pipe is pretty worthless; 36 is reasonable but at how much trouble?

Unless the M is way different than the X, I don't see you getting even one 10' length of 5" rigid pipe under the floor of the v-berth, let alone 5 lengths. You certainly can't do it through the existing small access hatches. 3" pipe may flex enough to jam a few lengths in, but 10 lengths? I think not.

You can't pump water into or out of a dead end pipe, so they'll have to be somehow connected at both ends: ten to twenty t-fittings? How do you get access to both ends of the pipe under the foor after you get them in there? If you start mixing the diameters you'll create a true nightmare. Each high spot has to have a vent, and you can only draw water from a low spot. With a pipe manifold assembled under the berth floor, I can't imagine you can do it with single high spot and a single outlet

Why do you think multiple tubes will minimize sloshing? Unless you've got some kind of baffle system, you'll have sloshing.

The Plastimo tanks are designed to carry their advertized capacity when they're only 4-7" tall; it's only when they're overfilled that they blow up like big sausages and start pressing against stuff. For instance, a 39 gal Plastimo is only 27.5" x 55" and properly filled just over 6" tall. The fill spout is right angle and takes up almost no space, and they don't have to be vented. I have one of these under my and forward dinette seat and it works great.

[Frank C]

Paul, it would be cheap enough to mock up something in 3 or 4 inch pipe, but the necessary fittings are costly. Still, you can always return them if you're only dry fitting. Maybe worth a stab ...

but, seems to me that under the cockpit is about the worst possible place to add 250 pounds, from the standpoint of hull performance. I think you could get several 5' lengths under the v-berth, but the dry fitting might reveal a problem.

Those PVC connectors and fittings will demand lots of radius space, dictating lots of lost capacity within the available cubic space. I doubt you can connect two lengths of that big pipe and also have them lie tangent to each otther? You might ameliorate the vacant spaces by inter-stacking two manifolds. It's a very interesting idea if you've got the time to experiment.

[Paul S]

The M seems (at least ours) seems to lean a bit forward (bow down a hair) which is why I was thinking about adding weight under the stern berth.

I think the big ass plastimo tank will be the way to go in the long run...but I was concerned about loss of volume since it wouldn't be able to plump up...and the cost.

I was tossing around the idea of the pvc pipe..I didn't work out all the engineering around it..like i said it is in the idea stage...I am sure a couple well placed check valves could control the sloshing around if it were to be built.

Paul

[wtelliott]

Actually, PVC is not suitable for drinking water. The plastic piping in homes for drinking water is CPVC. The PVC (cream colored) and ABS (black in color) are used solely for drain/waste lines. IMHO, the flexable containers that are on the market would be safer and I don't see why they could not be joined together with tees and flex tubing yielding the same result. Not only that, but they would minimize the sloshing around mentioned earlier.

[nedmiller]

CPVC should be used for hot water, but (small diameter) PVC can be used for potable water if marked with NSF-PW or NSF-61. Drinking water lines should not use PVC made before 1977 (not likely now!) or any plastic pipe not so marked or marked with NSF-DWV.

[craiglaforce]

I saw a documentary a few years ago about the dangers of flexible plastics on health.

The claim was that the plasticizer that was added to make the plastic flexible, would slowly leach into the water or milk or peas or individually wrapped cheese slices (fats like milk and cheese were the most dangerous, since they were more "like" the plasticizer molecules, increasing solubility.) Anyway, the plasticizer acts like a hormone in humans, supressing testosterone and increasing estrogen levels.

They drew a broad claim that this might be what has caused the dramatic lowering of the sperm counts and motilities in the last 20 years.