Waterproofing Wood/ making water tank out of wood?

montreal_newbie

Hello, I am working on a university project.
We need a mist-collection reservoir (environmental project). Because the budget is very limited, and only so many tools are available,
it was decided that we make it out of wood.

Please see attached diaghrams.
Everything is joined using 3" wood screw.
The water will drip to the bottom of the tank, and maybe go up 4-6inches at most, before it is sucked out.

using standard home depot construction lumber, and 1/2" plywood as a bottom.
Is there a way to waterproof this?
a method of sealing the wood joints to avoid leaks?
how long will it last?
Any help/advice is greatly appreciated,

Thank you!

pbacot

Nice model. I want it for my wife's planter box.

Water tanks and barrels generally take a different shape (round) and are designed so the wood swelling will force joints closed. In this model there's no reason for the joints to push tight and even if it holds water for a while it will tend to leak as the wood swells and shrinks. Also plywood by itself is not great around water. But any of the wood is fine if you want to cover it with fiberglass or some other waterproof finish. As in a boat you need to make the joints secure and cover with fibeglass webbing and resin. That's more cost and tools.

Is there a reason you are making this out of wood? Wood's expensive. Probably there is a container you can buy that would be cheaper. For something about this size, a rigid child's wading pool might work. But perhaps that is not environmentally appropriate technology. Recycling a metal farm animal feeder etc. might be.

Also you can use a tank liner, but I assume that is not what you were after either. Good luck.

montreal_newbie

thank you pbacot.

Fiberglass? can you please point me to a tutorial? I only find sub-woofer enclosure guides...
Wood expensive? yet is it, how else can I make this? Plastic mold - more expensive,
and trying to find alternatives such as child's wading pool, is virtually impossible because
we are pretty strict with it's sizing. Also having a single 2 meters x 2 meters, needs a cubevan to transport,
more cost..

what else can be fabricated to make a water tight container?

watkins

Why not line the interior with heavy duty polythene. Such material can be obtained from a builders merchant. The same approach is used when making garden ponds. This approach is cheap and cheerful too.

Regards,
Bob

montreal_newbie

Thanks watkins!
Heavy duty polythene seems very nice.
How do I go about attaching it to wood and joining it?
Any tips will help.

Thanks again!

montreal_newbie

Can I use Polythene tape, such as "1433 All Weather Tape"
Or is there a suitable technique to weld the joins in this type of tank?

alexschreyer

Don't forget that water pressure increases toward the bottom. Although this is not very deep, make sure that the wall/floor joint is tight. I would also add fillers (e.g. 2x2) into all inside corners and then screw the boards to them. That makes tighter corners and provides stability.

Also, don't be tempted to buy OSB (as shown on one of your images) unless you completely cover it.

dale

@montreal_newbie said:

Can I use Polythene tape, such as "1433 All Weather Tape"
Or is there a suitable technique to weld the joins in this type of tank?

If your budget allows you could use a polyethylene sheet that comes in various thicknesses, in your case say 6mm or less. You can rent a poly welder, which is like a sophisticated hair dryer, which you use to heat up the poly welding rod with hot air. I have built tanks that held hydroflouric acid (myself), so they had to be well done, and the process is quite easy to do. With this method you can also "spin" in a drain valve. Which is as it sounds you spin the valve with a drill till the friction melts the poly and forms a weld.
A good plastics shop can advise you.

pbacot

Fiberglass wood construction is best learned from boat builders.

But if you are open to buying or making a tank liner, I'd do that instead. Then the wood structure is merely a form for the liner. There are many types of materials from polyethylene, to vinyl or "Hypalon". Concerns: Is the water supposed to potable? How long do you need it to last. The end of the term? Commercially made tank liners have "bulkheads" to connect drain lines to, but you may be able to get the fittings for your homemade version.

The wood still needs to be somewhat moisture proof. If you use plywood be sure it is exterior grade or, better, marine grade. Many years ago I worked on an algae farm where we built all sorts of ponds with plywood and tank liners, including a large processing tank of plywood and epoxy paint (and Bondo). The latter was probably designed for a couple years at most. Prototypes were coming and going all the time.

dale

You have my curiosity piqued. Are you working on a fog fence, or dew harvester? Give us a little background. The shipping constraints seem to suggest something interesting as well.

Bep

I would try to get some used PE container that i could clean ,for example soap or shampoo factory's use them.

Greetings,

Bep