I’m launching a little balcony gardening project that involves water reservoirs. I don’t have much experience with these kinds of projects, so I need a little help.
Due to some dimensional constraints, I will need two regular plastic containers (your typical storage containers), and I was hoping to get away with only including a way to fill one of them. That means I will need to connect it to the other in some way. So I thought I would just drill a hole in both of them and stick a pipe between them.
- What is the best way to drill holes in plastic without risking any splitting?
- How do I make sure that the holes are water sealed afterwards? Can I glue around the pipe and plastic box?
Look up bulkhead fittings. Use them at work to connect chemical tanks together.
bulkhead fittings
Ah, I was struggling to find the English term for that. Yeah, those are best, but you can improvise one with some threaded connections and some cut-out rubber (taken from an old bicycle interior tyre for example) or (not nearly as good) teflon tape.
This is what you’re looking for.
Cheers, I’ll look into those! :)
Instead of glue, I’d recommend getting some silicone sealant. It’s pretty much designed for this sort of thing
Marine silicone is specifically formulated to be water tight (and safe for aquarium inhabitants). It can be found at specialty salt water aquarium stores.
Good idea, didn’t think about that!
I’m not sure of the scale here, but you might also consider using a hot knife to cut the holes rather than drilling, and flexible plastic tubing rather than a pipe
Would it be possible to maintain at least some water in both containers? If so, a simpler approach might be to try a siphon. Here’s an image showing a (way bigger) example, but the theory would be the same for your containers.
Thanks for the suggestion. I think it would be difficult to maintain water in both, and I don’t have too much leeway in terms of height differences either.
I would say for 1. melting instead of cutting is a sure way, but any kind of cutting that doesn’t deform the container too much usually also works. You can also take a small drill and make a series of holes in a circle and then cut it out from there.
As for 2. you need to experiment with the compatibility of glues with the plastic of the container. A two component epoxy glue will nearly always work, but is probably overkill. Another common method is to used rubber gaskets and screw on clamps of some sort.
P.S.: in some cases a simple siphon will also work if you can ensure it never falls dry.
Melting sounds like a good idea. What would you typically use to do it? A soldering iron perhaps?
When you say compatibility, do you mean in terms of adhesion, or are there other things I should be concerned about?
The proper way to cut the hole would be using a drill with a hole saw, drill in the center pilot bit like normal and then cut the actual hole with the drill running in reverse for this specific application. If you ran the saw forward the teeth of the hole saw will be far more likely to catch and crack the container.
Whatever method of cutting you use, make sure to clean up the edges with some sandpaper so there isn’t a rough edge.
A bulkhead fitting should have a rubber gasket that will seal properly without additional sealant, but a nice fat bead of clear silicone sealant will help if the spot you put the hole at isn’t a perfectly flat surface and the plastic doesn’t deform ideally when you tighten the fitting. Aquarium silicone would probably be ideal for planter use, bathroom or construction silicone can offgas harmful stuff for plants.
The sides of the container won’t be parallel to the ground, so a straight pipe will put strain on the container that will lead to a failure. You will probably want to use flexible hose to connect the two containers, but two 45 degree elbows at each end of ridgid pipe(so 4 total) can take the strain out once you play with the orientations.
Thanks for a great description!
A couple of questions:
A bulkhead fitting should have a rubber gasket that will seal properly without additional sealant
Since bulkhead fittings were suggested, I’ve been looking them up. The installation seems easy enough, but in all the videos I see I am stuck with a hole with threads on the outside, no one shows what comes next. What are the parts I would need for this? Do I need a join to connect the threads on the outside of each container?
The sides of the container won’t be parallel to the ground, so a straight pipe will put strain on the container that will lead to a failure. You will probably want to use flexible hose to connect the two containers, but two 45 degree elbows at each end of ridgid pipe(so 4 total) can take the strain out once you play with the orientations.
I didn’t really understand this. Do you mean there will be strain due to the downward force exerted by the weight of the pipe and water? I’m hoping to have the distance between the tanks as short as possible, and the diameter should also not be too big.
There are oodles of types of bulkhead fittings. The typical type have a threaded end that gets inserted into a hole from the outside and a nut with a flange tightens down and clamps a gasket to the inside surface.
The end outside of the container can have any number of means to attach a hose or pipe; like a barb, flange, thread, etc. For your application you will want a barbed bulkhead so you can just put a hose on there and don’t need to worry about the additional cost and work involved with rigid pipe.
As for the stain issue. The type of container you described leads me to believe it is a typical plastic storage box, almost all of those have a taper to the sides. So if you put a bulkhead fitting in it, the fitting will be tilted downward. You are looking to connect two containers, which will have both fittings pointed towards the ground and not straight at one another. Connecting them with pipe would require you to either force them in line(adding strain) or use angled pipe bends to get things to line up. So a vinyl tube would be better to connect the containers than a pipe.
Tube and barbs also have the benefit of being easier to connect across a short distance and ensure a watertight connection. I would recommend putting the tube on both sides first, then installing the bulkheads in the containers to make life easier and avoid damage when trying to press the tube on the barbs after the bulkheads are installed.
The size of the containers will dictate the diameter of the tube. A one gallon would probably be fine with a 1" tube, but a 30 gallon would do better with 2-3" diameter.
The end outside of the container can have any number of means to attach a hose or pipe; like a barb, flange, thread, etc. For your application you will want a barbed bulkhead so you can just put a hose on there and don’t need to worry about the additional cost and work involved with rigid pipe.
Ah, I’ve seen those kinds before, and that seems fairly simple. Thanks!
As for the stain issue. The type of container you described leads me to believe it is a typical plastic storage box, almost all of those have a taper to the sides.
Of course, now I understand what you meant! Yes, the boxes are slightly tapered, so that would be an issue.
Tube and barbs also have the benefit of being easier to connect across a short distance and ensure a watertight connection. I would recommend putting the tube on both sides first, then installing the bulkheads in the containers to make life easier and avoid damage when trying to press the tube on the barbs after the bulkheads are installed.
Great tips, noted! Now I’ll have to figure out where I can buy these locally.
Thanks again for great help!
I have seen them at larger hardware stores. I would check hydroponic supply stores, if you have those. Farm supply stores and gardening stores might be good options as well.
Look for a hardware store. Even if they don’t carry it, a local place might be able to order one for you, or at least point you in the right direction. If you can find someone who’s more plumbing focused, it might be easier, but I don’t know how many of those there are left these days.
If you use a hole saw I would recommend you drive the drill bit in reverse. It will make a cleaner cut and in general is just nicer to do with plastics.
You could buy some quick fit hose fittings with o-rings and use those to attach the pipe. It’ll work just fine.
Any hot metal thing will do. You can combine the melt with the drill method by poking a series of smaller holes with a hot nail. Better do it in a ventilated space though… a balcony will do ;)
And yeah, some glues just don’t stick well to certain types of plastic. You can try roughen the surface up a bit with sand-paper but it will not always work and having a leak because you accidentally slightly moved a container is annoying. IMHO the rubber-gasket way is the most durable way of doing it.
Your local DIY shop should have pipe fittings and PVC cement for any configuration that you need. Grab a hack saw or pipe cutter for the piping and use a hole saw to avoid splitting the containers.
Our local DIY (Lowe’s - US) generally offers classes for whatever you’re likely to be building at any given time of year. It might be worth a phone call to ask.
