4 Essential Things You Need To Know About Bulkhead Fittings For Plastic Tanks

Last Updated on June 4, 2022 by Guillermina

Learn all about the purposes of bulkhead fittings for plastic tanks.

Problems with how to connect plumbing to your aquarium? Or you may simply not be able to decide between the bulkhead and some other form of fittings. Let us help you. Bulkhead fittings for plastic tanks are not as simple as some other traditional fittings, and before buying you should know a few things. We will explain to you what it is and what its greatest features are.

Most importantly, whether you are an experienced plumber trying to be ready for your next project or you are just an aquarist faced with this task, bulkhead fittings for plastic tanks can be quite helpful.

What Is A Bulkhead Fitting?

Simply put, bulkhead fittings for plastic tanks are hard seals that are used as a water inlet for pipes and faucets, and among other things allow you to drill a hole into your aquarium tank. It is a fitting that will sit on a tank or drum or reservoir, and when it is in its place, it will allow liquids to flow.

Furthermore, bulkhead fittings for plastic tanks are of the greatest help to aquarists when they have to fill or drain their aquarium tank. They consist of a gasket, body, and locking nut that seals it in place, and are made of plastic (polyvinyl chloride) that can withstand temperatures up to 150 degrees Fahrenheit (65 degrees Celcius).

As for their purpose, they are mostly used as outlets for faucets, pipes, and hose spigots, but can actually be used in any type of application that involves large drums and the need to fill them.

 How do you attach a pipe to a plastic tank?

Bulkhead Fittings For Plastic Tanks Configurations

It is important to emphasize that all bulkheads intended for use in plastic aquarium tanks come in a Female x Female configuration and that all fittings or pipes will be attached to the interior of the bulkhead.

In addition, keep in mind that the threads on the outside of the bulkheads are made for the retaining nut to be threaded onto only. Accordingly, external ones will not accept any type of plumbing fittings.

These are the configuration types for bulkhead fittings for plastic tanks:

  • Slip x Slip
  • Thread x Thread
  • Slip x Thread
  • Thread x Slip

Fitting Requirements & Considerations

When purchasing bulkhead fittings for plastic tanks, it is necessary to pay attention to several things such as pressure, size, and material. Read more about it below.

Pipe Size

Bulkhead fittings for plastic tanks come in a variety of different sizes, some can be as small as 1/2 inch, while others can be as large as six inches. The size depends on your needs, ie the required hole size (and tank wall thickness).

 How do you install a bulkhead fitting on a poly tank?


In addition to coming in a multitude of sizes, they also come in a multitude of materials. They are mainly available in EPDM, FPM, or Neoprene. The material you choose depends on where the location of the bulkhead fitting is going to be, as well as the materials that will run through your fitting.

Since you will be using it in your aquarium that doesn’t leak corrosive substances, you don’t have to worry too much. Classic PVC should do its job pretty well.


Most bulkhead fittings for plastic tanks have a max pressure of about 150 psi, with the proviso that it can always have more or less than that. Accordingly, make sure that this fact is considered before buying to avoid getting stuck with a gasket that cracks under pressure.

Fitting Problems & Resources

As with everything else, damage can occur at any time, but fortunately, it is mostly repairable. Most of the issues that you will see with poorly operating bulkhead fittings for plastic tanks were made in the beginning, before buying the product.

As we have already mentioned, you must be sure to get the proper sizing, material, and quality of fitting, because only then will you be sure that everything will work fine. If you do this part of the process correctly, you are guaranteed to have high-performing bulkhead fitting for years to come.


Bulkhead fittings for plastic tanks are specially designed fittings meant to allow free flow of any form of liquids in an aquarium tank, drum drainage, and other plumbing connections. It allows you to transfer water from one side of an aquarium to the other. As for aquariums, they are used for drain and return pipes on your display tank but can be used for many other things as well.

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How Do You Install A Bulkhead Fitting On A Poly Tank?

Here are the simplest steps to install a bulkhead fitting on a poly tank: First slide the gasket over the body of the fitting and then insert the fitting body into the hole in the tank sidewall. Don’t forget to lubricate the threads on the fitting body with thread sealant. Then it is necessary to install a large nut on the outside of the tank. Hand tighten plus 1/4 turn with a wrench, try not to let it slip or spin. Finally, hydro test the tank for a minimum of 24 hours before placing it into chemical service, and you're done.

How Do You Attach A Pipe To A Plastic Tank?

Here are the basic steps for attaching a pipe to a plastic tank:

Make square cuts for strong PVC joints.
Sand the inside of the pipe.
Sand the outside of the pipe.
Make marks on the pipe and fitting.
Spread an even layer of solvent PVC cement outside and inside the PVC piping.
Push the pipe into the PVC pipe connectors fitting and twist the fitting.
Slide the pipe ends into the transition fitting, then carefully tighten the bands and finally seal the joint.


What Is A Bulkhead Tank Fitting?

Simply put, a bulkhead tank fitting allows you to transfer water from one side of an aquarium to the other, and can be used, among other things, for drains and return pipes on your display tank.

What Size Bulkhead Do I Need For My Aquarium?

If you want to choose the ideal bulkhead for your aquarium you need to measure the diameter of the hole in your aquarium and use a chart to match up the properly sized bulkhead for your aquarium.

Bulkhead Size


Maximum Hole Size


Minimum Hole Size


PVC Plumbing Size


1/2″ ABS Bulkhead






½” PVC or ½” NPT Threads


1″ ABS Bulkhead







1” PVC or 1” NPT Threads


2″ ABS Bulkhead




72mm/2.83″ 2” PVC or 2” NPT Threads


1″ Sch 80. Bulkhead






1” PVC or 1” NPT T