As an affiliate, we may earn a commission from qualifying purchases. We get commissions for purchases made through links on this website from Amazon and other third parties.
Another common name for a bulkhead fitting is a tank fitting or tank connector. You may also see terms such as through-wall fitting, through-tank fitting, or bulkhead connector.
All of these names usually describe a fitting that passes through the wall of a tank, barrel, or container to create a sealed connection for a pipe, valve, hose, or other plumbing part.
What a Bulkhead Fitting Does
A bulkhead fitting creates a plumbing connection through a hole in a container wall. In a rainwater system, it may be installed on:
- Rain barrels
- IBC totes
- Water storage tanks
- Cisterns
- Small header tanks
The fitting normally has a threaded body, a gasket, and a nut. The body passes through the tank wall. Tightening the nut presses the gasket against the wall to help make a watertight seal.
For example, you might install a bulkhead fitting near the bottom of a rain barrel and attach a valve to it. The fitting lets water leave the barrel without relying on a hose pushed through an unsealed hole.
Other Names for a Bulkhead Fitting
Terminology varies by manufacturer, plumbing supplier, and region.
Tank Fitting
Tank fitting is one of the most common alternative names. It is a broad term and may include bulkhead-style fittings designed specifically for water tanks.
Check the fitting design rather than relying only on the name.
Tank Connector
A tank connector is another common term. It usually describes a fitting that connects pipework through the wall of a tank.
Some suppliers use "tank connector" and "bulkhead fitting" almost interchangeably.
Through-Wall Fitting
A through-wall fitting describes how the part is installed. It passes through the wall of a barrel, tank, or other container.
This term can also be used for fittings intended for equipment or structures other than water tanks, so check the intended application.
Through-Tank Fitting
A through-tank fitting is a more specific version of the same idea. It refers to a connection that passes through a tank wall and seals around the opening.
Bulkhead Connector
A bulkhead connector is essentially another way of saying bulkhead fitting. Depending on the supplier, the term can refer to plumbing, pneumatic, hydraulic, or electrical connections. Make sure you are looking at a fitting designed for liquids when building a rainwater system.
Is a Uniseal the Same as a Bulkhead Fitting?
No. They can perform a similar job, but their construction is different.
A traditional bulkhead fitting normally has a rigid threaded body, gasket, and retaining nut.
A flexible pipe seal, often sold as a pipe-through-tank seal, uses a rubber-like seal around the pipe instead. The pipe passes directly through the seal.
Both can create tank penetrations, but their installation requirements and pipe compatibility differ.
Do not assume that a hole cut for one type will fit the other.
What to Check When Buying One
The name matters less than whether the fitting matches your system.
Connection Size
Check the actual pipe or hose connection size you need. A fitting described as 1 inch, for example, does not necessarily require a 1-inch hole in the tank.
The required hole is usually larger than the nominal plumbing connection.
Follow the fitting manufacturer's hole-size instructions instead of guessing.
Thread Type
Evaluate key facts about the different types of bulkhead fittings to verify the choice within the overall harvesting system.
Check whether the fitting uses the same thread standard as the valve, pipe adapter, or other part you plan to attach.
Two fittings can both be described with the same nominal size while having incompatible threads.
Tank Wall Thickness
Bulkhead fittings have a limit on how thick a wall they can pass through. This matters with thick plastic tanks, insulated tanks, and some reinforced containers.
Gasket Material
The gasket must be suitable for the water and conditions in which it will operate.
For outdoor rainwater tanks, consider exposure to temperature changes and the intended water use.
If stored rainwater will be part of a drinking-water system, every wetted component needs to be selected as part of a suitable potable-water system. A fitting alone does not make collected rainwater safe to drink.
Inside Access
Many traditional bulkhead fittings require access to both sides of the tank wall during installation.
That can be easy with an open rain barrel but much harder with a large enclosed cistern.
Before drilling, make sure the fitting can actually be assembled and tightened in the chosen location.
Bulkhead Fitting vs. Tank Adapter
You may also see the term tank adapter.
Sometimes this means a bulkhead-style fitting. Other times it refers to a different adapter designed to connect to an existing molded or threaded tank outlet.
Check the product's installation method.
If the fitting passes through a new hole in the tank wall and seals that opening with a gasket or similar seal, it is performing the job normally associated with a bulkhead fitting.
The Name Matters Less Than the Fit
When searching for a bulkhead fitting, useful terms include:
- Bulkhead fitting
- Tank fitting
- Tank connector
- Through-wall fitting
- Through-tank fitting
- Bulkhead connector
Do not choose one based on the name alone. Check the connection size, thread type, required hole diameter, tank-wall thickness, gasket position, and intended use.
Those details determine whether the fitting will actually work with your rain barrel, IBC tote, cistern, valve, or pipe.
Frequently Asked Questions
What is the most common alternative name for a bulkhead fitting?
Tank fitting and tank connector are two of the most common alternatives. The exact wording varies by supplier.
What does a bulkhead fitting do on a rain barrel?
It creates a sealed connection through the barrel wall. It can provide an outlet for a valve, hose adapter, overflow pipe, or other plumbing connection.
Is a bulkhead fitting the same as a tank connector?
Often, yes. Some suppliers use the terms interchangeably. Always check the actual design and specifications because naming is not standardized.
Is a bulkhead fitting the same as a grommet?
No. A bulkhead fitting normally has a rigid body, gasket, and retaining nut. A grommet or flexible pipe seal usually seals directly around a pipe passing through the tank wall.
Can I use any bulkhead fitting on an IBC tote?
Not necessarily. Check the tote wall, fitting size, hole requirements, thread type, and whether you can reach the inside of the container to install the fitting. Using the tote's existing outlet is often simpler when it suits the system.
What size hole do I drill for a bulkhead fitting?
Use the hole diameter specified by the fitting manufacturer. The hole is normally larger than the fitting's nominal pipe size, so do not choose a hole saw based only on a label such as 3/4 inch or 1 inch.
Should the gasket go inside or outside the tank?
Follow the fitting manufacturer's instructions. The correct gasket position depends on the fitting design. Installing seals in the wrong location can cause leaks.
