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For rainwater tanks, IBC totes, pumps, and general water-transfer systems, 2-inch cam lock fittings are the most common practical size. They move a useful amount of water without making the hose and fittings overly large.
However, cam lock size is a nominal size. A 2-inch cam lock does not mean every part of the fitting measures exactly 2 inches. You also need to match the connection type, thread, hose size, and fitting style before buying parts.
Why 2-Inch Cam Locks Are So Common
A 2-inch cam lock, also called a 2-inch cam-and-groove coupling, is widely used for moving liquids between tanks, pumps, hoses, and other equipment.
Manufacturers such as Dixon and Banjo offer extensive ranges of 2-inch cam-and-groove fittings, including threaded adapters, hose-shank couplers, elbows, caps, and reducing fittings.
For a rainwater system, 2 inches is useful because it works well with applications such as:
- IBC tote water transfer
- Larger rainwater tanks and cisterns
- Transfer pumps
- Tank-to-tank hoses
- Gravity-fed tank outlets
- Agricultural water systems
- Large garden or irrigation supply lines
That does not mean 2 inches is best for every system. A small rain barrel may only need a 3/4-inch or 1-inch connection, while a large cistern or high-flow pump may use 3-inch fittings.
Common Cam Lock Sizes
Cam-and-groove fittings are available in many nominal sizes. Common water-system sizes include:
| Cam lock size | Typical rainwater use |
|---|---|
| 3/4 inch | Small hoses and low-flow systems |
| 1 inch | Rain barrels and small pumps |
| 1-1/2 inch | Medium transfer lines |
| 2 inch | IBC totes, tanks, pumps, and general water transfer |
| 3 inch | Large tanks and high-flow pumps |
| 4 inch | Large commercial or agricultural systems |
Dixon lists cam-and-groove fittings from 1/2 inch through several much larger sizes, while Banjo's polypropylene range includes common sizes from 1/2 inch through 4 inches.
For a typical homeowner working with large water-storage containers, 2 inches is usually the first size worth checking.
What Does a 2-Inch Cam Lock Measurement Mean?
A cam lock size describes the nominal connection size, not the outside diameter of the complete fitting.
For example, Dixon identifies its size code "200" as a 2-inch cam-and-groove connection. The same fitting might have:
- a 2-inch cam lock connection
- a 2-inch pipe thread
- a 2-inch hose shank
But reducing fittings are also available.
You could have a fitting with a 2-inch cam lock on one end and a 1-1/2-inch hose connection on the other.
This is why measuring only the outside of an existing fitting can lead to the wrong replacement.
A 2-Inch Cam Lock Does Not Guarantee a 2-Inch Thread
This is one of the easiest mistakes to make.
The cam-and-groove side and the threaded side are separate specifications.
A fitting advertised as a 2-inch cam lock might connect to:
- 2-inch male pipe thread
- 2-inch female pipe thread
- 2-inch hose
- a different-size hose through a reducer
- an IBC tote thread through a separate adapter
Check both ends before ordering anything.
IBC Tote Connections Need Extra Attention
Many rainwater systems use IBC totes, and this is where size confusion becomes especially common.
Do not assume that an IBC outlet described as "2 inch" will accept an ordinary 2-inch threaded cam lock.
IBC valves can use several outlet designs and thread standards. The tote may require an adapter between its valve and the cam lock.
Before buying an adapter, identify:
- The tote valve outlet.
- The outlet thread type.
- The cam lock size you want.
- Whether you need a male adapter or female coupler.
If the existing valve has an unknown thread, measure and identify that connection rather than forcing a pipe-thread fitting onto it.
Cam Lock Types Matter as Much as Size
Cam locks use letters to describe how the two ends of the fitting are arranged.
The common configurations include:
Type A
Male cam adapter on one end and female pipe thread on the other.
Type B
Female cam coupler with cam arms on one end and male pipe thread on the other.
Type C
Female cam coupler with cam arms and a hose shank.
A hose shank is the ridged end that fits inside flexible hose.
Type D
Female cam coupler with female pipe thread.
Type E
Male cam adapter with a hose shank.
Type F
Male cam adapter with male pipe thread.
So asking for a "2-inch cam lock" is not quite enough. You might actually need a 2-inch Type C, 2-inch Type F, or another configuration.
Banjo, for example, offers 2-inch fittings across Types A, B, C, D, E, and F.
Which Two Cam Lock Parts Connect Together?
The basic connection is simple:
A male cam adapter fits inside a female cam coupler.
The female coupler has two cam arms. When the arms are pushed down, they lock around the groove in the male adapter and compress the gasket.
You do not normally connect:
- male adapter to male adapter
- female coupler to female coupler
Evaluating recommended camlock fittings for water tanks, pumps, and hoses helps understand required pump lift with suitable operating safeguards.
The fitting letters determine what connection is available on the opposite end.
For example, a common hose connection could use:
Type E male adapter → Type C female coupler
Both might be 2 inches, with each fitting attached to a 2-inch hose.
Should You Use 1-1/2-Inch or 2-Inch Cam Locks?
For a small water system, 1-1/2 inches may be enough.
For larger tank transfer, 2 inches is generally the more useful size because it allows a larger flow path and matches many water-transfer components.
But making the cam lock larger does not automatically increase your water flow.
Flow can still be limited by:
- the tank outlet
- the valve opening
- hose diameter
- hose length
- elbows and reducers
- pump capacity
- elevation difference
- downstream plumbing
For example, installing a 2-inch cam lock on a system that immediately reduces to a 3/4-inch garden hose will not make the garden hose behave like a 2-inch transfer line.
Should the Cam Lock Match the Hose Size?
Usually, yes.
A straightforward setup might use:
2-inch tank outlet → 2-inch cam lock → 2-inch hose → 2-inch pump inlet
Keeping the main transfer path the same size reduces unnecessary restrictions and makes replacement parts easier to understand.
Reducers are useful when equipment has different connection sizes, but adding several reducers can create needless complexity.
Choose the main line size based on the water flow you actually need rather than choosing a fitting simply because it is common.
Are All 2-Inch Cam Locks Interchangeable?
Standard cam-and-groove fittings are designed around established dimensions, so compatible 2-inch male adapters and female couplers are generally intended to connect.
Dixon states that its standard cam-and-groove couplers and adapters are made to interchange with products conforming to Commercial Item Description A-A-59326D. Dixon also notes that some less-common sizes do not have the same interchangeability standards.
Even when the mechanical connection fits, you still need to consider:
- fitting material
- gasket material
- water temperature
- pressure
- liquid being transferred
- thread type on the opposite end
For ordinary non-potable rainwater, polypropylene cam locks are commonly used because they are light and corrosion resistant. Other applications may use aluminum, brass, or stainless steel.
For drinking-water systems, do not assume a fitting is suitable just because it physically fits. Every water-contact component should be appropriate for the intended potable use as part of the complete treatment and plumbing system.
How to Find Your Existing Cam Lock Size
If you already have a fitting, look for a molded, stamped, or printed size first.
You may see markings such as:
- 150 for 1-1/2 inch
- 200 for 2 inch
- 300 for 3 inch
Dixon, for example, uses "200" to identify a 2-inch fitting in its ordering system.
If there is no marking, identify the fitting by more than one measurement.
Check:
- male adapter outside diameter
- female coupler opening
- hose inside diameter
- thread outside or inside diameter
- thread pitch
- fitting type
Do not identify pipe threads by diameter alone. A nominal 2-inch pipe thread does not measure exactly 2 inches across the outside.
Choosing a Cam Lock for a Rainwater System
Start with the equipment rather than the cam lock.
Follow the water path:
Tank → valve → adapter → hose → pump or destination
Write down the connection at each point.
For example:
- Tank valve: existing IBC outlet
- Adapter: IBC outlet to 2-inch male cam adapter
- Hose: 2-inch transfer hose
- Hose fitting: 2-inch female cam coupler
- Pump: connection sized for the pump inlet
This makes it much easier to spot an incompatible thread or unnecessary reducer before assembling the system.
Also make sure the hose, fitting, gasket, valve, and pump are suitable for the operating pressure. Never disconnect a cam-and-groove coupling while the line is pressurized. Banjo and Dixon both provide pressure and operating guidance specific to their fittings.
Frequently Asked Questions
What is the most common cam lock size for water?
For rainwater tanks, IBC totes, pumps, and general water transfer, 2-inch cam locks are one of the most common and useful sizes. Smaller systems often use 3/4-inch, 1-inch, or 1-1/2-inch fittings.
Are IBC tote cam locks usually 2 inches?
Two-inch connections are very common around IBC tote water-transfer systems, but the tote's actual valve outlet may use a different thread or connection standard. Identify the valve before buying a 2-inch cam lock adapter.
Will any 2-inch cam lock fit another 2-inch cam lock?
Standard-compatible 2-inch male adapters and female couplers are generally designed to mate. However, check the fitting standard, gasket, material, pressure limits, and the connection on the opposite end.
What is the difference between Type C and Type E cam locks?
A Type C has a female cam coupler with cam arms and a hose shank. A Type E has a male cam adapter and a hose shank. The two can be used together to make a quick-disconnect hose connection.
Is a 2-inch cam lock actually 2 inches across?
Not necessarily. Two inches is the nominal fitting size. The outside dimensions of the male adapter, coupler, threads, and body will be different from exactly 2 inches.
Is a larger cam lock always better?
No. The cam lock should fit the rest of the water path. A large fitting provides little benefit if the tank valve, hose, pump, or downstream plumbing creates a much smaller restriction.
What size cam lock should I use on a rainwater tank?
Match it to the tank outlet, required flow, hose, and pump connections. For larger tank-transfer systems, 2 inches is a common starting point. Small rain barrels and low-flow watering systems may work better with smaller plumbing.
