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The best way to attach PVC pipe to a rain barrel is to install a bulkhead fitting through the barrel wall, then connect the PVC pipe to the threaded or slip-fit side of that fitting. Do not simply glue PVC pipe into a hole cut in the barrel. PVC cement does not reliably bond PVC pipe to the polyethylene or similar plastic used for most rain barrels.
A bulkhead fitting gives you a solid connection, a gasket to help prevent leaks, and a proper fitting for attaching the pipe.
What You Need
The exact parts depend on your barrel and pipe size, but a typical installation uses:
- PVC pipe
- Bulkhead fitting sized for the pipe
- PVC threaded adapter or slip adapter, if needed
- Rubber gasket supplied with the bulkhead
- Hole saw sized for the bulkhead fitting, not just the PVC pipe
- Drill
- Deburring tool, utility knife, or fine sandpaper
- PVC primer and cement for PVC-to-PVC joints
- Thread sealant approved for the intended water use if threaded PVC connections are used
A bulkhead fitting is a fitting that passes through the wall of a tank or barrel. It has a gasket and retaining nut that clamp against the wall to create a sealed connection.
Check the fitting manufacturer's required hole diameter before drilling. A 1-inch bulkhead fitting, for example, usually needs a hole larger than 1 inch because the body of the fitting must pass through the wall.
Choose the Right Location
Decide what the PVC pipe will do before drilling the barrel.
Bottom Outlet
Put the fitting near the bottom if the pipe will:
- Feed a garden line
- Connect to another storage tank
- Supply a pump
- Drain the barrel
Leave enough space below and around the fitting for the bulkhead nut and any pipe fittings.
Avoid placing the hole extremely close to the bottom edge. The curved transition between the barrel wall and base may prevent the gasket from sitting flat.
Overflow Connection
Install the fitting near the top if the PVC pipe will carry overflow water away from the barrel.
Keep the overflow below the very top of the barrel so water can enter the overflow pipe before reaching the lid or other openings.
The overflow pipe should also be large enough for the amount of water entering the barrel. A small pipe can become the restriction during heavy rain.
Connecting Two Barrels
A bulkhead fitting can also connect PVC between barrels.
For barrels connected near the bottom, try to place the fittings at the same height. Uneven fittings can make the plumbing harder to align and may put extra force on the barrel walls.
Make Sure the Barrel Wall Is Suitable
Bulkhead fittings seal best against a reasonably flat section of wall.
Many rain barrels are round, so some curvature is unavoidable. Small fittings can often seal successfully on gently curved walls, but large fittings on sharply curved surfaces can be difficult to seal.
Also avoid:
- Ribs
- Molded seams
- Raised lettering
- Deep curves
- Damaged plastic
- Areas where you cannot reach the retaining nut
Some bulkhead fittings must be installed from inside the barrel. Make sure you can actually reach the installation area before drilling.
How to Attach PVC Pipe to a Rain Barrel
1. Empty the Barrel
Drain the barrel before drilling.
Working on an empty barrel makes it easier to control the drill and keeps plastic shavings out of stored water.
Clean the area where the fitting will be installed.
2. Mark the Hole
Place the fitting against the barrel and confirm that there is room for:
- The fitting body
- Gasket
- Retaining nut
- PVC adapter
- Pipe
Check both the inside and outside of the barrel.
Mark the center of the hole.
3. Drill the Correct Size Hole
Use the hole diameter specified for your bulkhead fitting.
Drill slowly and keep the hole saw as straight as practical. Excessive pressure can distort thin barrel walls or cause the hole saw to grab.
Remove loose plastic after drilling.
The edge should be smooth, but do not enlarge the hole unnecessarily. A hole that is too large may prevent the gasket from sealing correctly.
4. Install the Bulkhead Fitting
Follow the gasket arrangement supplied by the fitting manufacturer.
A common design has the gasket against the flange side of the bulkhead, but fittings are not all built the same way. Do not move the gasket to another side simply because another installation used that arrangement.
Insert the fitting through the hole and install the retaining nut.
Tighten it enough to compress the gasket evenly.
Do not overtighten it. Excessive tightening can:
- Distort the gasket
- Warp a thin barrel wall
- Damage the threads
- Crack some fittings
The goal is even gasket compression, not maximum possible tightness.
Connect the PVC Pipe
The connection method depends on the bulkhead fitting.
Threaded Bulkhead
A threaded bulkhead usually requires a matching threaded PVC adapter.
For example, the connection may look like:
barrel → bulkhead → threaded PVC adapter → PVC pipe
Use a thread sealant that is compatible with the fitting materials and intended water use.
Do not compensate for mismatched threads by forcing the adapter tighter. Plastic threaded fittings can split when overtightened.
Slip or Socket Bulkhead
Some fittings accept PVC pipe or a PVC fitting directly into a socket.
PVC primer and solvent cement may then be used according to the fitting manufacturer's instructions if the socket is made for solvent-welded PVC.
PVC cement chemically joins compatible PVC parts. It should not be used as a substitute for the gasket where the fitting passes through the barrel.
Support the PVC Pipe
One of the easiest ways to create a leaking barrel connection is to let a long PVC pipe hang from the bulkhead.
PVC can place considerable leverage on the barrel wall, especially when the pipe:
- Is long
- Is full of water
- Has valves attached
- Runs horizontally
- Gets bumped
- Moves as the ground settles
Support longer pipe runs independently with suitable clamps or supports.
For installations where movement is likely, a short flexible section between the barrel and rigid PVC may reduce stress on the bulkhead. Make sure the flexible hose and fittings are suitable for the pressure, water use, and outdoor conditions involved.
Test the Connection Before Finishing the Plumbing
Add some water to the barrel and inspect the bulkhead.
Look closely around:
- The gasket
- Bulkhead threads
- PVC adapter
- Solvent-welded joints
A dry paper towel held below the fitting can make a slow leak easier to spot.
If the bulkhead itself leaks, draining the barrel and correcting the gasket position is usually better than smearing sealant around the outside.
External caulk should not be used to hide a poorly installed bulkhead connection.
Connecting PVC to a Rain Barrel Spigot
If the barrel already has a threaded outlet, you may not need to drill another hole.
You may be able to install a PVC adapter on the existing outlet.
Regarding bulkhead fitting installation steps, evaluate upkeep requirements that affect future reliability.
Before doing this, determine:
- Thread type
- Thread size
- Whether the outlet can support rigid pipe
- Whether the existing fitting is securely attached to the barrel
Do not assume that an outlet described as "3/4 inch" automatically accepts every 3/4-inch plumbing fitting. Hose threads and pipe threads are different.
A garden-hose connection generally uses hose threads. PVC plumbing commonly uses pipe threads or solvent-welded sockets. An adapter may be required between them.
Should You Use a Uniseal Instead?
A Uniseal-style flexible tank seal is another way to pass PVC pipe through some plastic tanks.
The pipe pushes through a rubber seal installed in a correctly sized hole.
These seals can work well where their installation requirements are met, but a bulkhead fitting is often easier for beginners because it provides a threaded or socket connection and mechanically clamps to the barrel wall.
Use the hole size and pipe dimensions specified by the seal manufacturer. Small differences in hole size can affect whether these fittings seal correctly.
How to Keep the Connection From Leaking
Most leaks come from a few common problems.
Wrong Hole Size
A hole that is too large may not give the gasket enough surface to seal against.
Always size the hole for the bulkhead, not the nominal PVC pipe size.
Gasket on an Uneven Surface
Ribs, seams, and tight curves can prevent even gasket compression.
Move the connection to a smoother part of the barrel when possible.
Overtightened Bulkhead
More tightening does not always make a better seal.
Overtightening can squeeze or distort the gasket.
Unsupported Pipe
Rigid PVC can pull sideways on the fitting.
Support long runs separately rather than making the barrel carry their weight.
Incorrect Thread Connection
Pipe threads, hose threads, and other thread standards are not interchangeable.
Use adapters designed for the fittings you actually have.
PVC Pipe Size Matters
Choose pipe size based on what the pipe needs to do rather than simply matching whatever fitting is convenient.
For a basic garden outlet, a relatively small pipe may provide enough flow.
Overflow plumbing is different. It may need to move water rapidly during a storm. An undersized overflow can allow the barrel to fill faster than water can escape.
Connections between multiple barrels also benefit from adequate pipe size because small connections can restrict how quickly water levels equalize.
Remember that the smallest opening in the system often becomes the main flow restriction.
If the PVC Pipe Will Feed a Pump
A pump connection needs more planning than a simple gravity-fed garden outlet.
Consider:
- Pump inlet size
- Required flow rate
- Suction conditions
- Pipe length
- Number of elbows
- Shutoff valves
- Strainers
- Dry-run protection
Flow rate is the amount of water moving through the system over time, commonly measured in gallons per minute.
A small barrel outlet or narrow adapter can restrict a pump even if larger PVC pipe is installed after it.
Follow the pump manufacturer's inlet and piping requirements rather than reducing the pipe simply to match an existing small barrel spigot.
Protect Outdoor PVC From Freezing
Water trapped inside PVC can freeze and expand.
In freezing climates, design the connection so exposed plumbing can be drained or otherwise protected appropriately before freezing conditions.
Pay special attention to:
- Valves
- Low spots
- Pumps
- Filters
- Horizontal pipe
- Fittings directly attached to the barrel
Do not assume that wrapping exposed PVC alone will prevent freeze damage.
The barrel itself also needs a winter plan appropriate for its material, location, and climate.
Consider the Intended Water Use
For garden irrigation and other non-potable uses, a properly installed bulkhead and PVC connection can provide a simple way to move collected rainwater.
Non-potable means water that is not intended for drinking.
If the system will supply water intended for drinking, the plumbing connection is only one small part of the safety requirements. Roof runoff should not be assumed safe to drink.
Drinking-water use requires a suitable collection system, appropriate treatment stages, maintenance, current water testing, and compliance with applicable local requirements. Use components rated for the intended water service, and get qualified help when designing a potable rainwater system.
A Simple Connection Example
For a gravity-fed garden line, a typical arrangement might be:
rain barrel → bulkhead fitting → PVC adapter → short PVC pipe → shutoff valve → irrigation line
For an overflow:
rain barrel → upper bulkhead fitting → PVC adapter → PVC overflow pipe → safe discharge location
The exact adapters will depend on whether the bulkhead has male threads, female threads, or a slip socket.
Buy the bulkhead first. Then choose the PVC adapter around the connection provided by that fitting.
Frequently Asked Questions
Can I glue PVC pipe directly to a plastic rain barrel?
Usually, no. Most rain barrels are made from plastics such as polyethylene, while standard PVC cement is made for compatible PVC plumbing parts. Install a bulkhead fitting or another tank fitting designed to create a mechanical seal through the barrel wall.
What fitting should I use to connect PVC to a rain barrel?
A bulkhead fitting is usually the simplest choice. Select one that matches the PVC size and connection type you want, then drill the hole diameter specified by the fitting manufacturer.
Does the gasket go inside or outside the rain barrel?
It depends on the bulkhead design. Many fittings place the gasket against the flange side, but you should follow the instructions supplied with your specific fitting rather than assuming a universal arrangement.
Can I attach PVC to the existing rain barrel spigot?
Yes, if you have the correct adapter. First identify the spigot's thread type and size. Garden-hose threads and standard pipe threads are different, so a PVC fitting may not screw directly onto the outlet.
Do I need PVC cement?
Use PVC primer and cement only on compatible PVC solvent-weld connections. PVC cement does not replace the bulkhead gasket and should not be relied on to seal PVC directly to the barrel wall.
Why is my bulkhead fitting leaking?
Common causes include the wrong hole size, debris under the gasket, an uneven barrel surface, a misplaced gasket, overtightening, or PVC pipe pulling sideways on the fitting. Drain the barrel before adjusting a leaking bulkhead.
Can PVC pipe support itself from the barrel fitting?
A very short connection may place little load on the barrel, but longer PVC runs should normally have separate support. Unsupported pipe can put leverage on the bulkhead and eventually contribute to leaks or barrel damage.
Can I use the same PVC connection for an overflow?
Yes, but the overflow must be sized for the incoming water flow. A small pipe or restrictive fitting can become a bottleneck during heavy rain, even when the storage barrel itself is large.
