Water Butt Linking Kits: Hose Length, Fittings and Tank Connections
Adding a second water butt can give you more space for collected rainwater, but a linking kit needs to match the tanks and the route between them. A hose that reaches the gap is only one part of the choice: the tank fittings, sealing parts and access for tightening also matter.
Use this guide to make a short list of measurements before ordering, rather than choosing from a photograph or a nominal thread size alone.
1. Decide what the connection needs to do
Start by separating three jobs: collecting water from a downpipe, linking two containers and taking overflow away. These can use similar-looking hoses, but they are not automatically interchangeable kits. A downpipe diverter is a different component from a through-wall tank connector. Decide where water will enter, where it will leave and which existing fittings you intend to keep.
The GRAF water butt connection kit demonstration shows the principle of joining two barrels with a hose and tank fittings. It illustrates a particular manufacturer’s system; it does not establish the drilling dimensions or installation method for every kit sold here. Follow the instructions for your own tanks and connectors.
2. Measure the hose route, not just the gap
Measure between the actual connection points with the tanks in their intended positions. Allow for the route around lids, taps or other obstructions, and avoid a length that must be stretched tight to reach. Also check that the proposed route leaves room to reach the nuts and to remove the hose for maintenance.
A short connection may suit two nearby tanks, while a longer route needs a different hose length. Extra length should have a planned route rather than an unsupported loop. Do not move or support a filled tank to make an unsuitable hose fit; follow the tank maker’s positioning and support instructions.
3. Keep the different size measurements separate
Hose inner diameter, hose outer diameter, connector thread size and drilling-hole size describe different parts of the connection. Do not substitute one measurement for another. In particular, the outside diameter of a corrugated hose does not tell you the size of hole to make in a tank wall.
For example, the seven-piece connector kit with 50cm hose lists a 25mm hose inner diameter and a 33mm outer diameter. Record both when comparing it with existing fittings.
4. Check BSP labels against the connector details
If a listing uses BSP sizes, check the stated connector specification as well; do not treat the inch label as a direct measurement of the hose or the required tank opening.
Write down whether the connection is to an existing outlet or a new through-wall fitting. A matching hose does not establish that a connector will screw into an existing outlet. Ask for the exact fitting dimensions if the listing does not resolve the match.
5. Check the tank wall and access before buying
Look at the proposed fitting position from inside and outside the tank where accessible. Check whether there is an existing threaded outlet, a prepared connection point or a location that the tank manufacturer permits you to drill. A connector with a lock nut needs a suitable way to fit and tighten that nut; do not assume you can reach through every lid or inspection opening.
If the tank has ribs, a curved surface or a narrow opening, confirm compatibility before ordering. The connector and its seals need to suit the intended wall and opening. Avoid copying a hole size or washer arrangement from a different product, even when the photographs appear similar.
6. Compare the complete kit contents
Check the contents list rather than counting the main objects in the picture. The 50cm seven-piece kit lists one corrugated hose, two connectors, two pads and two nuts. Those details help distinguish a complete connector set from a listing for hose alone.
The linking kit with corrugated hose offers selectable BSP diameter and hose length. Its listed contents are the selected hose, two barbed tank connectors, gaskets and lock nuts. Select both attributes and check the resulting availability before adding it to your basket; the list of possible lengths does not mean every diameter-and-length combination is available. A hole saw is not something to assume is included.
7. Make a final compatibility checklist
Before ordering, note the tank model, connection position, existing outlet details, hose route length, hose diameter and required connector type. Check the selected variant’s contents and the access needed for installation. If any measurement is missing, ask for the relevant specification before drilling or trying to adapt the tank.
Browse water butt fittings to compare the current connectors and kits. Keep the product instructions with your installation notes, and recheck the tank and fitting manufacturer’s requirements if you later change the layout. For other practical buying guides, return to Guides & Advice.