Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. This article contains affiliate links.
Installing a water butt on a shed usually means connecting a butt to the shed’s existing gutter downpipe so rainwater from the shed roof is collected for garden use. This guide covers the key steps using a downpipe diverter, based on manufacturer instructions for a typical water butt kit and a diverter filter. It assumes your shed already has guttering and a downpipe; if not, you will need to fit those first.
Table of Contents
Check your shed’s downpipe and site
Before buying any kit, measure the outside diameter of your shed’s downpipe and check the material. Shed guttering can use smaller downpipes than house guttering, so a domestic diverter may need an adaptor or may not fit at all. Compare both ends of the diverter with your exact pipe and bracket arrangement. Ask the supplier to confirm any adaptor combination, and check the permitted pipe materials before ordering.
The ground where the butt will stand must be level and firm. Do not place it on uneven or loose ground. The butt needs to be close enough to the downpipe for the flexible connector hose to reach; some kits include only 500mm of hose, so check the hose length before positioning.
Compatibility is product-specific. The Gutter Mate and a basic kit supplied with a water butt can require different adaptors and different cuts. Check the current installation sheet for the exact diverter you are buying; do not select a reducer from the pipe diameter alone.
Position and prepare the water butt
Remove the lid from the butt. Fit the tap using the back nut and rubber washer supplied, tightening securely but not overtightening. Fit the hose connector to the butt, again using the rubber washer and hex nut. Place the butt on its stand in the chosen position, with the lid off. Use a spirit level to check that the rim is level both front-to-back and side-to-side. If your spirit level is shorter than the butt’s diameter, place a straight length of wood across the rim and level on top of that.
Mark and cut the downpipe
First put the empty butt and its approved stand in their final position. The stand changes the tank height, so measuring before it is fitted can put the diverter at the wrong level. Use a spirit level to transfer the manufacturer’s specified reference point to the downpipe.
Read the complete installation diagram before marking any cut. Some products reference the tank rim, others the maximum water level or a mark on the fitting. Use only the offsets and cut-out dimensions shown for your exact kit. The Garden Lake 200L kit and the Gutter Mate filter use different procedures, so their measurements must not be mixed.
Check that the downpipe is supported as required before removing a section. Recheck the marks against the installed tank and stand, then move the empty butt clear of the work. Use a tool suitable for the pipe material and follow its safety instructions. If the pipe is shared, fragile or difficult to support, obtain appropriate help rather than cutting it speculatively.
Fit the diverter and connect the hose
Fit the diverter and restore the pipe supports according to its instructions. Connect the hose to the nominated tank inlet with the supplied seals and fittings. Keep the hose within the permitted length and route, with no stretched joints or kinks. Before adding water, confirm the relationship between the diverter’s reference level, the tank inlet and its maximum fill level.
Where a diverter returns excess water to the original downpipe, that overflow behaviour depends on correct installation. Do not assume that a hose placed at an arbitrary height will prevent overflow. If the system has a separate overflow outlet, fit the intended route and keep it clear.
Using a diverter with a built-in filter
If you want to reduce leaves and debris entering the butt, a diverter filter such as the Gutter Mate needs to be fitted using its own installation procedure. It has a removable filter basket that is designed to be removed for cleaning, and it automatically redirects water down the downpipe when the butt is full. The Gutter Mate is supplied with a square-to-round adaptor for square downpipes fitted with close-fitting brackets; if your square downpipe uses standoff brackets, you may not need the adaptor. For smaller shed downpipes, confirm the required adaptor arrangement with the supplier. A fine mesh insert is available if you want finer filtration, but it is not essential for general garden watering.
The Gutter Mate product information excludes downpipes larger than 100mm diameter; other diverters have their own limits. Always follow the manufacturer’s instructions for your specific diverter, because the cut-out height and hose connection details can vary between models.
Final checks and winter care
After installation, check that all connections are tight and that the butt is stable on its stand. Do not use electric power tools in the rain or if there is water in the butt. Follow the tank and diverter manufacturer’s instructions for freezing conditions; some require draining or disconnecting components before frost. If you have used a diverter with a filter, clean the filter basket periodically to maintain flow.
During the first rain, inspect the system from a safe position. Check joints, the stand and the overflow arrangement, then recheck after the tank has filled. If the base settles, drain the tank before correcting the support. Do not try to lift or reposition a full water butt.
Useful products for this job
The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.
- Water butt with stand and diverter kit: Provides the butt, stand, tap and diverter needed for a shed downpipe installation; the kit instructions give the exact cut-out measurements. Check the downpipe diameter and material; ensure the kit includes a hose long enough to reach from the butt to the downpipe; confirm the stand is suitable for your ground. Search Amazon for Water butt with stand and diverter kit.
- Gutter Mate Diverter & Filter: A diverter with a built-in filter that fits common downpipe sizes and automatically redirects water when the butt is full; useful for sheds with leaf debris. Check your exact downpipe shape, diameter and bracket arrangement against the current Gutter Mate instructions; confirm any required adaptors with the supplier. Search Amazon for Gutter Mate Diverter & Filter.
- Manufacturer-specified downpipe adaptor: May be needed when the shed downpipe and chosen diverter use different connection sizes. Confirm both mating diameters, male/female ends, material and the diverter manufacturer’s approved adaptor arrangement before ordering. Search Amazon for Manufacturer-specified downpipe adaptor.
Related garden guides
- Best Garden Water Butts with Tap UK (2026): Save Water & Money
- How to Choose the Best Garden Hose in 2026: A Complete UK Guide
- More garden irrigation guides
Sources and further guidance
Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.