How to connect two water butts together

Illustration of a covered rainwater butt beside a brick shed

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Connecting two water butts together is a practical way to increase rainwater storage without adding a second downpipe. The RHS advises joining multiple water butts with connector kits or siphons, and this guide explains the two main methods, what to check before you drill, and how to fit a linking kit securely.

Table of Contents

Two ways to link water butts

There are two common approaches: a top connection, which acts as an overflow, and a bottom connection, which equalises the water level between the two butts. The choice affects how the butts fill and how you use them.

Connection position	How it works	Best for
Top (overflow link)	The first butt fills to the height of the link, then water passes into the second butt, provided the inlet and diverter levels allow it.	When you want to draw water mainly from the first butt and use the second as reserve storage.
Bottom (equalising link)	Water can move between the tanks and their free water surfaces tend towards the same elevation. Flow restriction can cause temporary differences during filling.	When you want to use both butts interchangeably or draw from either tap.

What you need

Two water butts, ideally the same height and with flat sides for drilling
A water butt linking kit containing a flexible hose, two threaded connectors, two rubber washers and two backing nuts
A drill with a hole saw or spade bit of the size specified in your kit’s instructions
A spanner or adjustable wrench to tighten the nuts
A spirit level and a firm, level stand or bricks for each butt

Check the kit instructions before buying or drilling. Some kits specify a 25mm hole and a maximum distance of 39cm between butts, but these are model-specific figures, not universal rules. Always use the hole size and spacing given for your particular kit.

Step-by-step connection

Position the butts. Place both butts on firm, level stands or bricks so their taps are at the front and the sides to be connected face each other. The RHS recommends stands so you can fit a watering can beneath the tap. Check the distance between the butts against your kit’s maximum spacing.
Check the level. Use a spirit level to confirm both butts are level. For a low link, matching base and rim heights simplifies the arrangement. If heights differ, water surfaces can still equalise, but the lower tank may overflow before the higher one fills; check the complete layout.
Mark the hole positions. Decide whether you want a top or bottom connection. Mark the centre of each hole on the inside or outside of the butt wall, following the kit’s recommended distance from the top or bottom edge. For the Garland kit, the instructions say to drill approximately 5cm from the top or bottom, but this may differ for other kits.
Drill the holes. Empty both butts completely before drilling. Never use an electric drill if a butt contains water, as this creates a serious electrical hazard. Wear eye protection and follow the drill manufacturer’s guidance on clothing and hand protection. Use a hole saw or spade bit of the correct diameter, and drill slowly to avoid cracking the plastic. If the wall flexes, support the inside with a piece of scrap wood.
Fit the connectors. Fit the connector, washer and backing nut in the order and orientation shown in the kit instructions, then attach the hose to the specified connection. Tighten only as directed to create a seal. Do not overtighten, as this can distort the washer or crack the butt.
Test for leaks. Test the system in its final position. Add water gradually until it reaches the connections being tested, and watch for seepage. A few litres will not test a high overflow link. If a joint leaks, drain below the fitting before checking washer placement and the manufacturer’s tightening instructions. Check the overflow route as well as the joints.

Top or bottom: which should you choose?

A top connection is simpler to retrofit because it does not require the butts to be perfectly level, and it retains water below the link in the first butt before the second starts to fill. However, the second butt will only receive water when the first is full, so if you regularly draw from the first butt, the second may stay empty for long periods.

A bottom connection allows the water surfaces in both butts to settle at the same elevation, which is useful if you want to use either tap or connect a hose to one butt while the other acts as a reserve. A low link needs careful planning of tank heights, the hose route and overflow levels. If one butt is on a higher stand, water will flow into the lower butt until the levels equalise, which may leave the higher butt nearly empty.

Some kits, such as the Strata water butt connector pipe, can be installed at the top as an overflow link or at the bottom to equalise levels. The Garland linking kit also allows either position, but its instructions note that a bottom connection makes both butts fill at the same rate, while a top connection fills the first butt before overflowing into the second.

Practical checks before you start

Wall thickness and material. Most linking kits are designed for standard plastic water butts, but very thin or flexible walls may not seal well. Check that the washers sit flat against the inside and outside surfaces.
Distance between butts. The flexible hose in a kit has a fixed length, often around 500mm. If your butts are further apart than the hose allows, you will need a longer linking kit or a different arrangement.
Hole size. The hole must match the connector diameter. A hole that is too large will leak even with a washer; too small and the connector will not fit. Use the drill bit specified in your kit’s instructions.
Existing taps and fittings. If either butt already has a tap or other fitting near the planned hole, reposition the connection to avoid weakening the wall or interfering with the tap.
Child safety. Water butts should have close-fitting, secure lids. Keep children away from the work area, keep the tanks empty while making modifications, and refit the secure lids promptly after the work. Follow the manufacturer’s lid requirements; do not rely on the size of the container to prevent access.

Common mistakes to avoid

Drilling while the butt contains water – always empty it first and never use an electric drill near water.
Overtightening the backing nuts, which can crack the plastic or squash the washer so it no longer seals.
Using a hole saw that is too large or too small for the connector.
Placing tanks on unstable ground or ignoring different rim heights and overflow levels.
Forgetting to check the hose length before positioning the butts, leaving a gap that the hose cannot bridge.

Alternative: siphons and connector kits

The RHS mentions siphons as an alternative to connector kits. A siphon link can transfer water between butts without drilling, but it must be primed and may need periodic re-priming if air enters the tube. Connector kits with drilled holes are generally more robust for permanent installations, but siphons can be useful if you cannot drill or want a temporary link. Check the siphon’s instructions for maximum lift and hose length.

After connecting

Once the butts are linked, keep the connecting hose clear of kinks and check the nuts and washers at the start of each season. The RHS advises cleaning water butts annually with warm water and a little washing-up liquid, and keeping gutters clear to reduce debris entering stored water. If you notice the second butt not filling, check whether the water has reached the link, whether the diverter stops filling below that level, and whether the hose is kinked or blocked.

Products to consider

Two examples documented by their manufacturers are the Garland and Strata linking kits. The Garland water butt linking kit (W1871) includes a 500mm connector hose, two 20mm connectors, washers and nuts, and its instructions specify a 25mm hole and a maximum 39cm gap between butts. The Strata water butt connector pipe (GN811) also includes a 500mm flexible hose, twin threaded nuts and rubber washers, and can be fitted at the top or bottom. Both are examples of the type of kit you need; always check the exact hole size, hose length and maximum spacing for the kit you buy, as these details vary between models.

Keep a working overflow route

Two tanks can both become full. Check how excess water returns through the diverter or leaves the approved overflow, and keep that route clear. In a top-linked arrangement, a diverter that stops filling below the link cannot supply the second tank as intended. Follow the fitting levels in the instructions rather than choosing the connection height in isolation.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Garland Water Butt Linking Kit (W1871): A complete linking kit with hose, connectors, washers and nuts, designed to join two water butts with a 25mm hole and up to 39cm spacing. Confirm your water butts are empty before drilling, the distance between butts is no more than 39cm, and you have a 25mm hole saw or spade bit. Search Amazon for Garland Water Butt Linking Kit (W1871).
Strata Water Butt Connector Pipe (GN811): A heavy-duty plastic link kit with a 500mm flexible hose, twin threaded nuts and rubber washers, suitable for top or bottom fitment. Check the hose length is sufficient for your butt spacing, and that the threaded connectors fit the wall thickness of your water butts. Search Amazon for Strata Water Butt Connector Pipe (GN811).

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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.