Fit a water butt with a downpipe diverter

Fit a diverter and water butt to your downpipe, on a stable base, so rainwater collects without overflowing your gutters.

WB-01Gather your tools and check the kitLay out the diverter kit and water butt and check the contents against the instructions — kits vary between manufacturers. Check the diverter matches your downpipe shape and size (usually 65mm or 68mm round, or 65mm square uPVC). You'll need a hacksaw, tape measure, marker pen, spirit level and a bucket.

1 each · Water butt (200L) with tap

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1 each · Downpipe diverter kit

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1 each · Hacksaw

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1 each · Spirit level

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1 each · Tape measure

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1 each · Marker pen

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WB-02Choose a level, stable spotPick a position within about 1m of a downpipe, on ground that can take the weight of a full butt — up to 200kg for a 200L butt. Avoid soft lawn edges or loose gravel. Leave enough room in front of the tap to fit a watering can underneath.

WB-03Build a firm, level baseLay 2-4 paving slabs on a bed of compacted hardcore or sharp sand, and check the surface is level in both directions with a spirit level. A full butt is heavy and will tip or sink into soft ground over time. A purpose-made plastic water butt stand works just as well if you'd rather not lay slabs.

4 each · Paving slabs (450x450mm)

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1 each · Sharp sand (25kg bag)

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WB-04Position the butt and mark the cutting lineStand the butt on its base next to the downpipe and offer the diverter up to check the height. Mark the cutting line on the downpipe at the height given in your kit's instructions — this is usually measured down from the gutter outlet, not up from the ground. Keep the mark square across the pipe using the spirit level as a guide.

WB-05Cut into the downpipeBefore you cut, check the pipe for any cables clipped to it — satellite, alarm and outside light cables are often run along downpipes. Unclip and move these out of the way first. Support the pipe as you cut so it doesn't crack, and hold a bucket underneath to catch any rainwater already sitting inside. Cut along your marked line with the hacksaw and remove the cut section cleanly.

1 each · Bucket

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WB-06Fit the diverter unitPush or clip the diverter body into the two cut ends of the pipe, following your kit's instructions — some use rubber seals, others a screw clip. Make sure the outlet spout faces towards the butt, and check any directional arrow on the unit points down towards the drain, so overflow still runs away once the butt is full.

WB-07Connect the hose to the buttPush the supplied hose onto the diverter spout, then into the inlet hole on top of the butt, trimming it with the hacksaw so it doesn't kink or sag. Fit the small leaf strainer if one is supplied, to stop debris washing into the butt.

WB-08Fit the tap and check the overflowIf the tap isn't already fitted, push it through the pre-cut hole near the base of the butt and tighten the backnut by hand — don't overtighten, as this can crack the plastic. Check the overflow outlet near the top of the butt is connected so excess water drains back into the downpipe once the butt is full, rather than spilling over the top.

1 each · Water butt tap kit (if not pre-fitted)

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WB-09Secure a tall or unstable butt to the wallA full butt is top-heavy, so if yours is tall or the ground isn't perfectly firm, strap it to the house wall once it's full. This step is for solid brick or block exterior walls only — outside walls are almost never plasterboard or stud, so that guidance doesn't apply here. Before drilling, use a cable and pipe detector, but still assume there could be a cable or pipe there anyway — detectors miss deep cables and anything in conduit. Find your stopcock (usually under the kitchen sink) and check it turns freely before you start, and isolate the circuit at the consumer unit if you have any doubt. Drill a 6mm hole, insert a 6mm x 30mm wall plug, and fix a galvanised pipe strap or ratchet strap over the butt with a 50mm screw.

1 each · Galvanised pipe strap or ratchet strap

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2 each · Wall plugs (6mm)

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2 each · Screws (50mm)

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WB-10Fill and test the systemRun a hose over the roof or wait for rain, and watch the diverter to check it's channelling water into the butt rather than straight down the pipe. Check the tap and overflow both work, and look at every joint for leaks. Reseat or tighten any fitting that seeps.

WB-11Tidy upBin the offcut of downpipe — uPVC pipe usually isn't accepted for kerbside recycling, so check your council's rules. Sweep up any debris around the base, wipe down the diverter and joints, and store your tools away. Check everything again after the next proper downpour.

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