Fitting an overflow to the water butt using a tank connector

Our house’s previous owners installed a water butt. Like many of the decisions they made about the house and garden, this one sounds nice in theory but has a number of practical flaws.

Here’s the water butt, on the drive:


Ignore for a second the fact that it takes up substantial width of drive—we don’t have a car—and is mounted on a slope—we’ve managed to mitigate that through shifting and shimmying it around. With all that aside, it is:

  1. fed by a drainpipe that isn’t very well fixed to the wall, and tends to fall into its component parts during particularly bad weather.
  2. has no overflow, meaning that when the water butt is full, excess water simply empties out, splashes by the brickwork, and flows down the drive into the street.

We’ve already managed to mitigate the problems with the inflow, by adding an extra bend to the drainpipe, and propping it up on a half-brick. Once we’ve got a permanent site, it’s now close enough to the wall that we can drill up a mount.

The outflow problem is a bit trickier. Really, it needs what YouTube instructional videos (American) call something like a bulkhead fitting. It took me a lot of googling, and visiting DIY shops (Plumb Center even denied they were sold in the UK), to realise that we usually call the same fitting a tank connector (how they plumb up is also slightly different, I think, but whatever works!) But the great thing about tank connectors is that (once you know what to call them) you find they’re sold in plenty of places: I got mine online.

The following, disassembled, was advertised as a half-inch, Hozelock-compatible connector. However, the measurement seems to refer to its inner dimension, and calipers put its outer width at something like 22mm. Luckily I already had a drill bit to match. Here’s the exploded view of all components and the bit:


From left to right: Hozelock connector; external nut; internal fitting with rubber gasket; drill bit.

Before drilling, I emptied the water butt a little, but not much. Just enough to be clear of the hole, plus a few more centimetres (but then I’ve got a history of drilling into containers holding water, so you might want to drain a lot more!) I did however need to take off the dust lid, and re-prop up the drainpipe on a different-sized brick:


Drilling was pretty straightforward: plastic is quite soft and fairly forgiving. One point is that it’s definitely worth fishing out the curls and disc of plastic that result, any of which might one day clog up the tap or the overflow pipe:


As the butt was mostly full, these all floated on the surface and were easy to spot.

I then re-filled the water butt with a couple of buckets of water, and was able to test its watertightness:


It pours! And there’s no moisture underneath the fitting (what you see in the picture above is just a few dints and scratches, not drips.) You can see there’s no gasket—the rubber “washer”—in this picture, as it’s on the inside of the tank.

Until I could return to the DIY shop for the remaining fitments, I added a temporary drain underneath; just a concrete channel, really:


Already it was an improvement, but yesterday I was finally able to connect a couple of metres of hose up. Here’s the finished system:


Two full watering cans, with a covering to prevent the cat from drinking diluted comfrey from them sometimes; a full bucket, which I added during a brief rainstorm before the heatwave began; and our water butt with overflow and a platform underneath the tap so the cans line up properly with it.

In the interim, the barrel has dropped to perhaps only a third full, so right now the full system isn’t tested. It didn’t feel right, wasting drinking water in the volumes needed to test. But sooner or later there’s bound to be a spot of rain in Sheffield, right?



  1. Julieanne · July 26, 2016

    Well done on sorting this out. You are so clever J-P


    • jpstacey · July 26, 2016

      Oh, I’m not really! I think finding the Hozelock connector was key: until that point, I was hunting for a connector of the right size, piping of the right size, a drill bit of the right size etc…. In the end the Hozelock needed a different-sized hole than I expected, but I just luckily had another drill bit to match!

      I’m not normally one for proprietary fittings, but Hozelock is so ubiquitous (and all the DIY chains have knockoffs) that once you get that, the rest turns into an exercise in Lego building!


  2. Pingback: Chainsawing logs and fixing up the new store and old water butt | The next square metre

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