We have a large oak barrel which we use as a WaterButt had it for a couple of years now. To be honest it as Always had a slight leak/drip which as been a pain. But since the last dry period which lasted a couple of weeks the water within was used on various plants around the house.
Then when it started raining again over the recent weekend the water runs out of the gap between several panels quicker than the butt can fill from the guttering !! I was out there in the pouring rain trying to re seat the panels without any success & it is possible to see day light between a number of panels.It is not possible to follow item seen on websites that say fill and roll barrel because the top been removed to turn into a Butt
The problem with wooden barrels is that when they're empty the wood shrinks - hopefully the wood should swell now that it's wet and the joints should soon tighten up again.
Not desperately practical in a climate like ours when we can't keep the barrel permanently full
Have you tried hammering the hoops down to tighten the joints. I find this works with properly coopered half barrels when I want them to hold water. using a hammer and piece of wood or metal I work around the barrel driving the hoops tighter.
The rings all appear to be riveted in a uniform fashion all around the barrel. I think those are there for a purpose rather than just show I will have to inspect them better this evening.
Told we are due lots more rain this week/weekend so would like to sort this out. The PVA seems a good idea I did think of bathroom sealant but it says not to be used under water. The barrel cost a £100 plus so I thought it was going to be the Mutts Nutts & so much better than the blue plastic ones I could have brought for £30
Not considered that option which would be the easiest one perhaps. Will try the twating of the rings with an hammer next time it rains. That might help