I need a water butt overflow that can cope with 12m^2 of shed roof when the butt is full. I think I'll need something like 32mm drainage pipe. Can you get a spigot for this size pipe that screws into the butt and seals with a washer ? I don't think solvent weld would work on the water butt plastic. Cheers, Simon.
Peter
I want to install a water butt soon, to capture water from the summerhouse. Must admit, I'd not considered overflow - more whether I'd ever get it full...but I guess it needs thinking about. Not having bought the butt yet, is the reason for the overflow because the downpipe going into it is effectively watertight? And thus any overflow will go back up to the guttering it is supposed to be draining? I must admit, I'd thought the entry point was not so watertight, so any excess would have run off the top of the butt?
JW
Yes, it would run over the top of the butt - but it would then potentially flood the surrounding ground. To avoid that, you need an overflow which takes the surplus into a drain - and which can handle the maximum flow rate likely to come down the inlet pipe.
If you already have a downpipe going into a drain, a very effective way of filling a butt is to use a diverter like the one shown here:
Err. . the one referenced is only for 21.5mm pipe - which is only any use for things like toilet cistern overflows.
You need something like this instead:
In my case the 40mm overflow feeds to another butt further down the garden, the top of which is below the bottom of the first butt (steep garden) at this point this lower butt simply overflows onto the garden some 30' from the house and actually well below the foundations!
...and in my experience a downpipe diverter cannot extract water fast enough, i.e. if the butt is empty and we have a short heavy downpour the butt will get very little water from the diverter as it typically has a
15/20 mm pipe, if the main down pipe goes direct into the butt you catch all the available water, the surplus then runs out the 40mm overflow...Peter
You are quite right! See Marley Polypropylene Tank Connector WUM43GX Grey (Dia) 40mm EAN: 5011141007877
and the WUM33GX is the 32mm fitting.
That's what happens when you search quickly! ...and cheaper than I remembered.
Peter
Water butt lids IME aren't watertight, so any excess water would overflow. I have come across these rainwater diverters which feed water butts being blocked - in which case the downpipe fills and overflows at the top.
Yes, the pipe size does limit the rate. However, I've been surprised at how quickly my butt *does* fill up from one - and that's only capturing the water from one half of a (double) garage roof.
Cheers guys. I'm going to have to come up with a cunning plan for my overflow then, as it will be at the bottom of the garden, and due to the ridiculous design of these houses, there is no drain around the back of the house. Like Peter, I shall probably just have to work out a way to get it to disperse over the garden.
There is no guttering on the summerhouse yet - and it really does need it - so I shall be going with the 'full fat' pipe into the butt.
JW
Oo-er...only just read that back. Wasn't meant to sound that way! :-D
Not seen that but I've seen ours not able to cope with the volume of water trying to get through it and being a round or square divertor with round down pipe have four foot high fountains of water coming out of the corners. It was seriously chucking it down though probably around 50mm/hr but for only a few minutes.
As for capturing every last drop at normal rain fall rates I expect a diverter will capture everything. Most rain rates in the UK are measured at 1 or 2mm hour, or 40l/hr over 20m^2 for 2mm/hr. Yer average 20mm divertor outlet pipe will carry that no problem.
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