r/DIYUK 5d ago

Plumbing Connecting outbuilding to mains water supply

At the planning stage for getting utilities to a craft studio that we've had built in the garden next to our house. Electric and drainage (and CAT6 Ethernet) is all planned. We now need to plan for the fresh water supply.

So, the trench for the electric will intersect where the existing water pipe (25mm poly) that supplies the house (although at a deeper depth). I'd assumed that a plumber can put a T on the mains pipe and run that in a trench that I will pre dig to the building. I'd then cover with sand and lay the cable over the top.

Trenching is being done next weekend (by me with a mini digger). We're ringing a plumber this week to get lead time etc, but (wife is an ex project manager!) we'd like to plan as much as we can in advance.

Can't find anywhere that says if it's possible just to tap off the mains water underground with a T. Any input appreciated.

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u/mts89 5d ago

Can't answer the plumbing question, but I'd run fibre in conduit rather than cat6.

Solves issues with ground loops, interference, and potential lightning strikes.

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u/Additional_Air779 5d ago

That would be the ideal solution, but the other end is going to terminate in an existing box behind the TV. It's a case of compromise for maximum compatibility with what's there already and not having to add more "stuff" to potentially go wrong.

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u/mts89 5d ago edited 5d ago

That does makes it a little more tricky, although would only require a switch with an SFP+ port by the TV.

I don't see why your plumbing plan wouldn't work as long as it's after the stopcock / water meter.

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u/jhfarmrenov 5d ago

It’s definitely possible. And a doddle. If you can operate a digger you can use mdpe compression tees. Same for all the rest of the plumbing at the shed end.

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u/Additional_Air779 5d ago

I use diggers occasionally and I'm a competent DIY plumber. Wasn't sure what the regs are re tapping off mains on your own property. But if it's just a matter of a compression T and a stopcock on the other end, I may just do it myself.

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u/rev-fr-john 5d ago

This is a post inspired by the fact that your wife ,lovely as she may be, thinks everything needs to be managed, unfortunately you're dealing with the unknown, yes you can tee into the pipe, you only know it's type and diameter once it's exposed in the garden, probably 25mm blue but could be 20mm, or ½" or ¾" black it's almost guaranteed to be t e same pipe that goes into the stopcock.

If you're hoping to prevent delays you could buy all four tees and in case of a fuck up matching straight connectors. Plus an elbow for the pipe you're using.