Outdoor plumbing

[Martin Pentreath]

While my patio is being relaid I'd like to put some pipe under it to supply a tap on a garden wall. The pipe needs to leave the kitchen at a level above the DPC, run a short distance down the outside of the kitchen wall, go underground beneath the patio and then re-emerge at the base of the garden wall and run up the wall to the tap. For the visible parts of the pipe I'd like to use copper, but it would be easier to use plastic piping underground, so after some google research on this group I've decided that I'll use MDPE pipe for the underground stretch. Rather than using the rubbery copper adaptors from Screwfix to fix the plastic pipe to the metal (

) I'd prefer to use an MDPE adaptor ( ) and screw a brass compression fitting onto it. Does this all sound OK? Will the short lengths of copper be alright out in the elements?

Also what should I do about frost protection? The tap would only be in use during the growing season, so I'd be turning it off from a stopcock inside the house during the winter. The piping would be a 'U' shape so water would lie within it, and I can't see any easy way of providing an accessible way of draining it from a lowpoint. Is it enough just to leave the outside tap open to allow room for freezing water within the pipework to expand?

[BigWallop]

Copper pipe full of water doesn't really take kindly to being below freezing point, so the copper definitely needs to be lagged or, at least, "fully" drained off in the cold spells. It is easier to run a small diameter plastic pipe for the whole installation and, you should still lag the exposed sections and keep the subterranean section to at least 600mm (2 ft) below the surface of the soil to prevent it from freezing or being hit by a shovel when digging.

A stop valve and drain c*ck, at the lowest possible point, should also be installed so that any leaks or unauthorised operation can be controlled from inside the house.

[Toby]

If you look on

or you can get a wallplate directly suitable for the MDPE pipe. As BW also suggested, lagging is a good idea so copper would get hidden by it anyway. The lagging seems to take masonary paint OK to help it blend into the wall if that's important.

[Lurch]

On 5 May 2004 15:20:50 -0700, in uk.d-i-y martin [e-mail] (Martin Pentreath) strung together this:

What about putting a tee in at the low point below the tap then fit a blank to it, you could then turn off the supply in the house then unscrew the blank and the water falls out of the pipe.

[Pete C]

Hi,

You might be to use 22mm copper tube for show and run some reinforced hose inside that, with some space available for expansion when the hose gets frozen.

Water expands 1/11th when frozen, but the diameter of the hose would only increase about 5%.

cheers, Pete.