Dead leg problem? Outside tap removal, but pipes are underground...

[Plumb Line]

Hi all

Got a very old looking outside tap at our house which is not in use. A plumber is visiting soon to do a bathroom refit, and whilst here will remove the tap and cap it off. I asked whether this would cause a problem with a "dead leg" and he said no, but I want to check with you guys here please.

The tap is behind a fake door which is just there for aesthetics as it's bricked up behind. I guess the tap itself is a dead leg isn't it? If so, shortening it can only be a good thing, but is it enough?

The last photo shows the water meter cover in the ground. So the tap isn't far away from that. There are two stop cocks in the house, neither of which are near the meter or outside tap. One is around 8 metres to the left and the other about 10 metres to the right (both in the middle of the house, not on the outside wall you're looking at). So I've no idea at all where or how the outside tap is connected, if/where it is tee'd off from, etc. Also, a you can see there is a slab of old concrete in front of the door. Plus the oil pipe is underground somewhere between the meter and tap, which would make digging a little more of a pain.

Goes without saying that the cheaper and easier option is preferable, but at the end of the day I want it to be right and most importantly I want my drinking water to be safe.

To dig or not to dig (cap and forget)... That is the question?

Many thanks for any help

 

[Deleted member 120897]

It all depends on where it’s being capped off (maxium from a fitting is twice the pipe size diameter) from, but I’d say it would be considered a dead leg.

 

[Chuck]

It all depends on where it’s being capped off (maxium from a fitting is twice the pipe size diameter) from, but I’d say it would be considered a dead leg.

Strictly speaking it's already a 'dead leg' if the tap is only used infrequently. If you replace the tap by a cap it becomes a 'blind end'. Anyway, pedantry aside, the easiest way to deal with this is to leave the tap in situ and regularly run off a couple of gallons through it to flush out the dead leg. Dead legs should not be more than 3m in this context. If the OP wants to remove the cap then he should trace the pipe back to the point where it branches off the supply.

If it were my house, I'd base my decision on whether there was any prospect of bringing the tap back into use in the future. If not, I'd bite the bullet and trace and disconnect the branch. My preference is to fix things properly once and then never need to worry about them again.

This topic is covered quite well here:

Management of dead legs and blind ends in water systems

Blind ends and dead legs increase the risk of biofilm forming and creates the right conditions for Legionella & other waterborne pathogens to proliferate.

resources.waterhygienecentre.com

 

[Basher]

To dig or not to dig (cap and forget)... That is the question?

You could hire a pipe detector for a day and try to establish where the pipe goes. That might help find where it joins the supply more quickly.
eg: Cable Avoiding Tool Cat3 - HSS Hire - https://www.hss.com/hire/p/cable-avoiding-tool-cat3

 

[Plumb Line]

Many thanks for the helpful replies. There's no plans to use the tap in the future as we have another two outside taps, both in far better locations, and newer. Plus we want to tidy up that bricked up doorway and do whatever a builder sees fit. I'm thinking the tap will be in the way when it comes to that.

Someone elsewhere has also pointed out that the pipe might be lead.

All in all I think dig and do it properly might well be the best solution....

@Basher - thanks for that idea. Had there not been a recent dig there to help me know where to start, I might well have gone for that. But hopefully by working off the photos carefully, and digging carefully, I'll be able to save the few quid the gizmo would cost.

Cheers