Dead Legs

[Pocster]

I have lots of temporary internal pipework all hep2o

 

Removing some of it will be a PITA so I'd rather leave it in place so some plumber long after I'm dead finds it and says WTF!

 

One long run - goes to the temp kitchen. I can't easily get to the tee to cap it off ( once new kitchen is functional ) does it matter if there's a few 'dead legs' that are maybe 3 metres or so long?

 

Appreciate that a hot water tap may need a few more seconds maybe to flow hot.

 

No issue other than that?

[Conor]

It's a potential health issue. Old, dead water will sit in those legs for long periods of time, stuff will grow, and then when you have a low water pressure event / shutoff / partial drain down, that old water will enter the system and potentially be a risk. 

 

Any dead lengths should be isolated where they branch off from the supply within 5x pipe diameters.

[Pocster]

4 minutes ago, Conor said:

It's a potential health issue. Old, dead water will sit in those legs for long periods of time, stuff will grow, and then when you have a low water pressure event / shutoff / partial drain down, that old water will enter the system and potentially be a risk. 

 

Any dead lengths should be isolated where they branch off from the supply within 5x pipe diameters.

Oh ! . The water in them won’t circulate? I.e eventually come out ?

[Conor]

1 minute ago, Pocster said:

Oh ! . The water in them won’t circulate? I.e eventually come out ?

Not if there is nowhere for it to go at the end. Turbulence will clear water to about 5x pipe diameters on the branch, no more. It'll need to be isolated at this point or have a way to be regularly drained off at the end.

 

This is why fire hydrants have a built in "duckfoot" or U bend in them, so when there is an issue on the water main, the horrible, stinking water in the hydrant doesn't flow back in to the main. Also why the meter box at the front of your property will have a non return valve.

[Pocster]

28 minutes ago, Conor said:

Not if there is nowhere for it to go at the end. Turbulence will clear water to about 5x pipe diameters on the branch, no more. It'll need to be isolated at this point or have a way to be regularly drained off at the end.

 

This is why fire hydrants have a built in "duckfoot" or U bend in them, so when there is an issue on the water main, the horrible, stinking water in the hydrant doesn't flow back in to the main. Also why the meter box at the front of your property will have a non return valve.

Could leave it and slowly poison my family ? . Guess though I’d better cut it out properly 🙄