Legionella risk of expansion pipe to water tank

[MOSSEP]

Hi, been asked to do a job which seems a little strange.

Large office building in London, expansion pipe to roof mounted cold water taken has broken off leaving a hole in the tank, this was noticed when the annual legionella risk carried was out and they have said that the hole needs to be filled up. I said thats easy enough, I will fix the pipe and put it back into the top of the tank so its back as it was. They said no, its a legionella risk having it back in there and they should have another tank fitted for the pipe to go into that then discharges into a gutter, and they will fill the hole. The client is worried about the legionella risk so just wants to do what they have requested, so, is there a risk involved if I just repipe it as it originally was?

Martin

 

[MOSSEP]

 

[Last Plumber]

Sorry, might be me but are you talking about the feed and expansion pipe in the bottom of the tank or the vent pipe through the lid ?

 

[Last Plumber]

Oh right seen it !

 

[Last Plumber]

It's the vent pipe isn't it ?
It's supposed to vent over the tank !

 

[MOSSEP]

You got it, the vent pipe that used to go into the lid. Thats why Im a bit puzzled as so why they say it will cause problems?

Assuming it doesn't go back in, other that a waste of water when it vents, is there any reason why it cant go into the gutter?

 

[1Steven]

Legionella says otherwise, do as your client ask get them to sign that that's how they want it. This will rumble on until the cows come home. In theory L8 is right, but thats not how we do it. Makes no sense but I do see your dilemma. Best of luck.

 

[MOSSEP]

I did say to the client that they should get the request in writing form the company that carried out the test.

Is there even any point to discharging it into a separate tank? It may as well go straight into the gutter if thats where the tank will empty when it fills.

 

[Best]

Sorry stating the obvious, but - How do they figure out the vent pipe is risk of Legionella?
I guess they theory is the pipe is open to the atmosphere and the water inside it is heated to some extent. Storage tank water is exactly the same anyhow.
I would be careful about putting the vent to elsewhere where it could freeze or the hot water damage something. The end of vent pipe would need to be not too low or it would start a syphon and empty the cold tank.

 

[Chalked]

Legonella risk assessments!! You can go on a course now for a few hundred quid and call yourself an expert. ( one day course!) the troubleis, they know nothing about plumbing installations.
The very small risk is outweighed by the risk of siphoning dirty stagnant water from the seperate cystern.
Apparently, one of the greatest risks for legionella, is the end of the spout on a hot tap!

All you can do is what they say I'm afraid.