Legionaires risk do I need to drain system

[Gary111]

Hi, I've got a rental flat that's been empty 8 months, it's got an electric shower and electric water cylinder.
Do I need to drain the system to avoid legionaires disease risk?
If so how?
Thanks

 

[ianmcd]

No just take the temp in the cylinder up to 60 degrees C and it will be fine

 

[Gary111]

No just take the temp in the cylinder up to 60 degrees C and it will be fine

Thanks, does it not affect the cold side ?

 

[CBW]

Ideally maximum length of time cold water should be left without being used is 30 days, before it becomes stagnant/bacteria starts to grow. Not 100% sure on domestic premises though. Legionella bacteria is caused when the cold water (usually stored) is heated above 20 degrees Celsius, towards 50 degrees. 60 degrees will kill this bacteria, which is why hot water is stored at this temperature.

 

[JohnD]

You also presumably have a cold water tank in the loft. This is more likely to be dirty and stagnant. It might supply the cold bath tap. To check, turn off the main stopcock and open the bath tap. If it runs, it will probably drain out the tank in about 15 minutes. Give it a clean and rinse, refill and drain again.

If the tank does not have a loose-fitting plastic lid, it is particularly likely to be dirty. If it does not have a full insulating jacket, it is particularly likely to be stagnant.

So fit these accessories if they are missing.

 

[Gary111]

Thanks there's no cold water tank, just mains,

 

[ianmcd]

Do you have an unvented hot water cylinder , post a pic if you are not sure

 

[Harry Bloomfield]

Thanks, does it not affect the cold side ?

It can do.....

The advice is that dead legs of pipe work should be removed from both hot and cold supplies - basically an original pipe system where it has been modified and long sections of 'live' pipe have been left in, but blanked off at the end. No proper flow through the dead leg of pipe, so it contains stagnant water - a breeding ground for bacteria.

Normally just running each cold tap in turn for a few minutes, to flush any stagnant water out of every pipe is enough.

 

[Gary111]

Do you have an unvented hot water cylinder , post a pic if you are not sure

Hi, yes a small under sink one.

 

[ianmcd]

Hi, yes a small under sink one.

No you have an instantaneous water heater, not a cylinder, no need to worry just switch it on and run a sink full of water off

 

[Gary111]

Thanks for your help

 

[Madrab]

Same with all your other pipework. If any water is sitting in the supply pipework for extended periods of time then flush it clear for a minute or 2 through each outlet to flush clear any standing water.

 

[Diver Fred]

Run the hot tap furthest away from the water heater until you can no longer bear your hand under it (or with a thermometer, the the temp no longer rises - should be a minimum or 50 degrees C) + i minute. Then flush the cold tap furthest away from the stop tap for minimum of 3 minutes (better 5), then all the rest of the cold taps for a minute working back to the stop tap. Wear a vapour protecting mask whilst you all the flushing.