Little used outlets flushing and what is a "dead legs" ??

Little used Outlets should be flushed & what is and how long is a "dead legs" ??

Most offices, Factories and buildings have a tap or outlet that is little used or redundant pipework

This picture is a cleaners sink in a small industrial unit. You don't need to be an expert to see this is a little used outlet.

Next door to this locked and un-used sink was the sites showers. So not a great combination

This length of un-used water pipe will become a breading ground for bacteria if it is not flushed regularly. You will some times see on your legionella risk assessment a term know as a "dead leg" See diagram below for an example. 

Stagnant water favours Legionella growth. To reduce the risk you should remove dead legs/dead ends in pipe-work, flush out infrequently used outlets (including showerheads and taps) at least weekly and clean and de-scale shower heads and hoses at least quarterly. 

Technical Term for a dead leg
The term "deadleg" is a length of hot or cold water pipe through which water will never flow as the outlet has been permanently blanked off. A totally disused (dead) branch pipe.

The only safe solution is to remove the branch and tee completely and replace it with a length of straight pipe.

How Long is a dead leg 

In reality, great difficulty and expense can be caused in actually achieving this but it is the best long term solution. If this is not possible. A rule of thumb that you can use is :- anything over 1 pipe diameter up to a 28mm can constitute a dead leg. This is in domestic water  pipework. 

An example. A 15mm copper pipe should have a  dead-leg no longer than 15mm. Which is the length of a end cap.