Sink Mixer taps when using with a Header tank in loft

I used to hear years ago that the UK and Ireland used to have 'seperate' hot and cold taps at the sink for a valid good reason , that it was by law (water laws) so that the water mains (cold) was seperate from the (hot water system) coming from the storage tank up in the loft. citing that the storage tank can harbour stale water and flies and other insects and that if there was a mixer tap there is a possibility that the water from the storage header tank / copper cylinder could syphon into the cold water mains and infect others in the neighborhood give them that legionnaires disease or whatever its called .

- i thought I read somewhere it was only OK to have a mixer tap on systems that have combi-boilers because they dont have header storage tanks built into the system? - but our house we are in was built in 2008 and has a mixer tap in the kitchen sink and has a header storage tank in the loft.

 

Some "mixer" taps have two separate water ways through the spout to the end of the spout. Hence the water does not mix until it has left the spout.

 

As Bernard has mentioned,there are suitable mixer taps available,not many thou.

Bristan do a range called 'club' dual flow their budget brand,they look very basic but a great problem solver.

The hot and cold water only comes together when it exits the spout.