Drain Valve

[jaffveyda]

Ca any tell me please how and where install a drain valve for my wc system?
Any pics appreciated.

 

[jaffveyda]

I bought something like this http://www.watercoolinguk.co.uk/p/14"-BSPP-Ball-Valve_88.html
ALong with that i have 90 degree angle which i think i will fit on the site of the reservoirs.i ont know if that would work.