Hi, i am going to install a dishwasher and there is no connection (cold water feed) coming from the the mains (underneath the kitchen sink) After i've taken the connection from the mains, at the dishwasher end, should i install a stop cock or an isolating valve on the 15mm pipe before the connection goes into the dishwasher???? Any other tips as well i need to keep in mind for the dishwasher connection. Please Help!!!!