plumbing into a detached garage

[BoxBasher]

Thanks for your reply BoxBasher. Where I tee off the tap and water to the garage, would I need to use a non return valve or isolator

Isolator yes, for common sense sake. Use a full bore isolator or BS1010 Stoptap so as not to restrict the flow.

As for non return (double check valve) it will depend on what else you are having fed from the pipe as to whether it is necessary. eg a hose union tap. If it's just the washing machine then backflow prevention isn't neccessary but a single check valve will prevent any water getting pushed back from the flex in the hose (may lead to a TCP taste in your water).

If you are going to the trouble of lots of plumbing work then throw a double check valve in anyway, this will "future proof" the installation if you wish to install a garden tap further down the line.

 

[superted]

Thanks for that.
So just to confirm:
when I cut the pipe off where the orginal water tap is (off the kitcen wall) I need to fit the isolator and then connect the tee to the other end of the isolator. On one side of the tee put a new outside tap. On the other add a no return value and then connect that pipe to the blue pipe which will then connect to my washing machine in the garage.

 

[BoxBasher]

Put the Double check valve after the isolator, before the tee. This will provide bacflow protection for both legs (garden tap requries one anyway)