Outside tap from the back to the front

Yes you can usually tee off the existing outside tap supply provided it’s fed from the mains cold water and the pipework is adequately sized. For the new run 15mm barrier pipe is perfectly suitable if it’s installed correctly and protected from UV exposure (or use UV-resistant pipe/clipping where applicable). However personally I would use copper as is more robust and looks neater if the pipework is exposed but it’s generally more expensive and takes longer to install. Whichever material you useI’d recommend: - Installing an isolation valve on the new branch. - Fitting a double check valve if one isn’t already present. - Ensuring the external pipework is insulated where there’s a risk of freezing. - Clipping the pipe securely along the run. If the rear tap already has good flow and pressure, teeing off it shouldn’t cause any issues for normal domestic use.

yes teeing off the tap supply is okay and copper is more preferred to use. also a double check valve is required to fit before the garden tap accoding to regs