Sorry for the convoluted post...
A couple of weeks ago, I posted a query about fitting a thermostatic shower in place of an electric power shower as part of a bathroom refit. At the time, a couple of people advised that the cold water header tank in the loft was unnecessary with a combi boiler, and I should bypass it and run the mains cold water feed directly into the bathroom.
Started the job today, with existing suite duly gutted out and the pipes capped off with isolation valves. I've spent a couple of hours identifying the mess of pipes in the loft, and managed to identify the mains cold water feed, which actually runs up through the bathroom via a 15mm copper pipe. It then enters the loft, links into a tangled mess of redundant pipes and goes into the header tank. from there, it comes back down to the bathroom via a 22mm pipe to the bath tap, and then reduces to 15 mm for the supply to the sink and toilet.
The mains feed in the bathroom, and the toilet feed (which is the end of the line as it were) are about 18 inches apart, so I'm wondering if it's okay to connect the mains to the toilet end of the pipe - 15mm to 15 mm, and have the supply terminate at the bath on the 22mm pipe. That would make all the pipe work in the loft redundant and I could then remove the whole lot and the header tank.
Is it okay to do this?

