Where to get the water supplies for an additional shower?

[Pipster]

I am planning to fit a thermostatic mixer shower to my main bathroom and need some basic advice to consider further.
The water system is gravity fed with a cold water tank and expansion tank in the loft. A copper hot water cylinder is in the airing cupboard.
The main bathroom is next door to the ensuite where a shower is currently fitted.
Can I tee off the existing hot and cold pipes that supply the shower in the ensuite and run new pipes to the new shower?
Or, do I need to run a new cold feed directly from the cold water tank and the hot feed from the hot water cylinder / vent pipe.

Any help much appreciated.

Thanks

[marrtin]

You really need a separate supply for each shower. The problem is that if both showers were used at once, one could rob the other of water.

You must always assume that both showers could be used at once, and must ensure an even flow of water to avoid the possibility of scolding.