Can overflow pipes be joined for Water Tank & Expansion

[pete11]

I am in the process of re-routing overflow pipes for the Water Tank and Expansion Tank in the loft, reason being the overflow pipes currently exit the house through the fascia front and back and fascia is being replaced with UPVC, so don't want pipes sticking out!
I am going to route the overflow pipes to the side of the house through the brickwork where the pipes will not be so visible.

Is it ok for me to join the overflow pipes in the loft with a T join and have only 1 pipe exit the building?

 

[wingcoax]

Don't see why not. As long as there is no danger of cross feed.

 

[kirkgas]

cold water storage and F&E tanks should have seperate overflows, also you need to watch the size of pipe, the water regs say overflow pipe needs to be a minimum size in relation to size of ballvalve (i think it is X2) so if you have 2 ballvalves overflowing full bore at the same time the water may not exit quickly enough and spill back, also if the outlet gets blocked you might get cross contamination. something else to consider is that overflow pipes should be placed where the water will be visible whilst not causing a danger

 

[Nige F]

That`s ok M8 - SDS a hole straight through from inside and make sure it`s rising so the water runs back down the outside wall leaving a big stain that tapers from the gash of a hole - That`s 21st Century plumbing

 

[Boilerman2]

I saw an overflow with such a big rise that the water poured over the top of the tank before it reached the discharge point outside