Alistair Ewen
Hi the main thing with gravity fed showers is you need to have at least 900mm from your showerhead to the underside of the cold water storage tank or it wont work properly. The other way is to install a booster pump which will increase the pressure to your showers.just one more thing if you are thinking about DIY do not pipe the showers off the main supply you need a supply from cold tank and a supply of your hot water cylinder hope this helps. Regards Alistair Ewen A and M Bathrooms
