Your cold water storage tank, and any header tank in the attic, usually needs to be dealt with as part of the conversion. There are three common outcomes: the tank is moved to a new position, boxed neatly into the new layout, or the system is changed altogether, for example to a pressurised or mains-fed system that does without a storage tank. This is completely normal and it is planned for at the design stage, not left as a surprise on site.
Which option suits your home depends on the existing plumbing and the room you want. Moving or boxing a tank keeps the current system largely as it is, and can be the simpler route. Switching to a pressurised or mains system frees up the space entirely and can improve water pressure, though it is a bigger change to the plumbing and needs to be costed properly. We look at all of this when we assess the attic, so the decision is made deliberately.
The important point is that the tank is never simply worked around or ignored. It is factored into the layout from the outset, which is part of why we do a proper design and structural stage rather than starting to build blind. The plumbing work forms part of the first fix during the build, alongside the electrics.
If you are wondering how your particular setup will be handled, or whether your attic suits a tank move or a system change, our suitability guide is a good starting point, and the full process is set out step by step. To get specific answers for your home, book a free assessment.