Comparison guides
Mains-pressure or gravity-fed: what your shower is actually running on
The deciding factors
Gravity systems give gentle flow unless there is real height between the tank and the shower head, which is why top-floor showers in tanked houses so often disappoint.
Mains-fed outlets hold pressure well but share a single incoming flow rate, so simultaneous draw-off elsewhere in the house is the limiting factor rather than the shower valve.
Mixer valves and shower heads are specified for one or the other; fitting a low-pressure head to a mains supply, or the reverse, is a common cause of a brand-new shower underperforming.
Worth checking on site
Gravity systems give gentle flow unless there is real height between the tank and the shower head, which is why top-floor showers in tanked houses so often disappoint.
Common questions
How do I tell which one I have?
A cold water tank in the loft feeding the bathroom usually means gravity; no tank and a pressurised feed straight from the main usually means mains-fed.
Will a pump fix a weak gravity shower?
Often yes, provided the tank can supply the pump's draw and there is somewhere suitable and accessible to mount it.
Working out what is realistic in your space?
Room dimensions, the position of the window and where the waste leaves the building decide most of it. Send those and we can be specific.