Is the stop valve fully open? is the inline filter clean? check these first. check aerators too.
Insufficient water pressure or incorrect pipe sizing
Kitchen drains are usually larger in diameter compared to bathroom drains. This is because kitchen drains need to accommodate larger debris and handle higher volumes of water flow.
If it's coming from the roof then the bathroom ceiling will have a water stain on it too. If you don't see this then it is coming from your bathroom.
turn up the water pressure
U can't check Ur pressure reg
A water faucet is the mechanical device fitted to the water supply pipes over bathroom and kitchen sinks. When turned on they supply water.
suilage is waste that is disolved of excreta,it consist of waste water from kitchen,bathroom,laundary etc.
An aerator is on the end of your kitchen or bathroom faucet spout that unscrews and holds the screen and/or water saver.
Most likely your bath and kitchen faucets have aerators. whereas your bathtub and outside faucet do not. In areas of hard water, minerals and sand build up in the aerators and need to be cleaned or replaced. Also the aerators could be water savers and will reduce flow as well. Hope this helps.
If the whole house is served with well water there is no problem doing this. If only this bathroom is to be supplied with well water then it needs it's own pressure tank.
Possibly if the kitchen does not have an electric over and electric cook-top and no eclectic water heater in the bathroom. If they are electric have an electrician evaluate what is being powered in the kitchen and the bathroom to determine if a 50 amp sub-panel is large enough. I would for sure at least go with a 60 amp sub-panel.
Water proofing a new bathroom or kitchen is a very important part of construction. Any water that leaks or slips through a gap can cause rot and attract insects.