Yep, I agree with coolvt. Buy a jug of CLR at the hardware store. Shut the water down and remove the ceramic cartridge from the tub/shower valve. Soak the cartridge in the CLR for about an hour, rinse off and reinstall after inspecting the interior of the valve for any calcium/lime buld-up. As for the leak.....forget about it. You don't have one. If you did have a leak, either you or your neighbours would know it. And it's not a water pressure problem, it's a water volume problem. Something is restricting the flow of water to the tub. Take your shower head off and soak it in the CLR too. Showerheads are notorious for lime/calcium deposits clogging them up.

This is an old thread but it helped me. We had a leak under the kitchen sink, somewhere. There's a leak it turns out on the hose for the sprayer. 'kind of where it forms a 'U' near the weight. We have a Kohler K560 CP. (one handle for hot and cold) For some stupid reason I shut off the hot and cold valves under the sink. But it was nice that after 3 years they were not frozen at all. So im using a bucket under the leaky line until I get the replacement hose. ANYWAY, when I turned on the valves and the faucet, hot did not work at all, and cold worked normal. And then I lost some pressure on the cold. So I eventually tried what was recommended in this thread. I shut off the hot valve under the sink and I detached the hot line at the valve point and put it in a bucket. The cold valve was open, and I opened the cold full blast at the sink and held my hand tight over the faucet tip. I did that a few seconds. I was glad to see water and sediment had shot out of the hot line into the bucket. I reattached the hot to the valve and opened the valve. Both hot and cold water flow were restored. So I haven't flushed out the cold line because I dont want to break what isnt broken. :)

The reason authorities advise boiling water when the water pressure is low is to eliminate bacteria which could have contaminated the water and may make people sick. It won't hurt plants, but if unboiled water gets on your hands don't touch your mouth or eyes.

Pulling a pump can have its problems. If the down piping is metal or solid plastic, the assembly is lifted and then held by clamps such as these as the pipes are unscrewed or cut: https://americawestdrillingsupply.com/wellpipeclamps.html Wooden clamp blocks, etc. can also be used. Many hands will help getting the job done. With my solid plastic pipes, I got away without having clamps, but at 15-20 feet of height, the piping would break and come crashing down on us (old solid plastic gets brittle). Luckily no injuries, and only 100' of pipe to pull (!!!), but I didn't know better at the time. If the piping is flexible poly pipe, the assembly can be lifted and withdrawn sideways into the yard. I installed a new 3-wire pump. The benefit of 3-wire pumps is that the start capacitor for the motor is above ground, so if the capacitor fails, it is easily changeable. Two-wire pumps have the start capacitor inside the pump assembly. My pump went back in with 100' of flexible poly pipe, brass hose barb adapters and double stainless clamps on each end. Its also a good idea to tie a polyethylene rope to the pump and tie it off at the top of the well; if the piping ever breaks you won't have to pay a well driller to retrieve the pump for you. If anything needs lubricated (pitless adapter, hose barbs, etc.), Crisco is used. Yep, Crisco, right off the grocery store shelves. Around here (Indiana), it's typically a $500 charge just to open a well. Then parts + more labor $$ to fix things. Either way you go, I just wanted you to be informed. Good luck!