There are many reasons your water pressure may be low and the issue could be simple or major. But before you try to fix anything on your own, it's best to read up on what may be the issue, and get a set of professional eyes on the problem.
Water supplier issue
You may be experiencing low water pressure because your water supplier is experiencing issues. Before you start looking for the issue, ask around, if your neighbors are experiencing it too. It's probably a city wide issue.
Your pipes may be clogged
We don't think about clogged pipes being an issue for low water pressure. But a clog can happen on any pipe, but this clog could be anywhere underneath your house so it will be time to call a plumber. Because even a small clog can cause low water pressure. And with it being an intake pipe the last thing you want to do is pour abrasive chemicals down there and contaminate your drinking water.
A clog in the pipes can cause low water pressure because your water can't move through it as fast as it needs to for higher pressure. A clogged pipe isn't just inconvenient for water pressure. A clog can cause worse problems down the road, like a burst pipe. If you suspect you've got a clogged pipe, like maybe something was flushed that shouldn't have been or you can't find an issue somewhere else, it's time to call a professional.
Corroded pipes
Pipes in older houses have an expiration date because they do corrode after time. If a pipe has corroded in your house, it means there's a leak somewhere, and it could just be a small leak to start before it becomes an expensive and damaging problem.
If you know it will be a cold night, keep the cabinet doors open underneath your sinks. This may sound crazy, but there's actually a good reason for this.
Letting warm air from the house into your cabinet will allow it to circulate your pipes. The warm air prevents the pipes from freezing.
A leaking pipe
A leaking pipe can cause low water pressure because less water is flowing through to your faucets and shower heads and instead is leaking somewhere in the house. This can cause a massive issue down the line with either a burst pipe or interior damage to the house. If you can see where a pipe is leaking, make sure to call a licensed plumber to help you fix the problem. Sometimes leaks aren't always visible though, and it'll take a professional to figure out where the leak is.
What do you do if you find a leak?
Find and fix any leaks
No matter how minor a leak may seem, you must never put off fixing a leak—always address them right away.
Inspect your pipes in the spring after winter to see if there is any damage, and have all leaks repaired as soon as possible. If you don't trust yourself to do the job, call a plumber to check it out for you. Don't rest until you know that you've identified and addressed every leak and go back to enjoying your nice water pressure again.
Find your water shut-off valve
If you don't know where your water shut-off valve is, it's time to locate it now. If you ever encounter a burst water pipe or a leak, you'll want to switch off the valve immediately.
These can be found in one of these common places. The crawl space where the water line enters the home. The garage where the water line enters the wall or ceiling, near the water heater or laundry hookup, or outside near the foundation usually protracted by a clay pipe or concrete ring.