How to Increase Water Pressure in an Upstairs Bathroom

The water pressure on an upper floor will always be lower than the pressure at the source. This is because water loses pressure for every foot of pipe, and the loss becomes more significant in vertical piping than in horizontal piping, meaning the trip to the second floor alone will strip water pressure. This can manifest in trickling showers and low flow at sinks. Luckily, there are ways to increase the water pressure to upstairs floors so that showers spray at full force.

There are a couple of things that can contribute to low water pressure. First off is the length of pipe the water has to flow through, and how much of that pipe is vertical. An upper floor is at a natural disadvantage in this case.

The number of restrictions in the line will also interrupt flow. Lines should be at least 1/2 inch with as few elbows as possible, valves should be fully open and in-line filters should be be kept clean. Any plugging or buildup in the lines will also restrict flow.

The first thing to check is whether enough water pressure is available on the second floor. This involves making sure nothing is using water at the time, then checking the pressure with a test gauge at upstairs faucets. Active dishwashers, laundry machines, outdoor hoses and other faucets can pull water from the system, further reducing the pressure that's available to push water to an upper floor.

Once nothing else is draining the system, check the upstairs faucets and showers. If the pressure is adequate, you can make it work by using the upstairs bathroom facilities when nothing else is running.

If the pressure isn't adequate, the next step is to remove the water restrictors in the upstairs faucets and showerhead. Most water fixtures come with a small disc inside that reduces water usage; their main purpose is for large municipal systems. In an individual home where water pressure may already be low, these discs can be removed with a flat-head screwdriver to increase the cross-sectional area of flow. This will help improve water pressure and sometimes can solve the problem entirely.

If the water pressure upstairs is still low, check the water pressure regulator. The pressure can be increased by adjusting the regulator to a higher pressure. This will increase water pressure to the entire house, so be sure to do it in small increments to avoid potentially blowing out weak spots or damaging attached fixtures.

Loosen the nut with a wrench on top of the valve to access the adjustment screw; then turn the adjustment screw clockwise with a screwdriver to increase the water pressure. In some cases, a secondary pump can be added if there are reasons the water pressure should not be increased above a certain limit.

Low water pressure can be the result of excessive buildup inside pipes as well. Check showerheads and faucets for mineral buildup and clean out filters and tips using a white vinegar soak by submerging the pieces in white vinegar and allowing them to sit overnight.

Robinson Plumbing explains that if there's buildup in the piping that's restricting flow, the pipe may need to be replaced by a professional. Contact a plumber for assistance with large plumbing replacement jobs, unless you have specific plumbing experience.