Low Shower Water Pressure
Updated February 20, 2026
Weak shower flow? Could be a clogged head, partially closed valve, worn cartridge, low house pressure, or an aggressive flow restrictor. Fix depends on whether the problem is shower-only or whole-house.
Overview
First question: is it just the shower or the whole house? Shower only means local -- clogged head, closed valve, worn cartridge, restrictive flow limiter. Multiple fixtures means systemic -- main valve, PRV, corroded pipes, or low municipal pressure. Second question: hot only, cold only, or both? Hot-side-only often points to the water heater. This guide works from simplest to most involved.
Symptoms
- Weak spray that will not rinse shampoo effectively
- Pressure was normal but gradually decreased over weeks or months -- mineral buildup or cartridge issue developing
- Only the shower is weak, other fixtures are fine -- shower-specific cause
- All fixtures in the house are weak -- whole-house pressure issue
- Low pressure hot side only -- water heater valve, cartridge, or hot-side restriction
- Uneven spray with some nozzles strong and others dead -- mineral deposits blocking individual openings
Common Causes
- Mineral deposits clogging the head -- calcium and lime block the nozzle openings gradually. Most common cause, easiest fix. White or green buildup visible around the nozzles.
- Flow restrictor -- federal regs limit shower heads to 2.5 GPM or less, many newer models 2.0 or 1.5. Removable plastic or rubber disc inside the head. Makes low-pressure situations feel even worse.
- Partially closed valve -- after plumbing work, a valve may have been left not fully open. Even a quarter turn from full open reduces pressure noticeably.
- Worn shower cartridge -- internal seals and passages wear, corrode, or accumulate minerals. Restricts flow. May also cause temperature fluctuation.
- Low whole-house pressure -- failing or misadjusted PRV, partially closed main valve, corroded galvanized pipes, or low municipal supply. Normal is 40-60 PSI.
- Corroded or undersized supply pipes -- older homes with 1/2-inch galvanized lines corroded internally. Restricts flow to the shower even when pressure elsewhere is fine.
What You'll Need
How to Fix It
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Clean or Replace the Shower Head
Easiest fix first. Unscrew the head from the shower arm (wrench with a cloth to protect the finish if stuck). Submerge in white vinegar 2-4 hours or overnight. Toothpick or needle through each nozzle to dislodge remaining deposits. Silicone nozzles? Rub with your finger to flex and clear. Reinstall, test. Still weak? The head itself may be too restrictive.
Tip: Do not want to remove it? Plastic bag of vinegar over the head, rubber band, overnight. Works for light to moderate buildup. -
Check and Remove the Flow Restrictor
Head removed? Look inside the inlet. Small plastic or rubber disc with a narrow hole (may be colored green, blue, or yellow) is the flow restrictor. Remove with needle-nose pliers or flathead. Increases flow from 1.5-2.0 GPM to 2.5+. Reinstall and test. Note: increases water consumption.
Tip: Want some restriction but better pressure? High-pressure shower heads designed for low-pressure situations. Concentrated nozzle patterns create the sensation of higher pressure without much more water. -
Check All Supply Valves
Every valve in the supply chain, fully open. Main shutoff (counterclockwise until it stops for gate, parallel to pipe for ball). Dedicated shower shutoffs behind the access panel? Check those. Hot side only? Check water heater inlet and outlet valves. Even slightly closed dramatically reduces flow.
Tip: Recent plumbing work anywhere in the house? Most likely cause. Plumbers close valves during work and do not always fully reopen them. -
Replace the Shower Cartridge
Water off. Handle off (screw under decorative cap), trim plate off, retaining clip out. Pull the cartridge straight out (cartridge puller for stubborn ones). Take the old one to the store -- Moen, Delta, Kohler, Price Pfister all use different cartridges. New cartridge in, reassemble, test. Often restores full flow and fixes temperature issues too.
Warning: Cartridges are brand-specific and often model-specific. Wrong one will not work and can damage the valve body. Brand is sometimes stamped on the trim plate or handle. -
Test Whole-House Water Pressure
Multiple fixtures affected? Pressure gauge on a hose bib ($10-15). Normal is 40-60 PSI. Below 40 explains the problem. Check the PRV (bell-shaped brass fitting on the main line). Adjustment screw on top: clockwise to increase, small turns, retest. Does not help? PRV may need replacement.
Tip: Test at different times. Normal in the morning but drops at 7-9 AM or 5-7 PM? Could be neighborhood demand, not your plumbing. -
Address Pipe Corrosion (If Other Fixes Fail)
Everything else checked and shower still weak? Supply pipes may be corroded or undersized. Common in older homes with galvanized steel. Internal corrosion narrows the pipe to a trickle even with good pressure elsewhere. Solution: replace the corroded section with copper or PEX. Requires opening the wall -- best done during a remodel.
Tip: Not ready for a remodel? A plumber can use a borescope or pressure differential test to confirm the restriction without opening the wall. Helps you plan for the right time.
When to Call a Pro
Call a plumber if you are not comfortable replacing the cartridge, if the PRV needs replacement, if you suspect corroded pipes, if pressure dropped suddenly (water main issue or broken pipe), or if one bathroom is low and you cannot find the cause.
Prevention Tips
- Vinegar clean the shower head every 3 months. Especially important in hard water areas.
- Water softener above 7 GPG. Dramatically reduces scale in heads, cartridges, and pipes.
- After any plumbing work, verify all valves fully open. Run every fixture to confirm.
- Replacing the head? Choose one designed for your pressure. High-pressure models work well in low-pressure situations.
- Replace cartridges every 10-15 years even if they seem fine. Internal buildup restricts flow so gradually you may not notice.
- Galvanized pipes? Plan for replacement with copper or PEX during renovations.