Quick Answer:
If the shower feels weak while other faucets are fine, start with simple checks: compare the flow from the shower head to the tub spout, test hot and cold separately, make sure the shower valve is fully open, and clean the shower head and inlet screen. If you recently had the water turned off or work done, flush the line for debris and consider a stuck or clogged cartridge inside the valve.
Why This Happens
- Mineral buildup or debris collects in the shower head or the small inlet screen, reducing spray even though house pressure is otherwise normal.
- A clogged diverter, cartridge, or mixing valve can limit flow to the shower while leaving sink and tub spout flow unchanged.
- Recent plumbing work, a shutoff, or a main being turned back on can send sediment into just one branch of the system. If you’ve recently had an outage, check for low water pressure after turning the water back on.
- When only the shower is affected, it often points to a local problem rather than whole-house pressure loss—think clogged head, fault in the valve, or diverter issues. If only one fixture is affected in your home, see notes about only one faucet has low water pressure for similar causes.
Step-by-Step What to Do
1. Compare shower head and tub spout flow
- Turn the tub spout on and note the flow strength. Then switch to the shower head. If the tub spout is strong but the shower head is weak, the problem is usually the shower head, diverter, or valve.
- If both are weak, you may have a valve or supply problem upstream.
2. Test hot vs cold
- Run the shower on full cold only, then full hot only. If one side is weak and the other is fine, the issue is likely on that hot or cold supply side or the cartridge inside the valve that mixes them.
3. Check the valve is fully open
- Confirm the shower control(s) are turned to the normal open position. Some valves have separate shutoff stops behind an access panel—make sure those are open if present.
4. Clean the shower head and inlet screen
- Remove the shower head (usually you can unscrew it by hand or with a wrench wrapped in cloth). Look for a small rubber or metal screen at the inlet—clean or replace it.
- Soak the shower head in white vinegar for 30–60 minutes to dissolve mineral buildup, scrub with a soft brush, rinse, and reinstall.
- Re-check flow after reassembly; many weak showers are fixed by this simple cleaning.
5. Check for debris after a shutoff or work on the water
- If you’ve recently had the water shut off or work done, turn on the tub spout and let it run for a minute to flush debris. Then test the shower head again. Sediment can lodge in the small passages of the shower head or valve.
6. Consider cartridge or valve blockage
- If cleaning the head didn’t work and the issue affects hot or cold specifically, the cartridge or mixing valve may be blocked, damaged, or worn. These parts sit behind the handle and control flow to the shower.
- Access requires removing the handle and trim plate. If you are comfortable and the shutoff is local, you can inspect for visible debris. Often the cartridge will need to be cleaned or replaced.
- If you remove the cartridge, keep track of positions and take a photo so you reinstall correctly.
What Not to Do
- Do not drill out flow restrictors in the shower head. That damages the fixture, may violate local codes, and can cause unsafe flow patterns.
- Do not crank the handle past its normal limit trying to force more flow. Forcing hardware can break the valve or cause leaks.
- Do not ignore a sudden or worsening drop in pressure. A sudden change can mean a failing valve, a major blockage, or a pipe problem that needs prompt attention.
When to Call a Professional
- If cleaning and simple checks don’t restore normal flow, a licensed plumber can inspect and replace a cartridge or valve.
- If you find leaks when removing trim or see corrosion on the valve body, call a pro—continued use can cause water damage.
- If multiple fixtures lose pressure at once, or you suspect a main supply issue, a professional diagnosis is safer.
Safety Notes
- Always shut off the local supply valves or the house main before working on a valve. Open a lower faucet first to relieve pressure.
- Protect finishes: use cloth when using tools on chrome or brass to avoid scratches.
- If you’re unsure about turning off water or removing cartridges, or if the valve is corroded and hard to remove, stop and call a professional to avoid causing a leak or injury.
Common Homeowner Questions
- Why is my shower weak but the sink is fine? Usually a clogged shower head, diverter, or valve; the sink taps are on a different branch so they stay strong.
- Will soaking the head in vinegar hurt it? No for most metal and plastic heads a 30–60 minute soak is safe; rinse well before reinstalling.
- How do I know if the cartridge needs replacing? If cleaning doesn’t help and one side remains weak or the handle feels stiff/leaky, the cartridge likely needs replacement.