Low water pressure at a commercial faucet is most often caused by a clogged aerator or spout screen, a stop valve under the sink that is partly closed, or debris caught in the faucet’s cartridge or inlet screens after plumbing work. Check those first; if only the hot side is weak, or every faucet in the building is weak, the cause is in the supply, not the faucet.
A weak faucet slows warewashing and makes staff skip handwashing, and a hand sink has to stay usable: the Food Code asks that a handwashing sink be kept accessible at all times for employee use (12VAC5-421-2310 in Virginia’s adoption). This guide goes through the checks in the order that finds the problem fastest, for compartment sink faucets, pedal valves and hand sink faucets such as our commercial hand sink faucet.
Step 1: Is it one faucet or the whole building?
Open another faucet nearby. If every fixture is weak, the problem is the building supply: the main valve, a pressure reducing valve, the water meter, or the utility. Call a plumber or the water company. If only one faucet is weak, keep going.
Step 2: Hot, cold or both?
Run hot only, then cold only.
- Both weak: the faucet outlet is restricted (aerator, spout screen, spout) or both stops are partly closed.
- Only hot weak: check the hot stop valve, the water heater outlet valve, and any mixing or tempering valve on the hot line. Sediment from the water heater often settles in the hot side of the faucet.
- Only cold weak: check the cold stop valve and the cold inlet screen.
Step 3: Clean the aerator or spout screen
Most hand sink and gooseneck faucets have an aerator or a screen at the tip of the spout. Unscrew it (wrap the jaws of the pliers to protect the finish), rinse out grit, and soak scale off in vinegar or a descaler. Put it back hand tight. If flow comes back, you have found it. This is the most common fix, especially after any plumbing work upstream, when loose debris is flushed into the faucet.
Some faucets are built with a flow limiter: the TWF-12 wok faucet on our site, for example, is listed at 2.2 GPM. A faucet with a low rated flow can feel weak next to an older faucet; check the rating on the product page before treating it as a fault.
Step 4: Check the stop valves and supply lines
Under the sink or behind the backsplash, check that both stop valves are fully open; staff sometimes close them to stop a drip and forget. Look for kinked or crushed braided supply lines, especially behind sinks that were pushed back against the wall.
Step 5: Check the cartridge or stem
Each handle opens a valve: a ceramic disc cartridge on many current faucets, or a stem and washer on older ones. Our HFC-35 hand sink faucet is a two handle deck mount model for 4 inch centers, and our 8 inch center wall mount faucet uses ceramic cartridge valves.
Shut off the water, remove the handle and cartridge per the manual, and look for grit or scale on the inlet. Rinse it clean. A cracked or worn cartridge, or one that turns but does not open fully, needs replacing.
Step 6: Pedal and knee valves
Hands-free hand sinks often run through a foot or knee pedal valve. These have their own inlet screens and valves. If a pedal sink is weak but the same water works elsewhere, check that the pedal opens fully, that the screens in the valve body are clean, and that the supply lines between the valve and the faucet are not kinked. We carry a dual knee pedal valve and a dual foot pedal control for hot and cold water; both sit between the supply and the faucet.
Step 7: Pre-rinse units and long spouts
Pre-rinse spray heads have small holes that scale over. Soak the spray face in descaler and clear the holes with a soft brush. Swing spouts that leak at the swivel also lose pressure at the outlet; replace the O-rings.
When the faucet is the problem
If the faucet is old, corroded or the cartridge is no longer made, replacing it is often quicker than repairing it. Measure the distance between the supply holes, center to center (4 or 8 inches on most commercial sinks), and whether the faucet mounts on the deck or on the backsplash wall, before you order. See our commercial sink faucets, faucets and plumbing supplies, and hand sinks that come with a faucet.
What to buy
- For a hand sink with 4 inch deck holes: the HFC-35 replacement faucet. For 4 inch wall holes: the HFC-4 wall mount gooseneck with wrist-action handles.
- For a compartment sink with 8 inch wall supply: our wall mount faucet with a 6 to 16 inch swing spout.
- For hands-free use: a knee or foot pedal valve.
Faucets ship with freight included to the 48 contiguous states, and as non-powered items they have a 14 day return window from delivery.
Frequently asked questions
Why did my faucet lose pressure after a plumber worked on the line?
Debris loosened by the work often lodges in the aerator, spout screen or cartridge inlet. Clean those first.
Why is only the hot water weak?
Check the hot stop valve, the water heater outlet valve and any mixing valve. Sediment from the water heater collects on the hot side.
Can I remove the aerator to get more flow?
The aerator or flow limiter is part of the faucet’s design and may be required by your local code. Clean it rather than removing it.
Your local plumbing inspector and health department have the final say on hand sink and faucet requirements.