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When It Is One Tap and Only One Tap

A whole house losing pressure is a different problem with a different cause. One faucet losing flow while everything else is normal is a short list, and the top of the list unscrews by hand.

Briefly

When a single faucet loses flow and the rest of the house is fine, the fault is almost always in the last two inches: the aerator first, then the supply stops beneath the sink, then the cartridge. Before any of that, note that a lavatory faucet is capped at 2.2 gallons per minute at 60 psi, so a gallon in half a minute is normal rather than slow.

Source: 10 CFR § 430.32(o), the Department of Energy water conservation standard for faucets.

FaucetMend is a referral service, not a contractor. We connect homeowners with independent contractors. Contractors are required to hold whatever credential their state or municipality demands. We carry out no work, we sell no fixtures, we do not set prices, and we never charge homeowners anything — the contractors in our network pay us when we route them a call. Nothing here is a statement about the water at any address; only a test of that water can tell you about it.

First: the aerator

The screen on the end of the spout catches everything the pipes shed and everything the water deposits. It is the most common cause of this complaint by a wide margin and the easiest thing in plumbing to check: unscrew it, look at it, rinse it, put it back.

Do it before anything else. A contractor called out for a slow tap will do this first too, and it is a poor use of a visit.

Second: hot only, or cold only

If only one side is slow, the fault is upstream of the mixing point, which usually means the shutoff valve or the supply line on that side. If both are slow together, the fault is at or after the mixing point — the cartridge, the outlet or the aerator.

That one observation cuts the possibilities roughly in half and it costs nothing to make.

Third: the shutoff under the sink

Angle stops are frequently left partly closed after other work, and older ones seize part-way. Check both are fully open, gently. The cabinet is worth a proper look while you are down there.

Fourth: the cartridge or the supply line

Debris inside a cartridge restricts flow rather than stopping it, and flexible supply lines can fail internally in a way that looks like nothing from the outside. Both are contractor work and both are ordinary.

What the tap is allowed to deliver

A lavatory faucet sold in the United States may not exceed 2.2 gallons per minute at 60 psi, a Department of Energy standard in force since 1998. A WaterSense-labeled one is held to 1.5 gpm at the same pressure, which is 32 percent below the federal maximum.

So the test is a jug and a watch. A gallon in about half a minute is a faucet doing exactly what it is permitted to do; a gallon in two minutes is not. That distinction is worth making before anybody is called, because one of the two is a repair and the other is an expectation.

Source: 10 CFR § 430.32(o), the Department of Energy water conservation standard for faucets; US EPA WaterSense, bathroom faucets.

If every tap is slow

Then this is not a faucet page’s problem. A whole-house loss of flow is a supply, pressure or main problem and it needs somebody looking at the incoming side rather than at the fixture.

Know the maker? Say so on the call.Cartridges are specific to a manufacturer, and the name on the handle is frequently the difference between one visit and two. We route you to a contractor covering your area, chosen on the ZIP code you give, free of charge to you. Faucets are simply our subject; the number itself handles any plumbing request.

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