Flow rate, not just water pressure, determines how a faucet or shower actually performs.
Flow rate is how much water a fixture delivers per minute, measured in gallons per minute (GPM) in the US or litres per minute (L/min) in the UK. US federal standards cap kitchen and bathroom faucets at 2.2 GPM (8.3 L/min) and showerheads at 2.5 GPM, with WaterSense-labeled efficient models at 1.5 GPM (bathroom) and 2.0 GPM (shower) or lower. Handmade faucets without a built-in restrictor, including Insideast's, typically run higher, around 8 to 12 L/min for kitchen use and 4 to 6 L/min for bathroom use, depending on home water pressure.
Flow rate and water pressure get used interchangeably, but they measure different things. Pressure is the force pushing water through the pipe, measured in PSI or bar. Flow rate is the actual volume that comes out the other end in a given time, measured in GPM or L/min. A fixture can have strong pressure behind it and still deliver a modest flow rate if it has a restrictor or aerator built in, and a fixture with average pressure can still feel strong if the spout design concentrates the flow well.
This guide covers what flow rate actually means, the standard rates by fixture type in both US and UK units, how to measure your own fixture's flow rate at home, how to increase it when it's genuinely too low, and how flow rate connects to water conservation standards on both sides of the Atlantic.
- Flow rate (GPM or L/min) measures volume delivered over time; pressure (PSI or bar) measures the force behind it. They are related but not the same thing.
- US federal maximums: 2.2 GPM (8.3 L/min) for kitchen and bathroom faucets, 2.5 GPM for showerheads. WaterSense-labeled fixtures go lower: 1.5 GPM (bathroom faucet), 2.0 GPM (shower).
- Handmade faucets without a built-in aerator, including Insideast's, run at the higher, unrestricted end of the range unless a standard aerator is added.
- You can measure your own flow rate at home in under a minute with a container and a stopwatch, no tools required.
- The UK's Building Regulations Part G uses a whole-dwelling calculation rather than a flat per-fixture cap, so the "right" flow rate depends on the rest of the home's fittings, not one fixed number.
What flow rate actually means
Flow rate is the volume of water a fixture delivers in a fixed amount of time. In the US, it's measured in gallons per minute (GPM); in the UK and most of Europe, it's litres per minute (L/min). One US gallon is roughly 3.79 litres, so a fixture rated at 2.2 GPM is delivering approximately 8.3 L/min, the two figures describing the exact same flow.
Flow rate is not the same measurement as water pressure, even though the two are connected. Pressure, in PSI (pounds per square inch) in the US or bar in the UK, is the force pushing water through the pipe before it reaches the fixture. Flow rate is what actually comes out, which depends on pressure but also on the fixture's internal design, aerator, and any restrictor fitted. Two faucets on the same water line, at the same pressure, can have noticeably different flow rates purely because of how they're built.
Standard flow rates by fixture type
Regulatory maximums exist for mass-produced fixtures sold in the US, set out by federal standard and the voluntary WaterSense program. Handmade fixtures without a built-in restrictor, the kind Insideast makes, typically run at the higher end of what's physically possible for their size, since there's no aerator artificially capping the flow.
| Fixture | US federal max | WaterSense efficient | Insideast unrestricted |
|---|---|---|---|
| Kitchen faucet | 2.2 GPM (8.3 L/min) | No official label; efficient models run 1.5 to 1.8 GPM | Approx. 8 to 12 L/min (2.1 to 3.2 GPM) |
| Bathroom faucet | 2.2 GPM (8.3 L/min) | 1.5 GPM (5.7 L/min), min. 0.8 GPM at 20 psi | Approx. 4 to 6 L/min (1.1 to 1.6 GPM) |
| Showerhead | 2.5 GPM | 2.0 GPM (7.6 L/min) or lower | Depends on head style; see the shower heads guide |
| Pot filler | No dedicated federal cap | Not covered by WaterSense | Approx. 8 to 12 L/min |
A gap worth being upfront about: an unrestricted 10 to 12 L/min kitchen faucet sits above the US federal 8.3 L/min cap that applies to compliant, aerator-fitted fixtures. That's not a defect, it's the difference between a mass-produced faucet sold with a built-in restrictor and a handmade one sold without. If a project needs to meet a specific code-compliant flow rate, a standard aerator can be fitted at installation to bring any faucet down into the required range. Left as supplied, the fixture will simply flow at the higher, unrestricted rate that home water pressure allows.
External Reference
US federal standards, in effect since 1994, cap both kitchen and bathroom faucets at 2.2 GPM (8.3 L/min) at 60 psi, and showerheads at 2.5 GPM. WaterSense-labeled bathroom faucets go lower, capping at 1.5 GPM with a 0.8 GPM minimum to ensure adequate flow at lower pressure.
How to measure your own flow rate
Measuring flow rate takes under a minute and needs nothing more than a container of known volume and a way to time it.
Get a container and a timer
A 1-litre measuring jug works for a UK reading; a 1-gallon container works for a US reading. Any phone's stopwatch is accurate enough.
Turn the fixture on fully and time the fill
Run the faucet or shower at full flow into the container and note exactly how many seconds it takes to fill.
Convert to a per-minute rate
Divide 60 by the number of seconds it took to fill the container. If a 1-litre jug fills in 6 seconds, the flow rate is 60 ÷ 6 = 10 L/min. If a 1-gallon container fills in 30 seconds, that's 60 ÷ 30 = 2 GPM.
Run the test two or three times and average the results, since household pressure can fluctuate slightly between readings, especially if another fixture is in use elsewhere in the home at the same time.
How to increase flow rate
A genuinely low flow rate, well below the figures in the table above, is almost always one of three things: a clogged aerator, a partially closed shutoff valve, or a home-wide pressure problem that isn't specific to that one fixture.
Start with the aerator, the small mesh screen threaded into the spout tip. Unscrew it by hand or with pliers wrapped in a cloth to avoid scratching the finish, and check for visible mineral buildup or debris. Soaking it in white vinegar for a few hours and rinsing clears most sediment; a warped or damaged aerator should simply be replaced. Next, check the shutoff valves under the sink are turned fully open, since a valve only partly open restricts flow even when everything else is functioning correctly.
If flow is still weak after both checks, and a nearby fixture on the same line also runs weak, the problem is upstream of the faucet itself, not the faucet. That points to a whole-home pressure issue rather than anything fixable at the tap. Our guide to increasing water pressure in your shower walks through the supply-side causes, from flow restrictors to valve problems to aging pipes, in the order they're worth checking.
Water conservation standards: US and UK
The US and UK approach water efficiency differently, which matters if a project needs to meet a specific standard rather than just a sensible flow rate.
In the US, the EPA's WaterSense program sets flat, per-fixture maximums that a labeled product must meet: 1.5 GPM for bathroom faucets, 2.0 GPM for showerheads. Kitchen faucets have no dedicated WaterSense specification, so the federal 2.2 GPM standard is the applicable ceiling. Meeting these numbers is a simple, fixture-by-fixture check.
The UK works differently. Building Regulations Part G sets a whole-dwelling target, commonly 125 litres per person per day nationally, with some local authorities in water-stressed areas requiring a stricter 110 litres per person per day. Rather than capping each fixture individually, the fittings-based calculation method adds up the expected daily use of every tap, shower, bath, and appliance in the home to check the total against that target. Basin and kitchen tap flow rates in the 5 to 8 L/min range and shower flow rates around 8 to 10 L/min are commonly used inputs in that calculation, but the compliant number for any specific project depends on what else is specified elsewhere in the dwelling, so it's worth checking against the official calculator rather than treating any single figure as a fixed rule.
External Reference
UK Building Regulations Approved Document G sets a water efficiency target, commonly 125 litres per person per day, calculated either from the installed fittings or from a water use calculator, rather than a single fixed maximum flow rate applied to every tap.
Aerators are the simplest way to hit either standard without changing how a fixture feels day to day, since they mix air into the stream to preserve the sensation of pressure at a genuinely lower flow rate. For a full breakdown of how a solid brass shower head performs at different flow rates, including outdoor and rain shower options, see the complete brass shower heads guide. For a kitchen fixture with a different flow profile entirely, the pot filler taps guide covers what to expect from that style specifically.
Frequently Asked Questions
Common Questions About Faucet Flow Rate
What is the max flow rate for kitchen faucets?
In the US, federal standards cap kitchen faucets at 2.2 gallons per minute (8.3 litres per minute) at 60 psi. There is no separate WaterSense label for kitchen faucets, so 2.2 GPM is the ceiling for compliant models, though efficient aerated models often run 1.5 to 1.8 GPM. Handmade faucets without a built-in aerator or restrictor can flow higher than this, since the cap applies to the fitting as manufactured, not to unrestricted artisan fixtures.
How do I increase my faucet's flow rate?
Unscrew the aerator from the spout tip and check for mineral buildup or debris, since a clogged aerator is the most common cause of weak flow. Soak it in vinegar and rinse, or replace it if damaged. If flow is still weak, check the shutoff valves under the sink are fully open, and rule out a whole-home pressure issue by testing a nearby fixture. For a full breakdown of pressure-specific causes and fixes, see our water pressure guide.
Is a higher flow rate always better?
No. Above a certain point, more flow just means more water down the drain without a noticeable difference in how a task feels, since faucet aerators mix air into the stream to maintain the sensation of pressure at a lower actual flow. A well-designed 1.5 GPM bathroom faucet or 2.0 GPM showerhead can feel as strong as a fixture using nearly double the water.
Do Insideast faucets have flow restrictors?
Insideast faucets are handmade and generally sold without a built-in flow restrictor, so they run at the higher, unrestricted end of the typical range, roughly 8 to 12 litres per minute for kitchen faucets and 4 to 6 litres per minute for bathroom faucets, depending on home water pressure. A standard aerator can be added at installation if a lower, code-compliant flow rate is required.
What is a good flow rate for a shower?
In the US, WaterSense-labeled showerheads use 2.0 gallons per minute (7.6 litres per minute) or less, versus the federal maximum of 2.5 GPM for standard models. In the UK, water efficiency calculations commonly use showerhead figures in the 8 to 10 litres per minute range. Anything close to these figures is considered efficient without a noticeable drop in shower quality.
Every Insideast faucet, shower head, and pot filler is handmade in solid, unlacquered brass, sold unrestricted by default with a standard aerator available on request. Browse the full faucet collection, or see the shower systems collection for head and system options.
