Why Is the Hot Water Pressure Low in My Kitchen Sink?
Noticing that your hot water pressure is low in the kitchen sink—while the cold water flows just fine—can be frustrating. Whether you’re trying to wash dishes, rinse vegetables, or fill a pot, weak hot water can slow down your routine. Fortunately, this issue is both common and fixable. But before solving it, it's important to understand where the problem is coming from.
Let’s look at why hot water pressure drops in kitchen faucets, what causes it, and how you can fix it—or when to call a professional plumber.
Hot Water vs. Cold Water: Why Only One Is Weak?
If only the hot water pressure is low in your kitchen faucet—but the cold side works properly—then the problem is isolated within the hot water line or faucet components. This rules out main supply issues and points to either:
- A problem at the point of use (the faucet or tap)
- A localized plumbing issue in the hot water supply line
- Or something related to your water heater
By narrowing down which fixtures are affected, you can better understand whether the issue is minor—or part of a bigger system problem.
Most Common Causes of Low Hot Water Pressure in the Kitchen Sink
- Clogged Faucet Aerator
The most common reason for low hot water pressure in kitchen faucets is a blocked aerator. Over time, mineral deposits, sediment, or debris can clog the small mesh screen at the tip of the faucet. Since hot water tends to carry more dissolved minerals, this side is affected more often.
What to do: Unscrew the aerator, clean it, and rinse thoroughly. You may notice an immediate improvement.
- Sediment or Debris in the Cartridge
Inside modern kitchen faucets is a cartridge that controls water flow and temperature. If sediment from the water heater reaches the hot line, it can partially block the cartridge and reduce flow only on the hot side.
What to do: Shut off water to the faucet, remove the handle and cartridge, and check for visible buildup. Some cartridges can be cleaned; others may need to be replaced.
- Partially Closed Valve Under the Sink
Each water line under the sink typically has a shut-off valve. If the hot water valve is partially closed—whether accidentally or due to aging hardware—it will restrict flow to the faucet.
What to do: Locate the valve and turn it fully open. If it’s hard to move or corroded, it may need to be replaced.
- Supply Line Obstruction
The flexible or rigid pipe that connects your faucet to the hot water valve can become bent, kinked, or clogged. This is more likely if recent plumbing work was done under the sink.
What to do: Inspect the hot water line under the sink for sharp bends or visible damage. Replacing or repositioning the supply line may resolve the issue.
- Sediment from Water Heater
If hot water pressure is low in multiple fixtures, the issue may originate at your water heater. Sediment buildup inside the tank or near the outlet can reduce flow to the entire system. The kitchen faucet, due to its design, may show symptoms first.
What to do: Try flushing the water heater (if it hasn’t been done in over a year). If the unit is older or still underperforms, professional service may be needed.
Why Is the Hot Water Pressure Low Only in the Kitchen Sink?
This type of problem often points to:
- A fixture-specific issue (aerator or cartridge)
- A local valve or supply line problem under the sink
- Or buildup caused by aging pipes or minerals from hard water
Since other faucets likely draw hot water from the same source, isolated pressure drops usually mean the kitchen fixture needs inspection—not the whole system.
When to Call a Professional Plumber
If you’ve already:
- Cleaned the aerator
- Checked under-sink valves
- Replaced or inspected the cartridge
- Flushed the water heater
...and the hot water pressure in your kitchen sink is still low, it’s time to call a professional. The issue may lie deeper in the plumbing system, behind walls, or within corroded or scaled pipes.
At Fly Plumbing, we specialize in pinpointing causes of low hot water pressure, whether they’re at the faucet or further upstream. We’ll inspect your fixture, test the flow rate, and restore full functionality with minimal disruption.
Frequently Asked Questions
Why is my kitchen sink's hot water pressure low but the cold is fine?
This usually points to a local issue like a clogged aerator, blocked cartridge, or partially closed shut-off valve. Since cold water flows freely, the main supply is likely fine.
Can a dirty aerator cause low hot water pressure in the kitchen faucet?
Yes. Mineral buildup in the aerator can restrict hot water flow. Removing and cleaning it is often a quick and easy fix.
What if the hot water pressure is low in the kitchen sink even after cleaning the aerator?
If cleaning doesn’t help, the problem could be in the faucet cartridge, the supply line, or further upstream in the plumbing or water heater.
