Hot water pressure is often lower than cold because of sediment or scale in the water heater, a partly closed valve on the heater, or mineral buildup inside the hot water pipes. If the problem shows up at every faucet, the cause is usually at or near the water heater.
Check if It Is Everywhere or One Spot
Turn on the hot water at several faucets and showers. If only one fixture has weak hot water, the problem is likely in that faucet’s cartridge, aerator, or supply line. If every fixture is weak on the hot side, look at the water heater and the main hot line.
Common Causes at the Water Heater
- Sediment buildup: minerals settle in the tank and can clog the outlet or dip tube.
- A partly closed valve: the cold supply valve on top of the heater controls flow into the tank and out to the house.
- A failing dip tube: broken pieces can travel into pipes and block aerators.
- Heat traps or fittings: connections on top of the heater can become restricted.
Buildup in Hot Water Pipes
Heat speeds up mineral buildup, so hot water lines, especially older galvanized steel pipes, can narrow faster than cold lines. This often develops slowly over years.
What You Can Check
Make sure the valve on the cold line into the heater is fully open. Clean aerators and showerheads and look for white or tan flakes, which can point to sediment or a broken dip tube. Avoid opening the heater’s drain valve on an older tank yourself, since it can stick open or leak.
If the heater is noisy or slow to heat as well, sediment is a likely cause.
When hot water is weak throughout the house, having the heater flushed and inspected can help restore flow. If you suspect older pipes are the problem, you can get the hot water lines checked by calling (833) 603-1840.