Symptoms
- Hot water flow is noticeably weaker than cold at the same fixture
- Cold water pressure feels normal throughout the house
- Problem affects hot water at multiple fixtures, not just one
- May have developed gradually
Likely causes
- CommonSediment buildup restricting flow inside the tankA thick sediment layer can partially block the outlet or dip tube area.
- CommonCorroded or clogged dip tube or outlet nippleMineral buildup can narrow these passages significantly over time.
- PossiblePartially closed shutoff valve on the hot water line at the tankA valve not fully open restricts flow specifically to the hot side.
- PossibleClogged aerators on multiple fixtures coincidentally, unrelated to the tankWorth ruling out before assuming it's the tank itself.
What to do
- Check that the hot water shutoff valve at the top of the tank is fully open.
- Remove and clean the aerator on one affected faucet to rule out a simple local clog.
- If multiple fixtures are affected and aerators aren't the cause, flush the tank to clear sediment.
- After flushing, test hot water pressure again at a fixture close to the tank.
- If pressure is still weak, the internal dip tube or outlet nipple may be significantly corroded or clogged.
- Compare the age of the tank and note whether this points toward it being time for anode rod or nipple service, or eventual replacement.
Tools and parts
- Garden hose (for flushing)
- Adjustable wrench (for aerators)
Water heater outlet nippleSearch: “water heater hot water outlet nipple”
When to call a pro
If flushing doesn't restore hot water pressure, a plumber can inspect and replace the dip tube or outlet fitting if they're clogged or corroded.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.