Hot water tap not working but cold is

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When you aren’t getting any hot water, you know the likely culprit is the water heater, but what do you do when the problem is a lack of cold water? There are only a certain number of issues that could lead to this problem. Follow these steps to figure out if it’s a minor repair you can correct on your own or if you need to call in the plumber.

1. Check the Water Main or Water Supply

Uh oh. There’s a heatwave and you’ve just spent an hour gardening. You’re looking forward to that glass of water to cool down but suddenly realize there’s no cold water coming out of the faucet. 

Before getting too far into diagnosing the problem with the tap in question, you should rule out a more widespread issue. Is hot water coming out of the tap? Are the other faucets working? What about the shower? If the answer to any of these questions is yes, you can be confident that it’s not a general water failure caused by the water heater or a problem with the water main or your water supply. 

If you’re not getting water anywhere in the house, find the water main valve—typically in the basement, under the sink, or near the water heater—and confirm that it’s open. If that doesn’t solve the issue, check with your neighbors to figure out if they’re having similar issues before contacting your water supplier.

2. Check the Shutoff Valve

The pipes to each sink in your house are outfitted with a shutoff valve that allows you to stop the water supply locally without affecting the rest of the house. If you have kids or pets, it’s possible that they inadvertently closed the valve—or, if you’ve had repair work done recently, it could be that the plumber neglected to open it back up after the job was complete. 

Under your sink, trace the pipes that supply it with water and search for a knob or lever. Turn it counterclockwise as far as it will go to confirm it’s fully open.

3. See If the Supply Line Is Kinked

Photo: Jose Luis Pelaez Inc / DigitalVision / Getty Images

While you’re looking under the sink, another potential issue to check is if the supply line (the thinner line of piping connected to the sink) has become bent or kinked. Though most newer homes feature braided steel lines that are difficult to damage, many older builds still include a more flexible copper or all-metal version that bends easily, choking the water supply. 

If yours appears to be out of shape, try manually straightening it and see if that gets the cold water running again.

4. Try the Spray Nozzle

If your faucet includes a separate spray nozzle, it’s possible that the feature’s stutter valve, which diverts the water to the nozzle when it’s in the open position, has become stuck. Try running the water through the spray valve a couple times, and see what happens. 

If you’re getting water there but not out of the faucet, it’s safe to assume the stutter valve is to blame. Turn off the flow of water to the sink using the shutoff valve, which is attached to the pipe underneath. Next, turn both the faucet and the spray nozzle on at the same time before opening the valve again—this should disengage the nozzle’s vapor lock and return water flow to the faucet.

5. Look for a Frozen Pipe

If you live in a cold climate, and you have not winterized your pipes, the most likely culprit in your cold water problem is a frozen pipe. If the sink’s pipe is located behind cabinet doors, open them up to let in a little heat from the house. 

If you regularly experience cold periods, it’s a good idea to get in the habit of leaving the cabinet open to prevent the pipe from freezing again in the future. For a little extra power, you might also use a portable heater if there’s a safe spot to put it nearby or a hairdryer. If it was frozen solid, the ice may have damaged the pipe or the faucet, so there’s a risk that thawing the pipe could lead to a leak. If this happens, it’s time to call a plumber.

6. Search for Leaks

If a pipe is leaking somewhere in your house, it could be cutting off the flow of water to the tap in question. Trace the pipes throughout your house and see if you can find evidence of a leak somewhere. There are some short-term solutions for leaking pipes that might lessen the damage, but you’re going to need to call in a plumber to get the cold water flowing again.

7. Investigate the Water Purifier

Some kinds of under-sink water filter systems can trigger an automatic shutoff to your faucet if the pressure becomes too high. If this is the reason no cold water is coming out of the faucet, you can manually set the water to bypass the unit, restoring the flow to the tap—just remember that until you correct the issue with the unit, this water will no longer be filtered.

8. Replace the Washer

Photo: Jose Luis Pelaez Inc / DigitalVision / Getty Images

In some cases, a tap can become blocked simply because the washer has loosened and dislodged, physically blocking the water flow. Turn the shutoff valve, disassemble the faucet, and replace the washer with a new one. If you get a smooth flow of water, your problem is solved!

9. Check Your Faucet Cartridge Hasn’t Gone Bad 

When your shower tap isn’t producing cold water, it’s likely a problem with the pressure-balancing valve in the shower faucet cartridge. You’ll have to turn the shutoff valve, remove the faucet handle, and take out the old cartridge—located behind the escutcheon (the metal piece used to hide the hole in your wall where the pipe comes through) and often held in place by retaining clips.

Many can be removed with a pair of pliers, but if yours requires a cartridge-pulling wrench, it may be easier to call the plumber than to do it yourself.

Know When to Bring in the Pros

Once you’ve tried all the relevant options above, it’s safe to assume that the problem is too complex for a DIY fix. The most likely cause of no cold water coming out of your faucet—especially if the blockage was preceded by a steady decrease in water pressure—is a build-up of lime scale, created by mineral deposits from hard water. 

The long-term solution will require installing a different kind of pipe, or adding a water softening system, but you’ll want to leave the determination to a trained plumber. 

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