Four DIY Fixes for Slow Hot Water (and When to Call a Pro)

If it seems like it takes forever for your water to heat up when you turn it on, you might be worried you have a big problem with your water heater. Before you call in a repair professional, however, it's worth trying a little DIY troubleshooting. In some cases, you can fix your slow hot water issues yourself, with minimal expertise.

Here are four ways to fix the simplest causes of slow hot water, and some advice on when you should admit defeat and call a professional.

Check your valves

The number one reason your hot water pressure is suddenly dropping is because a valve has been accidentally left partially closed or been bumped partly closed. Sometimes you can turn a valve accidentally while cleaning or moving things around near the valve without realizing it. If you have one faucet or fixture affected by slow hot water, check the hot water valve connected to the sink, shower, or whatever other fixture. To make sure it's full open, turn the hot water valve to the left, or in line with the pipe if it’s a lever.

If the hot water everywhere in your house is slow, check the outflow valve from your hot water heater. Make sure it’s all the way open, with the lever in line with the outflow pipe. If you have a water pressure gauge or other internal valves that control the flow of water to your hot water heater (or from it), this can also be the source of your slow hot water woes.

Check your fixtures

Sometimes, the issue with your slow hot water is at the point of usage. Your faucet or shower head can be an impediment to your hot water heating up if there are malfunctioning low-flow washers or other issues with clogging. Because your fixture needs to draw water through pipes from your water heater, the slower the water moves through the fixture, the longer it will take for the hot water to arrive at the point of use. You can swap a showerhead or a faulty faucet yourself with a few simple tools, but make sure to shut the water off to the fixture you’re changing out before removing it.

Check your filters

If you have hard water, you might have too much build-up in your filter, causing water to flow to or from your hot water heater more slowly. Depending on what type of hot water system you have, you might have a specific filter just for your water heater. Make sure to follow manufacturer instructions when checking and replacing filters to avoid causing a flood—and before you do anything, make sure that the inflow valve for the filter you’re working on is in the “off” position.

Check your insulation

If you have uninsulated pipes bringing water away from your hot water heater, your water might be cooling down on the way to your fixture, especially as the weather cools down outside—typically, water pipes in basements and crawl spaces are exposed to colder temperatures than pipes in the interior of your house. Take a look at your exposed pipes to see if the insulation is damaged, or if they are uninsulated altogether. You can DIY pipe insulation on exposed pipes by adding foam pipe wrap or foiled fiberglass tape. If you suspect that there’s a larger issue with pipes traveling uninsulated through walls, like in an older home, having a plumber take a look is a good idea. Which brings me to...

When to call a pro for your hot water issues

If you have checked all of your valves, filters, insulation, and fixtures and you’re still having an issue with slow hot water, you might need to contact a pro. Clogged water lines, damaged or corroded pipes, issues with the main water line feeding your house, or improperly installed water lines can all cause your hot water to run more slowly.

You should also contact a plumber if you notice water anyplace it shouldn’t be, especially if you can’t find its source. These aren’t things that the average homeowner is qualified to fix, given the risk of flood associated with plumbing projects, especially ones involving your main water line.