Change Your Home One Step at a Time

Change Your Home One Step at a Time

How to Clean Your Tankless Hot Water Heater's Cold Water Intake Filter

by Aiden Carroll

Tankless hot water heaters are a boon to American homeowners looking to save big on their utility bills. Tankless heaters are more efficient than their conventional cousins because they provide hot water when it is needed and don't waste energy by heating a large volume of water for no purpose.

However, tankless hot water heaters do require attention to keep them running at their optimum levels. One area that should be frequently addressed by homeowners is the cold water intake filter. This component serves as a gate to keep out potentially-damaging contaminants that might cause a clog or malfunction inside the heater. A failure to keep the filter clean and clear could result in reduce flow or even premature failure of the heater.

Fortunately, it is not difficult to maintain this filter; below is what you will need and how to perform this relatively easy task:

Tools and materials needed

  • Eye protection
  • Adjustable pliers
  • Five-gallon bucket
  • Vinegar
  • Bowl or large cup
  • Brass wire brush


1. Work with safety in mind—Though tankless hot waters do not possess a large volume of water, they are still capable of causing severe scalding injuries. Never perform any work on a tankless water heater that is still supplied by gas or electricity, and always wear eye protection in case of an unexpected spray of hot water.

2. Turn off the gas supply—Your water heater will contain a gas pipe inlet with a shut-off ball valve; in the 'on' position, the handle to the ball valve is aligned parallel with the gas pipe. Turn the handle one-quarter turn until it is perpendicular to the pipe to shut off the gas supply. Don't place too much force on the handle or fittings, or you may cause a gas leak.

3. Turn off electrical power—The hot water heater should have an electrical shut-off switch close by, but if you aren't able to locate it easily, turn off the appropriate circuit breaker at the main electrical panel.

4. Turn off the incoming cold water supply—The incoming water supply will also use a ball valve similar to the gas supply line's valve. Look for a yellow or green plastic handle, though the handle may also be brass or otherwise undistinguished. As with the gas supply, turn the handle until it lies perpendicular to the water line.

5. Turn on the hot water inside your home—After turning off the water supply, turn on your kitchen and bathroom faucets in the hot water position to bleed the water heater and lines. Leave them in the 'on' position while you work.

6. Remove the water inlet filter—The water filter should be located near the cold water shut-off valve or where the water enters the hot water heater. Position a five-gallon bucket beneath the unit to capture draining water.

The filter itself will be inside a round housing, and you may be able to remove the filter with your fingers; if not, use a pair of adjustable pliers to loosen it from the housing. Be prepared for water to drain from the hot water heater as soon as the filter is removed.

7. Clean the filter—After removing the filter, carefully inspect it for tears, cracks or holes; you will need to replace a damaged filter with a new one. Rinse the filter in a stream of running water to remove loose bits of debris, and lightly scrub it with a brass wire brush to get rid of the more stubborn particles.

After rinsing and scrubbing the filter, soak it in a bowl or cup of household vinegar for about an hour; this will remove hard water deposits that accumulate on or inside the filter. Rinse the filter with clean water after removing it from the vinegar.

8. Replace the filter—Return the clean filter to its housing, and reinstall it by carefully screwing it into position. Be careful not to cross-thread the filter threads, and merely hand tighten the filter unless the manufacturer's documentation specifies otherwise.

9. Restore the service—In reverse order from above, turn on the cold water supply, electrical power and gas supply. If the hot water heater fails to begin making hot water, check the manufacturer's manual for help or visit resources like for more tips or assistance. 


About Me

Change Your Home One Step at a Time

The best way to handle major home renovations is to take them one step at a time. Instead of trying to change your whole home at once, start small. I started with the guest bathroom, then the guest bedroom, then moved on to my kids’ rooms, my bedroom, and the living room. Now I’m working on remodeling the kitchen. I started this blog to help other people who are attempting major home renovations. I’ll show you how to change your whole home by breaking it up into manageable chunks. Wondering which kitchen counters are right for you, or how to add more space to your bedroom? We’ll go over the pros and cons of different materials and discuss DIY renovation projects. Before you know it, you’ll have created your dream home.