Yes, you can absolutely flush a tankless water heater yourself. It is a very manageable DIY task that takes about 45 to 60 minutes and requires only a few basic tools. Regular flushing helps prevent mineral and scale buildup, extending the lifespan of your unit.
Check with a local pro for your specific job. Cost Insights: Tank water heater flushing costs $110 to $200, while tankless models run $150 to $250 due to their more complex components. Your tank size and household hot-water use affect flush time, since larger tanks take longer to drain and refill.
The best tankless water heater flush solution depends on your priorities: food-grade white vinegar (for safety and affordability) or commercial descalers like QwikDescaler+ or Hercules Haymaker (for speed and visual color indicators). Never use harsh chemical acids, as they can damage your heat exchanger.
If a standard showerhead is fitted, it will use around an extra half a gallon each minute, accounting for a 25-gallon emittance every 10 minutes, or 50 gallons throughout a 20-minute shower. *1 gallon = 4.54 litres.
The 4-minute shower rule is a sustainability and cost-saving initiative advising people to limit their daily showers to four minutes or less. This practice helps conserve water, reduce energy used for heating, and lower household utility bills by limiting consumption to approximately 36–40 liters (roughly 9.6–10.5 gallons) per shower.
When your hot water only lasts 15 minutes, it usually means your water heater is struggling to heat water fast enough or the hot water is mixing with cold water. The most common culprits are a broken dip tube, a faulty lower heating element (on electric tanks), or excessive sediment buildup.
If the gas burner or electric heating elements come on during the flushing process, the water heater can be damaged, requiring repair or replacement. Some manufacturers will recommend turning the gas off completely during this process, others may recommend setting the gas valve to the “pilot” or “vacation” setting.
Water main flushing is the process of cleaning the interior of water mains and removing any accumulated sediment by sending a rapid flow of water through the mains. This rapid flow disrupts any sediment that may accumulate in the main over time, allowing us to filter and remove it.
The most reliable water heaters depend on the type of unit you need. For traditional tank water heaters, plumbers and industry experts consistently rank A.O. Smith, Bradford White, and Rheem as the most dependable brands. For tankless systems, Navien and Rinnai are the top-rated choices.
Flushing tankless water heaters whose heat exchangers are blocked by the lime scale is very important and must be done before something happens. If you don't flush the water heater, the heat exchanger can be damaged as not enough water will pass through and cool it down.
Here is a simple way to decide: Choose Navien if you want the highest efficiency, longest warranty, and built-in recirculation. Choose Rinnai if you have a large household and need the highest flow rates. Choose Rheem if you want a reliable brand at a lower price point.
White distilled vinegar is our favourite choice for cleaning due to its high acidity and low cost. It's great at removing grease from surfaces, as well as getting rid of smells.
Plumbers often hesitate to recommend tankless water heaters because they act like high-performance sports cars. Unlike traditional tank models that are "workhorses" and can function while mostly ignored, tankless units require precise installation, regular maintenance, and are highly sensitive to mineral buildup.
Flushing a tankless water heater typically takes 45 to 60 minutes. The entire maintenance process—including setup, circulating the descaling solution, rinsing the system with fresh water, and draining—usually takes about 1 to 1.5 hours from start to finish.
Here are some common reasons why your tankless water heater might not be working and how you can troubleshoot these problems.
The "135-degree rule" in plumbing states that the total (aggregate) horizontal change in direction for a drainage pipe—specifically trap arms—cannot exceed 135 degrees between the P-trap and the vent. Exceeding 135 degrees (such as using three 45-degree bends or a 90 and two 45s) requires a cleanout because sharp turns hinder flow and cause clogs.
Apply Vinegar as a Dissolving Agent
One of the most popular methods for removing limescale is using vinegar as a dissolving agent. All you need to do is pour vinegar down your drain and let it sit overnight. The acidity of the vinegar will break down the calcium carbonate and dissolve any buildup in your pipes.
Flushing is usually commenced two weeks before harvest. If the plant has an eight-week flowering period, the flushing will need to take place six weeks after the start of the flowering stage. It is best to take a close look at the trichomes on your plant to assess when your cannabis is likely to be ready for harvest.
If your water heater is 10 years old and has never been flushed, it is generally best to leave it alone. Flushing an older, neglected tank can dislodge sediment, which might permanently unseal old, brittle valves or cause the tank to leak.
It takes about 30 minutes to 60 minutes to flush the water mains on each street.
In short, draining removes water. Flushing removes sediment, and that makes all the difference.
This problem usually comes down to capacity, heat production, or mixing issues inside your plumbing system. Sometimes the fix is simple, like adjusting your water heater temperature or flushing out sediment. Other times you may need a new mixing valve, an element replacement, or a different size water heater.
A 50-gallon water heater typically provides 15 to 25 minutes of continuous hot water for a single shower. Because you mix hot water with cold, you generally get about 70% to 80% of the tank's total capacity before the water turns lukewarm.
A 10-minute shower typically uses 12 to 25 gallons of hot water, depending on your showerhead's flow rate and how hot you keep the water.