Published November 8, 2026 • 5 min read

A homeowner on r/HomeImprovement asked a simple question this week: should they flush a 7-year-old, 50 gallon electric water heater that the previous owner never maintained? The thread landed in the weekly top ten of the subreddit, and the answers split down the middle.

One side said flush it every year, because sediment builds up, covers the lower element, and can block the dip tube. The other side said never touch a tank that has sat for years, because a disturbed drain valve can start leaking, and compared it to an automatic transmission in a car. One commenter described a 1999 tank that began dripping from the shutoff and the drain valve after a flush attempt. Another said a 25-year-old unit still works fine and has never been drained.

Both camps are describing something real. Which one is right for your house depends on three things: the age of the tank, the type of drain valve, and what your water leaves behind. In the Treasure Valley, that last one matters more than most people expect.

Why the Internet Can't Agree on Flushing

The "leave it alone" crowd has seen a real failure mode. Old tanks, especially those with plastic drain valves, can start to weep once someone opens and closes the valve for the first time in a decade. That is a valve problem, not a flush problem, but the timing makes the flush look guilty.

The "flush it yearly" crowd has seen the other failure mode. Sediment piles up, the lower element ends up buried, and a unit that could have lasted another five years fails early. A commenter who pulled a failed element from a sludge-packed tank said the coating had been eaten away before it shorted.

A 7-year-old tank is not an antique. Most manufacturers rate tanks for 8 to 12 years, which puts it in the middle of its life, and that is exactly when a first flush is the most useful.

What Hard Water Leaves Inside the Tank

Here is the water bridge. Boise water commonly tests at 10 to 15 grains per gallon (gpg) and Meridian at 12 to 17 gpg, which counts as hard to very hard. When that water is heated, calcium and magnesium come out of solution and settle as scale and sediment on the bottom of the tank. Electric heaters are hit twice because the scale also coats the heating elements.

Signs that sediment is already there:

If you see two or more of those on a tank that was never flushed, the sediment layer is probably not small. We covered the cost side in our guide to hard water scale in water heaters.

A Safer First Flush, Step by Step

  1. Check the drain valve first. A brass valve is a good sign. A plastic valve that looks brittle is a reason to call a plumber or have a replacement ready.
  2. Turn off the power. For electric, flip the breaker. For gas, set the control to pilot. Never run an element in an empty tank.
  3. Shut off the cold inlet and open a hot faucet upstairs so air can enter the lines.
  4. Attach a hose with a strainer or bucket at the end. One commenter was surprised by how many small rocks came out. A bucket shows you what is really in there.
  5. Drain slowly. If flow stops, the valve is clogged with sediment; do not force it.
  6. Refill completely before the power goes back on.

Not sure about your tank? Our guide to a water heater flush before winter in Boise covers the routine for a unit that has been maintained. If you just bought the house, start with the new homeowner water checklist.

The Anode Rod Is the Part Nobody Mentions

One commenter pointed at the real maintenance item: the sacrificial anode rod. It corrodes in place of the tank steel, and hard water and heat wear it down faster. A rod that has been used up leaves the tank wall exposed. For a neglected 7-year-old tank, an inspection or replacement is often worth more than the flush itself, and it is a plumber job if the rod is tight or hard to reach.

Where a Softener Fits In

A softener will not clean a tank that is already full of sediment. What it does is remove most of the calcium and magnesium before the water ever reaches the heater, so the next 7 years look very different from the last 7. A quality system typically runs $2,500 to $4,500 installed in the Treasure Valley. If your tank is at the end of its life, that decision is easier to make before you buy the replacement, not after.

If you already own a softener, make sure it is working. Our five-minute hardness test is in this guide. And if you are not sure what your water measures, a free test at your tap gives you a real number to work from.

Frequently Asked Questions

Often yes, but slowly and with a plan. A tank that is 5 to 8 years old in a hard water area usually has a sediment layer on the bottom, and flushing removes much of it. The risk is an old drain valve that leaks or clogs once it is opened, so have a replacement valve and a bucket ready, and call a plumber if the valve is plastic and brittle or the tank is past 12 to 15 years.
Boise water commonly tests at 10 to 15 grains per gallon and Meridian at 12 to 17. Heating that water pushes calcium and magnesium out of solution, and the scale settles on the bottom of the tank and coats electric elements. More sediment means less hot water capacity, longer heating cycles, and a rumbling or popping sound as water bubbles under the scale.
Yes. Turn off the breaker before you drain any water, and never switch it back on until the tank is full again. Elements that run uncovered can burn out within seconds. For a gas unit, set the control to pilot or off first.
A softener removes most of the calcium and magnesium before the water reaches the tank, so far less scale forms. It will not remove sediment that is already there, and the tank still needs an occasional check. Our free water test shows your actual hardness at the tap so you can decide with real numbers.

Know Your Water Before You Touch the Tank

We test hardness at your tap and tell you plainly what your water is leaving in your heater. No pressure, no pitch.

Schedule Free Test Call (208) 968-2771