Domakihub How to Flush a Water Heater and Extend Its Life
Clear steps to remove sediment, restore hot water output, and protect your tank.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Sediment quietly accumulates at the bottom of every storage water heater, and in Greece — where water hardness can be significant, especially in the Attica basin and on many island networks — the build-up happens faster than most homeowners expect. The result is longer heating times, higher energy bills, and a tank that fails years ahead of schedule. The video above walks through the full procedure visually; the steps below give you the precise sequence to follow safely in your home, rental property, or hotel room block.
Why Sediment Is a Bigger Problem in Greece
Hard water is common across much of Greece: calcium and magnesium minerals dissolve into the supply as it passes through limestone geology. When that water is heated, the minerals precipitate and sink to the tank floor as a white or yellowish crust. Over time this layer insulates the heating element (electric) or the burner plate (gas), forcing the appliance to run longer cycles just to reach temperature.
Holiday rentals and hotels face compounded exposure because high guest turnover means the heater rarely has idle time to cool, and the continuous throughput deposits more scale per year than a typical primary residence would. A flush once a year — or twice a year in hard-water areas — keeps the tank performing at its rated efficiency.
What to Gather Before You Start
You need a standard garden hose long enough to reach a floor drain, outdoor area, or bucket; a flat-head screwdriver or slot key for the drain valve; work gloves; and optionally a pair of channel-lock pliers if the drain valve is stiff. Electric water heaters also require you to identify the correct circuit breaker — mark it clearly if it is not already labelled. Gas heaters have a thermostat dial with a 'pilot' or 'vacation' setting you will use instead of the breaker.
How to Flush Your Water Heater: 5 Steps
- 1
Turn off the heat source
For an electric heater, switch off the dedicated circuit breaker — never flush with the element live, as exposing a hot element to air even briefly can burn it out. For a gas heater, turn the thermostat dial to 'pilot' or 'vacation' mode; this cuts the burner but keeps the pilot flame going so you do not need to relight it afterward. Allow the water inside to cool for at least an hour if the heater has recently run a full cycle, or you risk scalding when you open the drain valve.
- 2
Connect a hose and open a hot-water tap
Screw one end of your garden hose onto the drain valve near the base of the tank and run the other end to your drain point — a floor drain, a bucket, or outdoors onto permeable ground (avoid flower beds, as the sediment water is mildly alkaline). Open any hot-water tap in the building. This breaks the vacuum inside the closed system and allows water to flow freely through the hose; without it the drain will trickle or stop.
- 3
Close the cold-water inlet and open the drain valve
Turn the cold-water supply valve on top of (or beside) the heater to the closed position. Now open the drain valve — turn it counter-clockwise with your screwdriver or by hand if it has a lever. Water will begin flowing through the hose. Let the tank drain fully; a 100-litre tank typically takes 10 to 20 minutes. Watch the discharge: at first it will be cloudy or carry visible white or rust-coloured flakes — this is the sediment you are removing.
- 4
Flush with fresh water to clear remaining sediment
Once the tank is empty, briefly reopen the cold-water inlet while leaving the drain valve open. Fresh cold water entering the tank will stir up and carry out any sediment still clinging to the tank floor. Run this flush for two to three minutes until the water running out of the hose is clear. For heavily scaled tanks you may need to repeat this rinse cycle once or twice. Close the drain valve tightly when the output runs clear.
- 5
Refill, restore power, and check for leaks
With the drain valve closed, reopen the cold-water inlet fully and let the tank refill. Keep the hot-water tap you opened earlier running until water flows from it steadily without sputtering — this confirms the tank is full and all air has been purged. Only then restore power (flip the breaker back on, or return the gas dial to your normal temperature setting). Check the drain valve and hose connection for drips; a worn washer is the most common culprit and costs under two euros to replace.
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FAQ
- How often should I flush my water heater in Greece?
- Once a year is the standard recommendation, but if your municipality has notably hard water — common in greater Athens, Thessaloniki, and many Aegean island communities — twice a year is more appropriate. Holiday rental properties with high occupancy benefit from the same twice-yearly schedule.
- What if the drain valve leaks or will not open?
- Older brass drain valves sometimes seize up or weep after being disturbed for the first time in years. Apply gentle pressure with channel-lock pliers to break the seal, but do not force it. If it continues to drip after you close it, wrap the threads with PTFE (Teflon) tape or replace the valve entirely — it is an inexpensive part available at any plumbing supply shop in Greece.
- Can I flush a tankless (instantaneous) water heater the same way?
- No. Tankless heaters do not store water, so there is no sediment tank to flush. They require a descaling procedure instead: a pump circulates a dilute citric-acid or white-vinegar solution through the heat exchanger to dissolve limescale. The process is different and typically takes 45 to 60 minutes with a descaling kit.