How often should a landlord flush or drain a rental water heater?
Drain a small amount from a tank water heater a few times a year to clear sediment, and have a professional flush the whole tank on a schedule that follows the manufacturer's manual, commonly yearly. The U.S. Department of Energy's advice is to drain a quart of water from the tank every three months to remove sediment that slows heat transfer. In a rental you can build this into your turn checklist and a yearly visit, instead of hoping the tenant does it.
Why sediment matters
Minerals in water settle at the bottom of a tank heater. A layer of sediment makes the burner or element work harder to heat the water, which can mean noise, longer heating times, and a shorter life for the tank. The Department of Energy advises draining a quart of water from the tank every three months to remove it.
This applies to tank heaters. Tankless units have their own descaling steps in the manual, usually done by a technician.
A routine that fits a rental
- Quarterly partial drain: open the drain valve and fill a bucket with about a quart, per the DOE advice. Check the water for rust or grit.
- Yearly check by a plumber or maintenance person: look for leaks, rust at the fittings, a working temperature and pressure relief valve, and the age on the label.
- At every turn: do the quick drain and note the date.
Always follow the manual. Turn off the power or gas first as the manual says, and let hot water cool before you touch the drain. If you are not comfortable doing it, send the job to a vendor.
When not to flush
An old tank that has never been drained may have a valve that leaks once opened, or sediment so thick it clogs the drain. If the heater is near the end of its life or the valve is stuck, call a plumber instead of forcing it. A flush that starts a leak on an unattended heater is a bigger problem than the sediment.
If a heater is more than about a dozen years old, tell yourself to price a replacement before it fails. The repair or replace post covers that decision.
The quick drain, step by step
These steps are the common pattern for a tank heater. Your manual is the final word, and gas and electric models differ.
- Turn off the power at the breaker, or set a gas heater to its pilot or off setting as the manual describes.
- Close the cold water supply valve to the heater if the manual says to.
- Attach a garden hose to the drain valve near the bottom, and run it to a floor drain, a bucket or outdoors. The water can be hot enough to burn.
- Open the drain valve, and open a hot water tap in the unit so the tank can drain.
- Watch the water. If it runs cloudy, rusty or gritty, let it run until it clears. If it never clears, stop and call a plumber.
- Close the drain, open the supply valve, let the tank refill completely with the hot tap open until water runs steady, then restore power or gas.
- Log the date and what you saw.
Never turn the power back on to an empty tank. An electric element that heats without water burns out in moments, which turns a cheap chore into a replacement.
Who does it, and how to write it down
Tenants should not be asked to drain a water heater. Put it on your own maintenance calendar and tell tenants you will enter with notice. Each visit should record the date, the unit, what was found, and a photo of the label showing the age.
Example a made-up 6 unit building has water heaters installed 3, 5, 6, 9, 11 and 12 years ago. A yearly check logs the age of each. The two oldest, at 11 and 12 years, go on a replacement list for the capital budget, so the owner picks the timing instead of a leak choosing it.
How DoorKeeping handles it
Ask Claude or ChatGPT to create a recurring water heater work order for each unit and send it to your plumber by link. The notes and photos stay with the property, so you can see which heater is oldest when you plan next year's repairs.
Sources
- U.S. Department of Energy: Energy Saver guide (water heater sediment), read Oct 30, 2026
Questions
- How often should a water heater be drained?
- The Department of Energy suggests draining a quart every three months to remove sediment. Check the manufacturer's manual for your model.
- Can the tenant flush the water heater?
- It is better handled by the owner or a vendor. Tenants should not be asked to open a tank drain.
- Should I flush a very old heater?
- Be careful. An old tank can leak when disturbed, so ask a plumber and plan a replacement.
- Does a tankless heater need a flush?
- It needs descaling per its manual, usually done by a technician.