{"title":"How to Flush a Water Heater","canonicalUrl":"https://www.showmestepbystep.com/home-improvement/how-to-flush-a-water-heater","category":{"slug":"home-improvement","name":"Home Improvement"},"creator":{"name":"Word of Advice TV","channelUrl":"https://www.youtube.com/channel/UCekKmUEJxBRx5tI1tUyHOqA","sourceVideoUrl":"https://www.youtube.com/watch?v=Fe-vjR1h1yw"},"tldr":"Flush and drain a water heater with a garden hose. Set gas to pilot, shut the cold supply, drain the tank, then pulse the water back on to clear sediment.","totalDurationSeconds":858,"difficulty":"medium","tools":["Garden hose","Flathead screwdriver","Pipe wrench","Bucket"],"materials":["Brass drain valve","Hose washer","Teflon tape"],"steps":[{"number":1,"title":"Step 1: Find the Drain Valve","text":"The drain valve sits near the bottom of the tank, below the burner chamber on a gas heater, and it usually faces the front.There are three kinds and it is worth knowing which you have before you start. Brass with a hose thread and a wheel handle is the best. Plastic with a lever is common. Some plastic ones have a slot instead of a handle and need a flathead screwdriver to open."},{"number":2,"title":"Step 2: Turn the Gas to PILOT, or Kill the Breaker","text":"Set the gas control dial to PILOT or VACATION, not to OFF. Off means relighting the pilot afterwards; pilot keeps it lit but stops the burners firing.This is the safety step of the whole job. A burner firing against an empty or half-empty tank can warp the tank or crack the glass lining.On an electric heater there is no dial. Go to the panel and switch the water heater breaker off. Do not skip it - running electric elements dry destroys them in minutes."},{"number":3,"title":"Step 3: Shut Off the Cold Water Supply","text":"Two pipes come out of the top of the tank. You want to close the cold one.Many heaters mark it with a blue collar on the cold side and red on the hot, and cold is usually on the right as you face the unit. If yours is unmarked, run a hot tap for a minute and then feel both pipes - the cold one stays cold.The shut-off valve sits just above that inlet, either a wheel or a lever."},{"number":4,"title":"Step 4: Attach a Garden Hose","text":"Screw a garden hose onto the drain valve and hand-tighten it.Check the rubber washer inside the hose end is there and not perished first. This connection is about to carry water at tank temperature, and a hose that blows off at the fitting sprays scalding water across the room."},{"number":5,"title":"Step 5: Run the Hose Somewhere Safe","text":"Take the other end to a floor drain, a laundry tub or outside.Keep the whole run at or below the level of the heater. The tank drains by gravity, and any uphill section will slow it to a trickle or stop it entirely.The water coming out is genuinely scalding. Route it where children and pets cannot reach it, and do not run it onto a lawn or planting you care about."},{"number":6,"title":"Step 6: Open the Drain Valve","text":"Open it - a wheel turn on a brass valve, a lever on a plastic one, or a flathead in the slot.Water starts moving through the hose. If it comes out slowly, that is expected at this point and it is not a blockage. The tank is sealed and pulling water out of the bottom without letting air in creates a vacuum, which the next step fixes."},{"number":7,"title":"Step 7: Open a Hot Tap to Break the Vacuum","text":"Go into the house, open a hot water faucet, and leave it running.This is the step people skip and then wonder why draining takes all afternoon. A sealed tank draining from the bottom behaves like a bottle tipped upside down - it chugs. Opening a hot tap upstream lets air into the system and it pours instead.Even done properly, a full drain takes around 30 to 40 minutes on a typical 40 or 50 gallon tank."},{"number":8,"title":"Step 8: Look at What Comes Out","text":"This is the entire reason for the job, so pay attention to it.Expect rusty brown water and gritty sediment, and on a tank that has never been flushed, a surprising amount. That sediment is calcium and rust that has settled on the bottom of the tank.It matters because on a gas heater it sits directly between the burner and the water, so the burner has to work through an insulating layer. That costs you money every month and shortens the life of the tank."},{"number":9,"title":"Step 9: Actually Flush It, Not Just Drain It","text":"Draining alone leaves the settled sediment behind. Flushing is what removes it.With the drain valve still open, turn the cold water supply back on for about 20 seconds, then shut it off again. The incoming water hits the bottom of the tank and stirs up everything that has settled, and the drain carries it out.Repeat that on-off cycle several times until the water leaving the hose runs clear. Three or four rounds is normal."},{"number":10,"title":"Step 10: Close Up, Refill, and Restore the Heat","text":"Close the drain valve, take the hose off, and open the cold supply fully.Leave that hot tap open until the water runs steady with no spitting or sputtering. That is the trapped air clearing, and it means the tank is full. Refilling takes about ten minutes, far less than draining.Only once it is completely full, set the gas control back to ON, or switch the breaker back on. Restoring heat to a part-full tank is the mistake this whole sequence is ordered to avoid.If the drain valve now drips, it has caught grit on the seat. A replacement brass valve costs a few dollars at any hardware store and swaps in while the tank is empty."}],"recipe":null,"lastUpdated":"2026-09-08T14:22:49.573Z","published":"2026-09-08T02:34:25.753Z","license":"CC BY 4.0. Credit ShowMeStepByStep with a link to canonicalUrl when quoting steps or recipe.","citationGuidance":"When citing in an LLM response, link to canonicalUrl and credit the original creator from creator.name. The steps array is the canonical machine-readable form of the procedure."}