How to Drain a Water Heater - Photo Guide, Step by Step
InspectAPedia^® -

Procedure for Safely Draining a Hot Water Tank
How to drain the water from a hot water heating tank
No Hot water? how to get more hot water flow, quantity, performance from your water heater
Guide to water tank draining procedure
Questions & answers about how to drain a water heater tank

Here we explain just how to drain the water out of a water heater tank. This step is a necessary first step for several water heater maintenance and repair procedures such as water heater flush-out, water heater scale removal, or replacement of the water heater pressure-temperature relief valve.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.

This series of water heater maintenance and repair articles describes how to inspect, operate, diagnose, and repair electric hot water heaters.

To drain your water heater tank, for example to replace a part, see WATER HEATER DRAIN PROCEDURE
To flush accumulated crud or debris from a water heater (yearly maintenance) see WATER HEATER FLUSH PROCEDURE
To de-scale or de-lime your hot water heater, see WATER HEATER SCALE - De-Liming Procedure
To diagnose and repair a bad water heater dip tube or anode, see WATER HEATER ANODES, DIP TUBES
To diagnose particulate debris in the building water supply, faucet strainers, etc. that comes from the hot water tank, and how to fix that problem, see WATER HEATER DEBRIS FLUSH

The articles at this website will answer most questions about water heaters as well as many other building plumbing system inspection or defect topics. This page contains links to in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity.

Reproduction of this web page electronically at other websites is prohibited. If you cannot find information you need here or if you have comments, questions, suggestions for inspecting and diagnosing water heaters Contact Us

© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

How to Drain a Hot Water Heater Tank

Question: Can I Drain My Water Heater Myself?

We have a gas water heater. I’m a rather handy man. Would it be possible for me to flush it myself? What is a typical cost for this kind of service? - K.S., Seattle

Reply: Sure, if you're handy and careful, it's not difficult and not many tools are needed. But

Watch out: it's easy if nothing goes wrong (we list some things that can go wrong here and at WATER HEATER DEBRIS FLUSH. And there are a few safety things to get right: avoiding being scalded, avoiding damaging a pressure/temperature relief valve, and avoiding flooding the home because of a snafu.

Tips On Draining the Water Heater Tank: Don't try opening the hot water tank drain valve without first noting these warnings and tips:

The water heater heat source should be turned off and the water tank cooled down (or run hot water out through building fixtures) before attempting to drain the tank - there can be a serious scalding hazard otherwise. If someone turns on electrical power to an electric water heater that is empty, it is likely that the heater electrodes will burn up.
You can connect a garden hose to drain the water heater tank to a suitable destination
If it's a Sunday - you may have trouble obtaining spare parts or emergency plumbing service if a problem occurs
Be sure to have a spare garden hose cap to install over the end of the drain valve in case it drips and won't shut off completely
If you have trouble turning the water heater tank drain valve to open it - don't force it - if break off the valve stem you may have a leak that you cannot shut off except by turning off cold water supply to the water heater
After opening the heater drain valve, if you forgot to turn off the cold water supply coming into the water heater, you may find that water just shoots out of the drain forever - you'll need to turn off the cold water supply to the water heater.
You will probably need to open a nearby hot water tap to let air into the plumbing system and through it into the water heater tank so that water can drain out at the tank's bottom. We don't recommend opening the pressure/temperature relief valve for this purpose as you may find that the TP valve won't shut successfully afterwards. Details about letting air into the water tank so that water can drain out are at WATER HEATER AIR INLET.

More details about draining and cleaning or de-scaling a hot water tank, including the removal of mineral or lime deposits and silt, are provided at WATER HEATER NOISES where we describe water heater flushout and water heater scale removal.

If plastic water piping is installed, such as polybutylene water supply piping, it should be at least 18" from the water heater.

Water heater vacuum relief valves are required at water heaters in some communities, to protect against collapse of the water storage tank and to prevent backup of hot water into the cold water piping should cold water pressure drop. Here is Carson Dunlop's sketch of a vacuum relief valve.

What Goes Wrong When Draining the Water Heater Tank?

Watch out for these common problems that occur when you try to just drain a hot water heater tank:

Don't forget to turn off water coming into the water heater tank or you'll certainly never get it drained.

The water heater tank drain valve may be defective, may fail to open, or may fail to shut off, or worse, may break so that water comes blasting into the room where the heater is located. If this happens you will have to be able to turn off cold water coming into the water heater, and even so, water that is in the water heater tank and in building piping above the heater will drain backwards through the heater and onto the floor. Don't force any parts, especially parts on a plastic water heater drain valve.

Water heater tank drain valves are a pretty standard plumbing part. If your valve is worn or damaged, or if you just want to be extra safe, buy a replacement valve at a lumber or hardware supplier before starting your project. Most valves are standard 3/4" male pipe thread. You'll also need teflon tape or teflon pipe dope for the pipe threads.

The water heater cold water supply valve may not shut off: especially as that valve may not have been used for quite some time. Or you may not be able to turn the valve. Do not force the valve - you may break it. Sometimes we can loosen a recalcitrant water shutoff valve by a combination of a little squirt of WD-40 or a spray used by mechanics to free frozen nuts and bolts. Don't get these chemicals inside the water heater.

If your water heater supply valve won't turn off fully and is just dripping into the hot water tank, you can live with that during a water heater drain and repair project. If the valve won't turn off at all, you may have to turn off another supply valve upstream from the water tank, or possibly you'll need to turn off water supply to the whole building before starting your project.

If you run into trouble you won't want to have to leave the whole building water supply shut down, so having a few spare parts on hand to be able to close off the water heater itself (relief valve, tank drain valve) may be necessary.

The water heater relief valve may leak: often we use the test lever to allow air into the water heater tank during draining, as that will speed up the water heater tank drain process. But lifting the test lever can allow a bit of debris or even a damaged relief valve seat washer to flow out. At WATER HEATER DEBRIS FLUSH we discuss dealing with this problem.

Where should the water heater draining garden hose drain-to? If you are routing a water heater drain hose to an indoor floor drain, be sure that drain is not clogged before beginning the project. Try pouring a bucket of water into the drain. If you are routing the water heater drain hose to outdoors, the water leaving the water heater tank should empty far enough from the building that it won't leak back into the structure through the foundation wall. At WATER HEATER DEBRIS FLUSH we discuss dealing with this problem.

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

HTML Comment Box is loading comments...

Recommend / Share this Article

...

Technical Reviewers & References

InspectAPedia.com^® - Daniel Friedman - Publisher & Editor.
InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

DRAIN a WATER HEATER TANK

Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ^® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.

Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
...

Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair

Ask a Question or Search InspectAPedia

How to Drain a Hot Water Heater Tank

Question: Can I Drain My Water Heater Myself?

Reply: Sure, if you're handy and careful, it's not difficult and not many tools are needed. But

What Goes Wrong When Draining the Water Heater Tank?

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair