Water Heater Rescue: Know-How, Troubleshooting, Anodes graphic

Water Heater Maintenance > Know-How: A
Hands-On Guide to Preventive Maintenance

What you'll find on this page: you'll learn how to do an external inspection of your heater if you wonder what kind of shape it's in and whether you want to do more, or just buy a new one. It also walks you through what's involved in changing an anode or swapping out a drain valve and dip tube.

This is where you can find out what's involved if you want to check the condition of your water heater and possibly retrofit it for longevity. You can also use this page to prefit a new water heater.

We think the keys to that are having a tank with an easily accessible, functioning anode rod, little or no sediment, and a functioning temperature/pressure relief valve. It should be firmly strapped against earthquakes, if that's an issue, and 18 inches off the floor where it won't ignite fumes. (Water heaters built to the FVIR standard of 2004 might not require being raised; check your codes)

If it's inside, it's sitting on a drain pan so that if anything does leak, it won't flood your living room, or perhaps your garage -- and the pan has a drain line that goes somewhere safe. It's plumbed with plastic-lined nipples, and copper flex lines on both nipples and the T&P valve. The plumbing around it is in good shape, and water isn't dripping onto it from overhead plumbing.

But First a Caveat:

Electricity is dangerous. Gas can be dangerous. Water pressure, if not dangerous, can cause household disasters.

There is considerable information below on how to work on your water heater, however, you are responsible for how you use it. If you have the slightest doubt of your ability, get a professional. People grump about what plumbers charge, but what you're paying for is a truckload of specialized tools and someone with the expertise to use them if things don't go right. That often happens with plumbing. When it does, the plumber's fee becomes a bargain. And that said, people have occasionally encountered plumbers who say, "It can't be done," or "It shouldn't be done." Not all of them have heard of water heater maintenance. Have them contact us if that happens.


The first thing to do is figure out the age and condition of the tank. Most people buy them and forget about them until it's time for another.

A water heater label often can tell when the tank was made

So, look on the label. The first four digits of the serial number often contain a date of manufacture. It can take the form of month and year or week and year. The month may be indicated by a number or a letter. 01 or "A" for January, 02 or "B" for February.

Thus, B95 means February 1995; 9516 means the 16th week of 1995. On the label at left, the serial number shows the tank was made in the first month of 1997 (the 0197 leading digits). If it's more than six years old, you should check its condition.

Bradford Whites and some Americans have a letter/number code you can't read without the codebook. But there will be an American National Standards Institute (ANSI) year mark somewhere and it will be no older than that.

For Gas Heaters...

Inner combustion chamber hatch
Outer combustion chamber hatch

... you should open the combustion chamber, if you can, and have a gander inside.

First, turn the control to pilot. That way, you don't get your face singed. Then remove the outer hatch -- with gloves or pliers, if the tank has been firing. Then do the same with the inner cover, if it's an older heater. If it was made since 2004, you may only be able to peer as best you can through a small window. The combustion chamber is sealed as part of a safety system and there is no removable inner hatch.

What and where are the hatches? At the base of the heater, perhaps below the control, as here. This outer hatch, top photo, has two tabs that fit in two slots at the top. Others we've seen have the slots and tabs at the side. The inner hatch, far right, merely sits in the opening to the combustion chamber.


Good combustion chamber roof

Shine a flashlight inside, onto the roof of the chamber. What does it look like? If the tank is sound, there shouldn't be much to see, except maybe some white marks from condensation.

If, however, the tank is headed for ruin, there will be signs of heavy rusting and pitting around the flue, rust flakes on and around the burner, and marks of water having run down the sides.

If you find these marks, begin shopping for a new tank, because yours probably doesn't have much life left. And don't forget to prefit the new one so you don't have to do this again.

Bad combustion chamber roof

The first picture, top right, is from our own water heater, now 37 years old after being maintained as we advocate here. It is not a perfect tank bottom; we've seen better. But it's a very good one. This heater may yet weep at our funeral. As to the second one, it wasn't so good. We wept at ITS funeral!

When you've finished your inspection, replace the hatches and BE SURE TO TURN THE CONTROL BACK TO ON. Otherwise, you or someone else will eventually be in for a cold shower.

For Electric Heaters...

Upper electric element port
Top of electric water heater

... it's not quite as straightforward. There isn't a combustion chamber. But you can turn the power off and inspect all the fittings and open the element ports, left, and the port for the power cord on top of the tank, right. Look for signs of leakage and longtime corrosion.

Make sure the power is really off!

And when you're done, put everything back together the way you found it. It can affect the operation of the heater. Don't forget to turn the power back on or you'll have a cheap thrill the next time you take a shower!




The Anode

OK. The combustion chamber is sound, or the ports look OK. What next? Time to pull the anode, which will tell you how much life your tank has.

  1. Close the cold-water valve.
  2. Turn the control to "pilot" on gas heaters or shut off the power to electric ones.
  3. Remove the vent pipe, if there is one, to allow working room.
  4. Open a hot-water faucet somewhere in the dwelling to relieve pressure.
  5. Let a gallon or so of water out the drain valve, if you can. If the hot water doesn't stop running when you open a faucet, that means your valve is toast and the water is NOT shut off. If this happens, shut off the water at the main. Otherwise, when you unscrew the anode, it will launch like a rocket. We've had this happen. It's exciting. If you have a two-story house, or the water heater is in the basement, water can still drain down from the upper piping and bubble out the anode port when you open it. If this is the case, consider attaching a hose to the drain valve and opening the latter somewhat to keep the water level in the tank from rising to the level of the anode port. If nothing comes out the drain valve, sediment may be clogging it. Opening the temperature/pressure relief valve may help let out some water. Or you may want to skip to the section below on replacing the drain valve and then come back.


A hex anode is exposed on top of a water heater, right, and recessed, left

Now the fun begins. On some tanks, the hex head of the anode is exposed and in sight, such as in this picture. On others, it's hidden under a plastic cap. There are usually several of those anyway where the foam insulation has been blown in. But the anode cap will be halfway in from the edge. And on a few, the anode may be under a sheetmetal top that's foamed into place.

Anodes under the sheetmetal are very rare now, but if you have that, you must drill through the sheetmetal (not too far) and then use a screwdriver to feel around and find the hex head. Don't try to unscrew the cover. The foam holds it, too.


The anode will most likely be on the back side of the tank, 1 1/2 inches out from the flue in a semicircle between the hot and cold ports.

Once it's found, drill another hole and use it as a start for cutting a hole with tin snips to give access to the anode. Be sure to tape the sharp edges or pound them down with a hammer.

combo anode

Another possibility, as on some A.O. Smith and Bradford White tanks, is that there is no hex-head anode, just a combination nipple/anode/hot water outlet, such as the one on the right. You can determine this by disconnecting the hot-water-side flex connector, and running a long screwdriver or similar implement down the nipple. If it stops after a couple of inches, it has run into the combo rod. Or you may have heat-trap nipples that prevent that so that you'll have to remove the nipple itself to determine if it is part anode. In most cases, it will not be any picnic to get the anode loose. Original anodes are not installed with pipe thread seal tape. That means they're in TIGHT.


A note about Bradford White combo anodes: BW uses an exceptionally short pipe nipple, likely for packaging purposes. It's only about two inches long, as opposed to the 4-inch nipples we sell. What that means is two things: one is that to remove one for inspection, you just about have to wreck the threads because there is no smooth place, as in the picture at right, to put the wrench. The other is that if you replace one later with a combo with a longer nipple, you'll have to adjust the plumbing. That might be easy if you have flex lines, or hard if you have soldered copper. Water heater socket size is an industry-standard 1 and 1/16 inches.


Anyway, if, (A) you're a person of great strength, and (B) have a couple more like yourself to hold the tank steady, take a 1 and 1/16-inch socket wrench and a cheater bar to put on the end of it to give maximum leverage, and GENTLY loosen the anode. I say "gently" because if you don't, when it gives, you may fly, face first, into the wall, or at least, bloody your knuckles.

Anyway, there may be a further difficulty in changing the anode: overhead space. Getting the old one out won't be hard, since if there is little hard metal left on it, you can just bend it. Getting the new one in may be the hard part. The rods are 44 inches long for hex anodes and 48 for combos.

You may have to use a segmented, loose-link anode, which has sections connected by wire. You can feed the sections in one at a time. The catch is they cost more. But they're good down to 12 inches of clearance.

However, there are also a couple of tricks we use. One is to run the anode up the vent pipe, if it is a straight path out, then back down into the tank.


Another is to bend the new rod over your knee (or some other stiff object if you have soft knees). Even a magnesium rod will bend quite a lot. (Editor's note: This isn't nearly as true of the .84-inch and .90-inch magnesium anodes we're now selling as it was the .75-inch rods we used to sell, but will still work for aluminum/zinc.) Then when you put it in the tank, you can brace it against the opening to bend it back. When you think it is straight, touch the lower end to the tank side and turn the rod. If it is not pretty straight, it will wobble and you may have a hard time tightening it down. This fix is good down to 30 inches of clearance. Again, though, if you have doubts about this, buy the flexible anode.

Still a third way is, if you know there's dead space above the ceiling, you can drill a hole through the sheetrock and run the rod up through it and then slide it into the tank.


Anyway, when you take out the old anode, inspect it. If more than six inches of core wire is exposed, or the anode is splitting, replace it. In either case, put the new one in with pipe thread seal tape. That way, the next time, a great deal less work will be involved. How often to check back depends on what you find. If it looks like there's a lot of metal left, and you don't soften your water, three or four years is reasonable.

(People occasionally ask us if pipe-seal tape applied to the threads of the anode blocks the electrolytical reaction. Tanks we've serviced repeatedly usually have corroded anodes. We've tested with a multimeter and found electrical continuity, despite the tape.)

There's an alternative, however. You can leave the old anode where it is, and install a combo rod on the hot side. You won't learn the condition of the old anode, but you won't kill yourself, either. All that's involved is disconnecting the hot-side plumbing, removing the old nipple with a pipe wrench, and putting in the new rod (with pipe thread seal tape!). Check it again in about four years.

One more thing: if the anode looks perfectly whole and it's been in the tank for a long time, replace it anyway because it has passivated and can't be counted on to do its job.

The Sediment

What about the sediment? You'll want to put in a curved dip tube and new drain assembly. You can either try this yourself, or have a plumber do it, using the instructions from this site. The parts are available from us. Look in Products.

If you have poor water pressure, however, this may not work. If pressure is a problem, see Quick for a possible solution. Otherwise.......

First, replace the drain valve, which is typically a cheap, 3/4-inch plastic affair that easily clogs with sediment and may not stop dripping when you close it. Even if it's brass, as on some of the higher-end models, it will still be prone to clogging unless it's a ball valve, but at least you won't have to worry about it breaking off when you try to remove it. Don't even think about draining the tank. That takes forever, and is not necessary. DO be sure the water pressure is off!


For this operation, you should be prepared for a little water coming out. Put down a plastic sheet, then perhaps a towel or two. Have a rag nearby, something that won't disintegrate (NEVER use sponges), as well as a bucket and a small basin. Also have ready a flat-bladed screwdriver and a hammer.

Cone and spigot plastic drain valves

There are a couple of types of valves. For the "cone" type, (right top) which is straight, you open it by making about four turns counterclockwise and kind of pulling on it. Then you turn it two or three turns clockwise and it comes off. However, before you take it all the way off, you can tape the end of the old nipple, if it's metal, with pipe thread seal tape. Then you can put the new drain assembly on it, just as you remove the old.

The other kind of valve (right bottom) looks like a little spigot. It is one piece and is screwed right into the tank and it has to be removed completely.


The best way of proceeding with this type is to use a basin wrench and a crescent wrench. The basin wrench is a square tube of metal with a little pair of jaws at one end. To see an example, check the Tools section. You clamp the jaws on the neck of the valve, as close to the tank as possible. Then you turn it with the other wrench. This offers the best chance of getting the valve out without breaking it.

But don't be surprised if it does break. What now? Now the rag. Stuff it in the hole and stop the water. Then take the screwdriver and using the hammer, tap out the rest of the neck of the valve from the port. Quickly install the new drain assembly, which in this case will consist of a PEX-lined nipple, brass ball valve and hose adapter, all taped with pipe thread seal tape, and all already assembled. Make sure the valve handle is parallel to the valve body and pointing away from the tank. That will ensure that you don't accidentally put the valve on backward.


You can leave the valve open for a moment (this is the reason for the basin or bowl) to decrease resistance while you start it in the threads. Once that's done, however, close it. Putting the pliers on the hose adapter will tighten the whole assembly, one piece after the other. Finish with the handle pointing down so that nobody comes along and snags it and floods your dwelling. Those with children might want to invest in a small brass or zinc cap that screws onto the end of the hose adapter. (That is included in our Sediment Flush Kit and Ball-Valve Drain Assembly).

Now, this sounds like a lot of work, but it only takes a few minutes. A tank already in service can be retrofitted in 40 minutes -- without draining it. A new one can be prefitted in 20 minutes.

The Dip Tube

straight and curved dip tubes

The other part of retrofitting is replacing the dip tube. That is the cold-water inlet tube, which introduces cold water into the bottom of the tank, so it doesn't mix with the hot water at the top.

In many standard tanks, it's straight, which means the water comes in, hits the bottom, and scatters sediment in all directions, so that it settles evenly. Others may have a "self-flushing" dip tube that is curved, but closed at the end. We don't think they do anything much.

If you replace this with a curved dip tube, with the curve pointed opposite the drain valve, the sediment will swirl around and out when you flush. Examples of both can be seen above. The straight one merely is flared at the top to sit on a ring in the port. Curved dip tubes have an integral plastic-lined steel nipple, which doesn't show in the photo.

So. To work. Disconnect the cold plumbing from the tank. Using a pipe wrench, remove the nipple. Using a dowel and a circular motion, work the old dip tube up where you can grab it and pull it out.


Sometimes the factory-installed dip tube rests on a steel ring that won't permit passage to the curved dip tube. Drilling it out with a 7/8-inch hole saw takes about 30 seconds.

After that, screw in the dip tube with the mark inside the nipple indicating the direction of the curve facing away from the drain but not toward the flue, if there is one. It should be aimed at the wall of the tank.

rust-clogged pipe nipples

Hook up the cold plumbing to the nipple, reconnect the vent pipe if the heater is gas, and open the cold-water line. When water comes out the open tap and stops spurting, you can close the tap. Turn the control back to ON for gas, or turn on the power for electric heaters..

Now to get rid of sediment, you just flush the tank by hooking up a hose and opening the ball valve, with the water pressure on. Do this twice a year for about five minutes.

These procedures apply equally to gas-fired and electric tanks.

Plastic-lined steel pipe nipple

To look for signs of impending failure on an electric tank, check the heating-element ports for signs of rust and leaking.

And keep the temperature at about 130 degrees in all water heaters. Legionella bacteria have been discovered in sediment at the bottom of many electric tanks set at lower temperatures. It is thought that the higher temperature kills legionella.

Some of these parts are hard to find, so we sell them. See Products. Full retrofit kits and single components are available. Combo anodes and dip tubes have integral plastic-lined steel nipples such as the one in the lower-left picture. Its plastic insert prevents what you see in the righthand picture, galvanized nipples after years of service, clogged with rust. They don't have heat-trap nipples. Those have caused a lot of grief in the past. We prefer making heat traps out of plumbing and insulating those.

Getting It Done Without Doing It Yourself

If you're reading this, then we've convinced you that servicing your water heater is worthwhile. But you might not be capable of doing it yourself. A reasonable question now would be, "What do I do?" And there are answers.

You can buy parts from Water Heater Rescue, which come with instructions, naturally, and hire a plumber to retrofit your heater. Even if he doesn't know anything about water heater servicing, any plumber can do this work, following these directions. If he/she has questions or qualms, e-mail us and we'll answer them.

Remember, though, that we have encountered plumbers who know nothing about service, but know that they can make quite a lot of money by convincing you to let them replace your water heater. Some will automatically say, "Ten years old, needs replacing." Knowledge is power. By informing yourself here, you can deal knowledgeably with anyone, and get what you want, not what they want.