Almost all water heaters have been made the same way for the past 60 years. They construct a steel tank, then bond vitreous glass to the inside of it to keep it from rusting. There are variations in manufacturing quality, however, so some tanks might have a better glass lining than others. And there is always a small amount of steel exposed, due to limitations in the coating process. To protect that steel, the makers install sacrificial anode rods in the tanks. Click the link for details -- after you've finished reading here. Suffice to say that when your anode is all gone, the tank will start to rust out -- unless you put a new anode in. However, your tank could also rust externally and fail. It has lots of rust protection inside, very little outside, so watch out for leaks. You can see a little of the anode of this old tank, hanging down on the right. In fact, take a long look at it. There is the white-and-blue shell, the actual tank within it, a flue running down the center, a drain valve (bottom left), a fancy draft diverter, also known as draft hood, on top, with the hot-water outlet visible in front of it. If you had X-ray vision, you could look through the floor and see the gas burner that heats the water and the opening for that flue. It would take more than X-ray vision to see the dip tube because it fell apart long ago. On newer heaters, though, you would see it as a plastic tube hung underneath the cold-water inlet and extending about two-thirds of the way to the bottom. It brings cold water into the tank to the bottom to be heated. Check out our Safety and Hazards information, as well as our Water Heater - Frequently Asked Questions.

Inspection and Maintenance
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. 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 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. 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 caution!
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.

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

Gas Heaters
You should open the combustion chamber and have a look 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. 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, like the one below. (This one was a goner.)

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. 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.

Electric Heaters

These are 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!

Maintenance

The Anode
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 gate 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 gate valve is stripped 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. I'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.

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 sometimes under a sheet metal top that's foamed into place. In these cases, one must drill through the sheet metal (not too far) and then use a screwdriver to feel around and find the hex head. 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. 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. 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. 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 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. There is another possibility, however, that may "save face." An impact wrench, which resembles a drill, also works. Those cost as little as $50, but you may also be able to rent one for less. Or you might just hire a plumber who has one and let him do all this stuff. But the tool requires finesse. You want to use it to break loose the anode, but not let the hex nut spin or what's left of the anode will break off and fall into the tank. We suggest you use the impact wrench to merely loosen the hex nut, then use a regular socket wrench to take it out and tighten the new one. 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. If things are really tight, you may have to use a segmented anode, which has been milled down to the core wire, which is soft. That allows the segments to be bent, inserted in the tank, and straightened out. The catch is they cost more, and the core wire can snap after a couple of bends-straightens. 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, 2007: This isn't nearly really as true of the .84-inch anodes we're now selling as it was the .75-inch rods we used to sell.) 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 flex rod. 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 current flowing between the anode and the tank, 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. If you're installing a combo anode in a Rheem/Ruud/Richmond/GE tank 2005 or newer, better get the special combo rod for that. Standard ones might not work. They redesigned and created a deeper hot port that may block the hot-water outlet on a standard anode.

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. If you have poor water pressure, however, this may not work. 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. 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. There are a couple of types of valves. For the "cone" type, which is straight, you open it by making three or 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 looks like a little spigot. It is one piece and is screwed right into the tank and it has to come out. 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 plastic-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. Finish with the handle pointing down so that nobody comes along and snags it and floods your apartment. Those with children might want to invest in a small brass or zinc cap that screws onto the end of the hose adapter. 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
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 a standard tank, it's straight, which means the water comes in, hits the bottom, and scatters sediment in all directions, so that it settles evenly. 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. 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.