W.M., Milton

A. The milky look to the hot water is due to thousands of little air bubbles in the water, created when the water is heated. There is nothing wrong, and those air bubbles are harmless. Why they are occurring now and not in the past is a question the Handyman does not have an answer to. Here's one thing you can do to test my theory: Fill a tall glass with hot water, and let it stand for a few minutes. You will see the water become clear.

Q. The hot water from my bathtub faucet produces very little pressure, while the cold water is OK. The pressure is OK with both hot and cold water on all other faucets in the house. What's wrong and how can I fix it?

SUZANNE FURIGA, Brookline

A. There is something defective with the hot water valve. If it is a one-handle faucet, shut off the water, take out the cartridge and take it to a plumbing supply shop for replacing. If it is a two-valve faucet (two tap handles), remove the cartridge of the hot-water faucet and buy a replacement. In the latter cases, sometimes a cold-water cartridge is mistakenly installed in the hot water valve.

Q. What's the best way to insulate a hot-water heater?

M.A., Ashby, Mass.

A. Modern hot-water heaters are already pretty well insulated but you can always add more.

You cannot overinsulate a hot-water heater, although you might reach a point of no return; that is, the cost of the insulation will be more than the cost of hot water saved. It is still a good idea, particularly if the basement is cold.

Wrap the heater with 3 1/2-inch-thick fiberglass batts or rolls, with the paper backing showing. Tape all joints with duct tape. You can leave an opening for the control panel, cutting the insulation to fit into the opening.

Do not cover the pressure-relief valve. And with a gas heater, do not cover the burner or air intake for the burner and do not cover the chimney at the top.

Q. How important is it to remove sediment from the bottom of a hot water heater by draining off a few quarts regularly? I read so often that it should be done to lengthen the life of the heater.

D.E., Hingham

A. There are a lot of things we are supposed to do about our houses, but if we don't, there is usually no harm done. I really don't think draining off a few quarts of water every now and then is going to make a big difference in anything. The sediment is in the water, the same stuff that we collect in our faucet filters. When it falls to the bottom of the tank, it is likely to stay there, causing no harm. On the other hand, draining water every so often certainly wouldn't hurt anything.

We are also told to open the pressure-relief valve on the top of the heater every so often to make sure it is working, and what is does is relieve the pressure of water in an overheated tank. This is a good idea, because if the valve fails and the tank overheats, it could explode, or at least break up, spilling water all over the basement floor. The only problem: People have done this, then discover they cannot get it to work again, so they have to replace the valve.

Q. I have a problem with my hot water. It is turning everything brown. My husband drained the tank and produced no rusty water. A related problem is a funny odor from the bathroom sink and tub. Are there any quick or easy cures for these problems?

A.W., Framingham

A. There may be cures, but none is quick or easy. The water that turns everything brown may have a high iron content, not enough to cause rusty water but enough to cause those brown stains. The cure there is to put an iron filter on the water intake. If you have one, it should be cleaned, and possibly replaced, regularly.

Another cause of the stains -- and the funny odor -- maybe a high concentration of hydrogen sulfide in the water, caused by bacteria. If so, you can have the water tested, then take appropriate steps. Check for any filters and replace them. Often enough, a dirty and neglected filter (they need cleaning and/or replacing regularly) is the cause.

Finally, in most water heaters is a long magnesium bar known as an anode rod. This sacrificial metal piece protects the tank from rust by corroding before the tank does. Once the rod deteriorates, the tank will too, causing stains and rusty water. You might be able to solve the problem by replacing the anode rod, which deteriorates in about four years. Replacing the rod can double the life of your tank. It is best to have a plumber replace this rod.

One more thing: This has to do with the odor from the bathroom fixtures, and is a common occurrence. Oil, grease, hair, and other odoriferous things often build up inside the drain, narrowing it and smelling to high heaven. The cure is to remove this buildup, with a plumber's snake or by simply pouring a cup of bleach into the drain and leaving it overnight. Repeat as often as necessary.

Q. My hot water heater is producing brown water after about 8 years. The warranty is 5 years. My husband drained it without success. Is there anything I can do to extend its life?

NANCY TRIMPER, Wakefield

A. There is nothing you can do about extending the heater's life because it's dead. Somehow, water has rusted metal parts, and the rust is getting into the water. The ony cure is replacement. It's too bad about that 5-year warranty, but it's a fact of life. Heaters usually go, it seems, just a few months after the warranty expires. Maybe you can do better with a heater that has a 10-year warranty.

Q. I have a two-zone hot water system in my 35-year-old house. It works OK, but I hear sloshing of water in the expansion tank. The tank has a diaphragm. Is there a way I can stop that sloshing.

L. L., Newton

A. Yes. You can recharge the tank. Since it is a diaphragm tank, add air to the tank with a bicycle pump. If the tank is a conventional one, it is recharged by draining it. This is done by closing the shutoff valve between tank and boiler and opening the discharge valve to drain the water into buckets or into a sink or floor drain. When the tank is drained, close the combination valve and open the shutoff valve to refill the tank to its proper level. If neither of these treatments works, call your service man.

Q. I heat with hot water, with a tankless hot water heater in the boiler. It is 7 to 10 years old, but I was told the built-in tank is about to go. A replacement would cost $800. A friend suggested getting an electric hot water heater separate from the boiler. Is this feasible?

B.Mc., Burlington

A. Who's your friend, the president of the electric company? He'll be glad to take your money, and a lot of it, to heat water by electricity. Some people can't help doing that for many reasons, but you don't have to use this most expensive (by far) way to heat water.

Stick to the tankless; if it is providing enough hot water for your needs, it ain't broke, so doesn't need fixing. And, it should last longer than 7 to 10 years. If it is not producing enough water for your needs, have it treated to make it work again. Or, replace it. The cost estimate is just about right.

Q. I had an electric hot-water heater installed in December in my condo. I don't use it too often (I use another one regularly) and once when I filled the tub, rust and sediment came straight out of the hot-water tap. I called the installer, who flushed it and it is fine. How can I keep the heater going and prevent that rust and sediment buildup?

M.M., Melrose, Mass.

A. Get in the habit of draining off a gallon or so of water once a month. This will not only prevent buildup of rust and sediment, but it will also stir up and remove the sediment; if sediment is left to pile up, it acts as an insulator, which can cause the heater to burn out before its time.

Q. What's the best way to insulate a hot-water heater?

M.A., Asbhy

A. Modern hot-water heaters are already pretty well insulated but you can always add more. You cannot overinsulate a hot-water heater, although you might reach a point of no return; that is, the cost of the insulation will be more than the cost of hot water saved. It is still a good idea, particularly if the basement is cold.

Wrap the heater with 3 1/2-inch-thick fiberglass batts or rolls, with the paper backing showing. Tape all joints with duct tape. You can leave an opening for the control panel, cutting the insulation to fit into the opening. Do not cover the pressure-relief valve. And with a gas heater, do not cover the burner or air intake for the burner and do not cover the chimney at the top.