When a hot water tap was turned on (after not having been used for, say, 10 hours), dirty water came out. After running for a few second, the hot water became 'clear' but with a tinted color. The hot water remained 'clear' for the rest of the day. The next day when a hot water tap was turned on, the same thing happened again. Incidentally, the cold water has always been clear.

The plumber advised that the hot water tank was rusty and replaced it with a new one. After installation and when a hot water tap was turned on, dirty water (worse than before) came out and turned clear after a few second. The plumber said it's normal. The hot water appeared to be clear for a couple of days. Then the dirty water returned but with a lighter color. Again, after running for a few second, the hot water became 'clear' but also with a tinted color.

My understanding is there are no galvanized pipes; all pipes are copper. Could someone please help? Thank you.

You may have iron in the water heater. Flush the water heater from bottom of tank at spigot. Do NOT turn water off, flush from bottom for about ten minutes let sit for 1 hr and repeat.
RJ

Thank you RJ. I'll do that and report back.

Hi RJ, I attempted to flush the water heater as suggested but abandoned the operation after a minute or so. I was not sure whether I am doing it correctly.

I took the lever of the relief valve towards myself at about 30 degrees and hot water came out slowly through the relief drain pipe. After less than a minute, there was a rumbling noise. The lever appeared to tremble and the water 'rambling' out from the relief drain pipe. I released the lever at this point. After about 15 minutes, went back to do it again and the same thing happened.

As can be seen from the diagrams, the relief valve is at the top half of the hot water system. What do you mean by 'flush from bottom'? Did I do it correctly? The rumbling noise was alarming. Is it possible to lock the lever in position so that I don't have to hang on to it for the whole 10 minute duration? The lever does not look robust. I am afraid I might break it by lifting it at more than 30 degrees.

A couple of things I neglected to mention in my original posting: (1) The old hot water system (1-year old) was drained before a decision was made to have it replaced. (2) The premises was used as an office for over two years. The hot water was hardly used. Would that have an effect on the pipes?

Since posting my request for help, I have collected some hot water from two of my neighbors. One hot water system (same brand as mine) was installed three days before mine; the other is a different brand and is at least two years old. Both have clear hot water.

Thanks.

That is not how you flush a water heater plus you might now have to replace that T&P valve if it won't reseal 100%. Open the spigot at the bottom of the heater and direct the water via a hose to waste. I still think you have some old galvanized pipes somewhere in your hot line.

If old galvanized pipes do exist, what would be involved in having them replaced? Thanks.

Usually not a DIY project so call 3 plumbers for bids. Most nowadays would use PEX to replace the old pipe

There should be a water spigot at the bottom of the tank. Hook a hose to that and run/flush water heater to floor drain (do NOT turn water off to heater). Let it run for about 5 minutes. Repeat flushing monthly. The "anode rod" may also be causing the discolored water. It degrades over time. Black specks in water, grey water and rotten egg smells from water heater are common symptoms of this. Even new water heaters can have this problem. Especially if soft water is being fed to water heater. The anode rod may need to be replaced if this is the case. A plumber would need to do this for you. The T&P valve may very well leak now.
RJ

Thanks RJ. I won't do any more for the time being until I can get hold of the plumber who installed the original and the replaced system. I saw the plumber pulled the T&P valve to let the water run out when he was testing the water pressure.

Thanks Ballengerb1. I did not make myself clear. I know it's not a DIY job. I was just wondering how big the job would be. The thought of having walls knocked down depressed me!