I purchased my home (new construction) in Nov 2007. Last summer the water heater was replaced because the pilot light would not stay lit. (Water heater was 1.5 years old). Within 6 months of the new water heater being installed I started noticing greasy black flecks in the master bath tub when filling the tub. I only see the flecks in this particular tub (there are 4 in the house), no sinks, toilets, dishwasher, or laundry machines. I only see the flecks when using hot water. The water heater was drained, blown out with a compresser and a hose replaced (metal bendable hose that looked brass in color). The flecks have not gone away and no one has been able to determine what is causing it. I am also (to my knowledge) the only one in the neighborhood having the problem.

Thanks

Describe the black flecks.
Can you squash them? Are they hard with edges? Any smell to them? Is there a hot water circulating system installed?
How about a water softener? Got one of those?
Back to you, Tom

Yes, they can be smeared. They have no odor. They float on the surface of the water and cling to the edge of the tub. The harder flecks stay in the screen of the faucet, but I don't recall them having hard edges and are the size of a grain of sand. We do have a circulating system; however, it has not been used. We do not have a water softener.

Thanks.

What type of tub valve is on your tub? Its possible that the rubber seat is wearing out and releasing these small black fragments. Check the stem for any wear.

I only see the flecks in this particular tub (there are 4 in the house), no sinks, toilets, dishwasher, or laundry machines. I only see the flecks when using hot water
This would seem to place the problem on the tub valve.
Answer Trucks question and tell us what brand tub valve you have.
One handle or two knobs? This could be a washer or "O" ring breaking down. Cheers, Tom

Are you on a well or city supplied water?

If on a well, a house filter should remove the debris.

Manhattan,
Go back and read the first post.in which he says;

I only see the flecks in this particular tub (there are 4 in the house), no sinks, toilets, dishwasher, or laundry machines
If it were coming from a well he'd have it in all his faucets. Cheers, Tom

I have a kohler tub (no jets) and moen fixtures. The moen fixture is two handled (obviously one hot and one cold) and a swan neck style spout and all three pieces stand independent on the tub surround surface. Thanks.

I would suggest that you start by changing the cartridges in your tub faucet.
You stated that you are not using your recirc system. Does that mean no power to the pump or the valves for it are shut off? Is it piped with this tub being the furthest fixture? Is this the end of the recirc loop? IF so, is the recirc piped going back into the heater at the drain on the bottom of the heater or the cold inlet on top? I ask because I had a call with a similar situation. Their master tub was the fixture at the end of the recirc line and it kept getting crud in it. I moved the recirc return line from the drain to the cold water inlet (with a check valve installed of course) and the problem was solved. I also showed the customer how to flush his water heater as Speedie is so good at explaining.