Plastic water pipes bang.

That'd be my guess. Normally the pipes will be tied to joists at regular intervals to hold them steady.

Possible the are loose. Hot water will cause the pipes to expand as the water goes through and heat them. It may be possible to re-route or add a couple of elbows as expansion loops to prevent some of it.

Early every morning? Is this just happening in the shower by any chance? If so, the cold side of the shower mixer (I'm betting it's a Delta) is probably set too low. Crank it up slightly and that should cure it. The adjustments are located behind the coverplate. pry off the center cap of the knob, and remove the screw that holds the knob. Pull the knob off, and remove the two phillips head screws under the shaft. Pull off the coverplate and you will see the adjustment valves on the left and right of the mixer. They are operated with a flat blade screwdriver. The one on the right is the cold water. Just turn it counter-clockwise a little. You can temporarily put the knob back on without the retaining screw to test the results. Do not go crazy and turn it a lot at once. It won't take much of an adjustment to get rid of the drum solo.

Commodore Joe Redcloud

If it's a new home is there a warranty? If you just bought it there might a disclosure issue?

No - not just the shower. And no - the house is 5 years old. I just have lived with it for a long time and now I want to eliminate it. Thanks

Geezer

Do you have hard water ?

Next time you hear the noise, go stand by the water heater......

Our water has suspended minerals. It settles ( and cakes ) in the water heater. When the water heater kicks on, it clunks, grumbles and growls.

...no...flushing the heater doesn't get it out.

Could be too loose or too tight. The plastic pipes expand when they get hot so they move. The need to be able to move yet be securely attached.

You might want to go to the basement and let someone turn on the hot water and track down exactly where the noise is coming from. If they are so loose as to flop around you need to secure them better, if the can't move at all (along their length) then you may need to provide that ability. If you have long runs and if the elbows are tightly secured that could be a problem.

Good luck