We have a 3/4" copper supply from the meter in the street to the basement that is the original 1968 pipe. I'm guessing that scale has accumulated over the years, even though we don't have especially hard water.

Is there a way that I can descale it since the water company has no responsibility for it?

no need

if you are 'worried' simply flush it (until it runs chystal clear) wide open with a 'disconnect' somewhere

if it does NOT flush clear THEN you may, or may not, have an issue depending on exactly WHAT the discoloration actually is

municipal water 'generally' is perfectly safe and actually PREFERRED over bottled

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I would not worry about it.

Thanks. I should have been clearer. My concern is restricted flow. Pressure is good, 65 PSI, but don't know if flow is impaired or how to measure it and determine if scale is reducing flow in the main supply to the house. Thoughts?

Cu tube does not 'scale' to any apreciable extent other than enough to affect heat transfer.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

>Pressure is good, 65 PSI, but don't know if flow is impaired

Vacuum the dust off your refrigerator cooling coils. Wash your AC condenser coils. Clean your gutters. There's nothing to see in your water pipes.