how to clean the scales in the inner side of water pipes?

Question

scales have formed due use of hard water.

Answer 1

If your pipe is galvanized steel, there is no satisfactory method; suggest replacing the pipe. The new plastic pipes are less likely to accumulate scale.

Answer 2

Make sure it's just scales first. If they are galvanized pipes, it could also be rust buildup and if it is, you'll need to replace them with copper pipes. Do a test by flattening a heavy gauge metal coat hanger on one end (after the loop is cut) and form a hook like a long shank fishing hook. Find a union coupling in your water piping and remove it. Stuff the hanger hook down the pipe and scrape the inside sides vigorously. If you get good amount of brown rust, say goodby and get copper pipes.
If not get couple of gallons of muriatic acid (Home Depot), disconnect the main house water valve and let the water in the pipes drain out. Make sure you open all faucets and disconnec the water hoses to your washer. You will need a low power water pump (very inexpensive) and pump in the muriatic acid until it starts to come out of faucets and other disconnected fixtures. Stop the pump an let it sit for couple of hours for the muriatic acid to dissolve the scales. Reconnect the water line and turn it on. Open the faucet slowly and see if the water pressure has improved. You should also see the gunky remnants of the scales. If the improvement is not up close to the original pressure, repeat with increased soak time until desired pressure is obtained.
Good luck.

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