Bad noise from downstairs toilet when flushed. Occasional noise from upstairs en-suite also.Do I have air in the system ? If so how do I rectify. House is 5 years old.

Pump or city water? Describe the noise. Banging? Sequel ? What? Don you have air coming out of your faucets as well? Back to you. Tom

More like a screeching noise which continues until system has refilled with water.Not very mechanically minded to know faucets or pump or city water - sorry.

If you get a water/sewer bill you are city, no bill likely on a well. That type of noise is frequently a fill valve or some other valve. The valve can have a slightly loose washer that vibrates when water passes through. Tell us more.

Thanks for that. Will get it checked out.

You might want to check your Caps Lock key on your keyboard, unclick it. To test to see if the toilet fill valve is the issue is to hold the shaft of the valve while it is refilling. If you feel a tingle then it's the fill valve. If no tingle them holdthe stop valve where the water line comes out of the wall, hold while flushing. Any tingling?