Low water pressure

I have low water pressure in house, i have replaced tank

I have low water pressure in my house. This just started recently. I have replaced pressure tank with no luck.

I assume you have your own well...you haven't given much info. Check the pressure gauge - what are the low and high settings for the pump? Is the pump running most of the time? Cycling on and off frequently in short cycles when no water is used or while you are running water?

Lots of possible reasons, but you need to cough up more description of your system before anyone can help.

When you got the new tank, did you scrap out the old Chinese gate valve? Those have a short life and the gate in them can break off and obstruct the flow.