We have low water pressure in our 2-storey, single-family house located in Quebec, near Montreal. The city checked the incoming water flow/pressure and it was normal. A plumber who changed our water heater suggested that the problem was that we have 1/2-in. pipes all over the house and that they should have started with 3/4-in pipes and further reduce to 1/2-in. So my husband decided to upgrade all the pipes to 3/4-in. (from copper to PVC), which had the adverse effect - now we have even lower pressure! What could be the problem? Was the plumber right - should my husband have changed only the first part of the pipes? Is there something we can install to boost the pressure? Help! I'm tired of having to wait until the toilet finishes flushing to rinse the dishes :(.