If you are experiencing low water pressure where you once had good water pressure there could be several possibilities. The first thing you should check is the supply line, make sure it is turned all the way on. Another common reason is the aerators are clogged, simply unscrew the aerator from the faucet head and clean out the sediment that may have collected by soaking it in vinegar overnight then using an old toothbrush just bush out the buildup. If you are still experiencing low water pressure you should call your plumber for further advise.