I'm currently renovating a second floor bathroom. Running from copper that runs into the bathroom to push to connect PEX fittings which are 1/2 in size, then pex and crimp rings with T pieces, elbows, fixtures, etc. I've plumbed the toilet, and four sink lines (for a double sink/vanity) about a month ago. I had the pex lines for the shower in place (and plugged) but had not hooked them up as I was waiting to get a Delta tub/shower valve that I had ordered online. It took me a few weeks to get back to the project and everything else in the house was fine in the meantime. However, the other day, I got the shower/tub valve, and connected it to the water lines. After this, my kitchen sink and laundry tub (which are downstream from the T that goes to the upstairs bathroom), is experiencing low water pressure. Thinking that maybe it had to do with the shower valve, I disconnected the shower valve and plugged the hot and cold water lines to the shower (same way it was prior to the valve installation and low water pressure issues). But.... I'm still having low pressure issues in my kitchen and laundry room! Anyone have any ideas as to what's going on? Any helpful hints will be greatly appreciated!!