I bought an 8 year old house and am thinking abiut adding a bathroom. I have gotten a permit and was reafing where pressure checks are done for new plimbing. I kind of got worried when I read this in the sense that if there is some minor leak anywhere in the house will it show up on the test. Worried if there is whetjer I might need to find leak and redo plumbing.

I am not aware of any leaks bit just worried. I don't need the bathroom but would like to add it to unfinished space.

Thanks for the advice

You will be testing only new plumbing - drains, plumbing vents and gas lines. You have to rough it in first, then cap it off before you connect new and old, and have it pressure tested for inspection. Once the rough inspection is signed off, you can connect all pipes with existing. Hot and Cold water can be connected right away. Existing plumbing is not tested.

Hope that helps

Milo

So I hook uo all plumbing together but don't tie I'm the drain line for example to the old drain? What about installing thecfixtures and tub before or after the inspection? If I'm running plumbing through floor do I keep floor open?

Correct.

Water can be connected right away.

Drains and Vents you glue together but do not connect with existing. Plug all outlets with plugs. Fill them up with water for inspection. You will have to cut connection to the existing at the point of planned connection - and install transition fitting. That should also be ready for rough inspection as Inspector wants to see how you going to connect new and old.

As far as gas goes, you do the same. Rough in all gas piping and do not connect. Cap off all ends and fill with 10 PSI of air. Connect after inspection

Hope that explains

Milo

Thanks. What is a transition fitting? What about installing tub And toilet and vanity?

You will need to transit from NEW to EXISTING. You will cut in a fitting ( as per previously posted visual ) at the point of intended connection. That fitting we call "transitional" fitting.

Toilet, tub, and all other fixtures are installed after rough-in inspection. Enclosed video shows how you cut-in "Y" into existing sewer pipe.

https://youtu.be/CC-S0kSRlfc

Milo

For what I'm trying to do would I need to use a fernco? Once I cut into existing horizontal drain I should use fernco to comnect to wye? So basically you are saying the existing horizontal piece should have wye attached but not connected to the new vertical drain? And I cap off the bottom of the vertical drain for insoection? If they fill uo with water then how will I get that out once I need to connect everyrhin together?

All new plumbing should have all outlets capped off and filled with water for inspection purposes. Yes, you cut in new Y connection at the point of intended connection so Inspector see how you going to connect new and existing drain pipes. As far as water removal goes after the test is approved - you install test plug with hose valve attached to it. Once inspection is over, you will attach a hose to that valve and drain the system.

Hope that helps

Milo