I was asked at a job interview today what the maximum allowable 90 degree elbows permitted on 1/2inch copper. I didn't know the answer. Fortunately neither did the interviewer. However I was hoping someone could tell me because the **** question is stuck in my head.

Your post got my curiosity up so I wrote to The state of Ky. and this is what happened.

To: EPPC Plumbing (EPPC DPP HBC)
Subject: Question on half inch supply lines



In a recent discussion the question of "What is the maximum number of 90 degree turns are allowed in a 1/2" water supply line" was asked. No one there seemed to know the answer. I suggested that it shouldn't matter but that the number be kept to the min. needed for the application. Was I right or is there a specific number and if 'yes' would it depend on where you live?


"There is not a maximum number of 90 degree fitting requirement, other than keeping all fittings to a minimum."



Dennis Rodgers

Field Operations Manager

Division of Plumbing

Office of Housing, Buildings and Construction

502-573-0397 ext. 302

I hope this helps you.

Of course the fewer 90s you have, the less friction(more water flow) you have. I've never heard of a maximum either for water piping. But like Paul said, the fewer the better. You wouldn't notice the difference in a normal house if you use a few more than needed.

With the cost of metal going up, the less copper you use, the cheaper it is