I am planning on installing an irrigation system, and I am thinking of replacing the main supply while I am at it. There are also future plans for adding a bathroom on the second floor for the girls.

using this site, http://www.terrylove.com/watersize.htm I come up with 29 fixture units. I can not seem to find what to use for fixture units for the irrigation system though. In my preliminary plans, the largest zone would be 15 GPM.

Distance from city shutoff to the meter in my basement is about 35 feet.

Just looking at GPM, I was thinking of 1 1/4 PE main supply size. If I figured correctly, that would give me 32 GPM. 15 GPM for the irrigation, and leaving 17 for usage in the house.

No permits or inspections required in my town. There are some advantages to living in small town USA.

Current supply is 3/4 copper. 3 houses in the neighborhood have had to replace their supply lines in the past year. I know it does not mean I have to, but I don't want to get my new sidewalks in and landscaping done to only have to replace the supply in 5 years. That is the other reason I am considering it.

Think 1 1/4 is a good size, or should I just bump up to 1 1/2? The only advantage I could see for going with 1 1/2 is being able to run multiple irrigation zones at once, and I can do that with the 1 1/4 if I time it right.

thanks,

Michael