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Starting Member

Posts: 1

Location: USA


Saturday, February 21st 2004, 1:11am

tapping mainline to larger sprinkler line

I am designing a new sprinkler system and want to increase my flow/GPM. I hear I can do this by tapping off my 3/4" mainline (with a compression tee?) to a 1" line for the system. Is this OK? What is the best way to tap into my current mainline (with 5/8" city meter at the street) if I am going to increase the size of the sprinkler line? [?]


Supreme Member

Posts: 456

Location: USA


Saturday, February 21st 2004, 4:31am

I am assuming that you are in the southern part of the state. The best answer I can give you is, get it done right the first time and soldier a copper tee on rather than using a compression tee. The copper will last alot longer then the compression tee.


Supreme Member


Saturday, February 21st 2004, 5:34am

Another important benefit is that the flow velocity will DECREASE also by upsizing your mainline. This has the added benefit of greatly reducing water hammer.

I would only design for a maximum of 10 gpm due to the 5/8" meter.

Like rvli said, do it right the first time and solder on a copper tee. You should be able to use a 3/4" x 1" bull nose tee.


Supreme Member


Monday, February 23rd 2004, 8:36am

There is nothing wrong with taping into a 3/4" mainline to start a 1" mainline for irrigation. You just want to tap into the main as close to the meter as possible. While there are other considerations (and these are the things that will limit your design to less than 10gpm), the main thing to worry about is pressure loss. The longer the water has to travel through a 3/4" mainline, the more pressure you are going to lose. For example: assuming a flow of 10 gpm, for every 100 feet of 3/4" copper (Type K) pipe, you lose over 14psi of pressure. But a 1" pipe will lose less than 4psi for the same distance.

Assuming we're talking about a mainline and meter that are burried in the yard...

How to you cut into the mainline to insert the copper tee? Since all of this is burried, you're not going to be able to push the ends of the cut the 3" apart needed to insert them into a copper tee. Even if you expose enough main line to allow some latteral seperation to like the tee on the way those instruction books show with a compression tee, the stops inside the fitting are going to prevent you from completing the connection.

Given that copper fittings have stops in them, I see only one way the geometry of this is going to work. 1. You build a special purpose fitting by connecting two 90 degree elbows (pointed in the same direction) to each end of a copper tee with short pieces of pipe (maybe even really short if you use street elbows). 2. Cut a section out of the mainline and soilder a pair of 90 degree elbows (pointed in the same direcition) such that distance between these elbows matches the distance between the elbows of your special purpose fitting. 3. Now you can soilder the elbows all together with two short pieces of pipe.
For those that might have difficulty visuallizing the finished product, follow this word picture of the flow of water. The water leaves the meter and makes a left turn followed by a right turn, through the tee for the irrigation system, then a right turn followed by a left turn, then on into the house.

Now using this many elbows seems like an ugly kluge and I hope someone has a better solition.

I have one other alternate idea, but I curious what input others have first.


Supreme Member


Monday, February 23rd 2004, 9:11am

besides your tee, you need a 3/4" REPAIR coupling. A repair coupling has no stops so that you can slide the whole coupling over the pipe. This will give you the needed space.


Supreme Member


Monday, February 23rd 2004, 6:12pm

The repair coupling was my other idea, but you have to make sure you flux it all up real good before putting the stuff together.

rain man

Active Member


Tuesday, February 24th 2004, 1:15pm

Your water meter size and static water pressure will determine your flow rate (gpm), while your increased pipe size will only reduce your pressure losses due to friction. Do you have your static water pressure?

-rain man

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