Question about replacing water main

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Chet

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I live out in the boonies in a house I inherited in northeast Texas. About once a year I have a failure on my main line and I have to do a repair due to the ground shifting in the summer. I'm sick of these repairs and want to replace the entire line.
My water meter is on the very corner of my property, from the meter to my house runs about 350 feet (I do have a shut off in my yard).
I plan to rent a trencher and move a few feet over from where the old line is, running a new trench with a new line, and I'll just have to make up the differences on the ends with some elbows and such. The pipe in the ground is 3/4" PVC bell end, which I plan to replace with the same.

I have access to quite a bit of 2" IPS gas line for free, and I my question here is, would there be any issue running the replacement water line through the 2" tubing, then placing it into the trench with sand bedding? My thought process here is that it would create a buffer for the movement of the ground and be less likely to cause breaks, but I've never done anything like this so I have no idea if that's the case. Can anyone offer any insight?
 

Terry

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You should run at least 1-1/4" piping and 1-1/2" would be even better for that distance.
Having it inside of the 2" if it fits would give it some protection.

pipe_size_2.jpg
 

Chet

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I appreciate your quick reply, and please be aware I'm fairly ignorant when it comes to plumbing. I understand that the larger pipe will deliver more pressure to my house, however, if I have never had any pressure related issues up to this point and have no plans on adding anything that would affect pressure needs.
In this specific case, am I doing any harm by just replacing it with what is there? It looks like going up to 1 1/4" would double the price and I don't have a lot to work with at this time.
 

wwhitney

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I understand that the larger pipe will deliver more pressure to my house.
So, when you're not using water, the pressure at your house is going to be the same no matter what size pipe your water lateral is. When you turn on the tap to fill your bathtub, the pressure at the end of the water lateral is going to drop. With a smaller pipe the pressure will drop more (and you'll get less flow); with a larger pipe, the pressure will drop less (and you'll get more flow).

If you want to see this in action, and you have a hose bibb near where the water lateral enters your house, and a pressure gauge, check the pressure there while no water is being used (that's called the static pressure). Then turn on your bathtub (or whatever other large water use you have, say irrigation), and check the pressure again. The difference tells you how much pressure is lost due to your water lateral; the reading is the remaining pressure that is pushing water through your house piping. If the water lateral pressure drop is a big fraction of the static pressure, you may benefit from a larger size water lateral.

On the other hand, if your pressure at the water main is crazy high (like 100 psi) and you have a pressure reducing valve anyway (in which case the measurements above should be taken before the pressure reducing valve, if possible), you might find that the pressure loss due to your lateral just isn't a problem for your flow demands.

Cheers, Wayne
 
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