Water main piping....yep another one

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Midwest DIY'r

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With the high cost of building anything these days, I'll be doing a mostly all DIY build for our newest (and last) home in North Carolina. The water company offer a 3/4", 1" and 2" meter. The more forum post I read the more I'm getting confused and figured I would just ask the question here.

The home will be approximately 850ft from the city water main, we are planning on building a single story home with a 2.5 baths and an additional wash sink in my shop. There is about a 10ft rise in elevation from the meter location to the home.

What is the recommended meter size and pipe size I should in this scenario? Thanks for the assistance.
 

Jeff H Young

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likely 3/4 assuming no fire protection and pressure is decent but this is a general answer 1 1/4 or 1 1/2 " main personaly doubt 1 inch would be my choice but this is totaly seat of the pants because my minimum would be 1 inch even on a 40 ft run and there is no way Im not up sizing it on 850 ft, Im telling you running bigger meter size likely wont be nessesary depending on all that info you havent disclosed. it can be much more costly for bigger meters and the little e3xperiance I have with utilitys is they charge you more significantly more on monthly bill as well if it was a few hundred bucks one time charge it might be even a no brainer to some but definately check but a 3/4 meter might be absolutely fine
 

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likely 3/4 assuming no fire protection and pressure is decent but this is a general answer 1 1/4 or 1 1/2 " main personaly doubt 1 inch would be my choice but this is totaly seat of the pants because my minimum would be 1 inch even on a 40 ft run and there is no way Im not up sizing it on 850 ft, Im telling you running bigger meter size likely wont be nessesary depending on all that info you havent disclosed. it can be much more costly for bigger meters and the little e3xperiance I have with utilitys is they charge you more significantly more on monthly bill as well if it was a few hundred bucks one time charge it might be even a no brainer to some but definately check but a 3/4 meter might be absolutely fine
Thanks for the reply. The county is charging the following:

3/4" $1500.00
1" 2000.00
2" 3500.00 and requires a RPZ

My initial (uneducated) thought was to go with a 1" meter and 1 1/4" pipe to make the 850ft run. Figured I come here first for the more experienced opinions before I pull the trigger on parts.
 

Jeff H Young

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I havent done any sizing but depending on your needs I think there is a good chance 3/4 is adequate , Thanks for sharing the cost differances 500 bucks isnt crazy amount in the project scope but again might not be nessesary or worth it ( bigger is better if its free) and I think youll see a differance in monthly bill as well .
Some major game changers are Elevation change ( which you provided ) static pressure if you have 100 psi 60 psi or 30 makes a differance in sizing pipe number of fixture units , other water needs irrigation and whether fire sprinklers are required if so I ALLWAYS consult with fire protectin contractor with the needs required by thier aprooved plans from plan check at fire depatrtment. All our homes require fire sprinklers here and generaly share the main but your area likely has differant rules.
 

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I havent done any sizing but depending on your needs I think there is a good chance 3/4 is adequate , Thanks for sharing the cost differances 500 bucks isnt crazy amount in the project scope but again might not be nessesary or worth it ( bigger is better if its free) and I think youll see a differance in monthly bill as well .
Some major game changers are Elevation change ( which you provided ) static pressure if you have 100 psi 60 psi or 30 makes a differance in sizing pipe number of fixture units , other water needs irrigation and whether fire sprinklers are required if so I ALLWAYS consult with fire protectin contractor with the needs required by thier aprooved plans from plan check at fire depatrtment. All our homes require fire sprinklers here and generaly share the main but your area likely has differant rules.

Thanks again, that is valid point on the pressure. I'll contact the water company next week and see what the static pressure is that area. Additionally, we don't have any fire sprinkler requirements in our area.
 

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To echo Jeff, if the home is going to have fire protection sprinklers, then the engineered design for those is going to dictate everything.

Otherwise, here's a little bit of the engineering method that would be used for the fire protection sprinklers, but which applies generally:

1) Start with the minimum pressure that the water company will guarantee at the meter.
2) End with the minimum pressure that a fixture needs to supply water properly. Glancing at IPC Table 604.3, looks like that would be 20psi, the controlling requirement for a tub, shower, or toilet.
3) The difference between (1) and (2) is your available pressure drop budget. It gets consumes by elevation difference (10 ft = 4.3 psi), and frictional losses in the meter, the water lateral, and the piping in the house
4) The frictional losses depend on the flow rate. So for sizing the meter and the water lateral you need a maximum flow rate for the house. There are various ways to come up with that, e.g. the Water Supply Fixture Units method, but they'll all probably give an answer in the range of 10 gpm to 20 gpm or close to it. Making an exact choice here is the part that is most unclear to me.

Then if the budget from (3) after subtracting the elevation difference is say 30 psi, you might decide that you want to allocate 15 psi of that for the meter and the lateral, and the remaining 15 psi for the distribution piping within the house. If your demand from (4) is say 15 gpm, then for each of the meter sizes you are considering, you can look up (ideally with the exact meter model number) the pressure loss through that meter for 15 gpm. Subtract that from your 15 psi budget and you get the allowable pressure drop on your water lateral.

Once you have the water lateral flow and allowable pressure drop, you can use a calculator like this one to tell you the proper pipe size:


E.g. if you have 15 gpm and want at most 10 psi pressure drop, with the 850' length and assuming plastic pipe, the calculator tells you that 1.42" is the minimum allowable inside diameter (which gives 9.9 psi pressure drop). Depending on the style of pipe you are using, the correspondence between nominal size and actual inside diameter will vary, but that likely means a 1-1/2" nominal size.

I'm not saying that this is the size to use, nor that 15 gpm is the correct flow to use, nor that 10 psi pressure drop is the correct pressure drop budget to allow for the water lateral. But I do think that 1-1/2" nominal size is likely in the ball park.

As to the choice of meter size, in addition to the upfront cost you need to consider any difference in monthly fee. Then based on your design flow from (4), you can determine the pressure drop across each size of meter. The basic question then is do I want to spend $X now and $Y / month to gain an additional so many psi of available pressure (reduced pressure drop across the meter)? If there is a monthly fee increase for the larger sizes, there's a good chance that you'd be best off economically going with a 3/4" meter and if necessary upsizing your water lateral to compensate.

Cheers, Wayne
 

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To echo Jeff, if the home is going to have fire protection sprinklers, then the engineered design for those is going to dictate everything.

Otherwise, here's a little bit of the engineering method that would be used for the fire protection sprinklers, but which applies generally:

1) Start with the minimum pressure that the water company will guarantee at the meter.
2) End with the minimum pressure that a fixture needs to supply water properly. Glancing at IPC Table 604.3, looks like that would be 20psi, the controlling requirement for a tub, shower, or toilet.
3) The difference between (1) and (2) is your available pressure drop budget. It gets consumes by elevation difference (10 ft = 4.3 psi), and frictional losses in the meter, the water lateral, and the piping in the house
4) The frictional losses depend on the flow rate. So for sizing the meter and the water lateral you need a maximum flow rate for the house. There are various ways to come up with that, e.g. the Water Supply Fixture Units method, but they'll all probably give an answer in the range of 10 gpm to 20 gpm or close to it. Making an exact choice here is the part that is most unclear to me.

Then if the budget from (3) after subtracting the elevation difference is say 30 psi, you might decide that you want to allocate 15 psi of that for the meter and the lateral, and the remaining 15 psi for the distribution piping within the house. If your demand from (4) is say 15 gpm, then for each of the meter sizes you are considering, you can look up (ideally with the exact meter model number) the pressure loss through that meter for 15 gpm. Subtract that from your 15 psi budget and you get the allowable pressure drop on your water lateral.

Once you have the water lateral flow and allowable pressure drop, you can use a calculator like this one to tell you the proper pipe size:


E.g. if you have 15 gpm and want at most 10 psi pressure drop, with the 850' length and assuming plastic pipe, the calculator tells you that 1.42" is the minimum allowable inside diameter (which gives 9.9 psi pressure drop). Depending on the style of pipe you are using, the correspondence between nominal size and actual inside diameter will vary, but that likely means a 1-1/2" nominal size.

I'm not saying that this is the size to use, nor that 15 gpm is the correct flow to use, nor that 10 psi pressure drop is the correct pressure drop budget to allow for the water lateral. But I do think that 1-1/2" nominal size is likely in the ball park.

As to the choice of meter size, in addition to the upfront cost you need to consider any difference in monthly fee. Then based on your design flow from (4), you can determine the pressure drop across each size of meter. The basic question then is do I want to spend $X now and $Y / month to gain an additional so many psi of available pressure (reduced pressure drop across the meter)? If there is a monthly fee increase for the larger sizes, there's a good chance that you'd be best off economically going with a 3/4" meter and if necessary upsizing your water lateral to compensate.

Cheers, Wayne

Thanks Wayne, lots of good information here. I've tried to reference the plumbing code and if your not in the trade it can be daunting to digest the terms and verbiage. The county did not express a difference monthly cost for upsizing the meter, only the initial upfront cost of purchasing the larger meter prior to installation. I will doublecheck and confirm with the county next week to be sure.

I was looking at using 1" - 1 1/2" SIDR 9 200 psi polyethylene black pipe for the run from the meter to the house, its available in 1000' rolls. This pipe meets the NSF-14/ANSI 61 potable water requirements and seems to be the most cost effective for a large run.
 

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Thanks Wayne, lots of good information here. I've tried to reference the plumbing code and if your not in the trade it can be daunting to digest the terms and verbiage. The county did not express a difference monthly cost for upsizing the meter, only the initial upfront cost of purchasing the larger meter prior to installation. I will doublecheck and confirm with the county next week to be sure.

I was looking at using 1" - 1 1/2" SIDR 9 200 psi polyethylene black pipe for the run from the meter to the house, its available in 1000' rolls. This pipe meets the NSF-14/ANSI 61 potable water requirements and seems to be the most cost effective for a large run

all the places I know charge more per month for bigger meters but I dont deal with this issue often . same with fire sprinklers Im amazed fire protection isnt in homes most of the country it seems.
I wouldnt be suprised at all if 3/4 meter 1 1/4 main to house isnt just fine but no guarantee that your 1 inch and 1 1/2" is suffucient either too little info
 

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Spoke with the county water office this morning, there is no additional monthly charge for the larger meter sizes. The monthly rate is fixed and you pay based on usage, which I thought was fair. The static pressure in our area is between 75-80 psi according to the field installation manager, he said we are only a couple miles from a newly installed tower so he doesn't anticipate any water pressure issues.
 

Jeff H Young

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Thats Good News! Thanks for shareing that I dont hear that often CA likes to penalize construction and water usage
its still 500 more Id say its a no brainer if its a million dollar plus project but a moderate budget project it really could be a bit of waste of money I doubt youll know the differance if you have little to no irrigation and a couple or 3 bathrooms . I might have you mixed up maybe there was a shop with a sink ? thats pretty much nothing but we have no idea how much water you are using it could be a mansion
 

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We are planning on approximately a 2,500ft home with a shop, we also have livestock and will likely have a couple pasture hydrants. In total, I would conservatively say 20 fixtures:

(1) Dishwasher
(1) Washing machine
(3) Toilet
(3) Hose Bib
(3) Pasture Hydrant
(3) Shower Heads
(6) Sinks

With that being said, I now know we can expect 75-80 psi static pressure on the main and we are building 850ft from the water main with a 10ft rise in elevation. I am considering a 1" meter with 1 1/4" polyethylene pipe to the house. Any thoughts or additional inputs?
 

wwhitney

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What I would do next:

Pick a demand flow rate (15 gpm +/- 5 gpm, not sure)
Get the meter model numbers, use them to look up the pressure drop across each meter at the demand flow
Find out the cost difference for 1-1/4" pipe vs 1-1/2" pipe, as well as the IDs.
Calculate the pressure drops through the 1-1/4" pipe vs the 1-1/2" pipe at the demand flow rate.

Now you have 3 meters options and 2 pipe size options (assuming we're correct to narrow it down to 1-1/4" vs 1-1/2"), and you can calculate the cost of each of the 6 combinations. Which lets you make an informed choice of how much you want to spend to reduce pressure drop, and find the optimal way to do that (increase meter size vs increase pipe size).

Cheers, Wayne
 

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The water meter size is typically based on the expected peak water demand for your property. In your case, with a single-story home, 2.5 baths, and an additional wash sink, a 3/4" meter may be sufficient. To estimate your household's peak flow rate, you can add up the flow rates of individual fixtures and appliances. The flow rates are usually measured in gallons per minute (GPM). A licensed plumber can help you with a more accurate calculation based on your specific fixtures and needs.
 

Jeff H Young

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I think doing this research is good even if he contracts job out.
Just a bit more calculating pretty sure though that with a 1 inch meter 1 1/4 would be fine and with 3/4 bumping to 1 1/2 would be good and possibly even 1 1/4" I would not just go big until I actually sized it
 

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After some basic flow rate calculations using some online references on fixtures I arrive at a peak demand of 100 gpm (or close). This could be entirely wrong, but my attempt to figure this out.
 

wwhitney

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After some basic flow rate calculations using some online references on fixtures I arrive at a peak demand of 100 gpm (or close). This could be entirely wrong, but my attempt to figure this out.
Yeah, that's totally wrong for a house. It might be what you get from adding up the peak demand for all of your fixtures, but you'll never have all your fixtures at peak flow simultaneously.

The Water Supply Fixture Unit method found in IPC Appendix E is one option. NC hasn't adopted Appendix E of the IPC, but that doesn't mean it's not a reasonable method to use. You add up the WSFUs for the fixtures, and then use a non-linear conversion from WSFU to gpms. The resulting peak gpms still seems high to me, but I guess it depends on occupant load. E.g. the assumption is that if 2 people live in a 4 bathroom house, sometimes you are going to be entertaining 10 or 20 people and 3 or 4 bathrooms may see simultaneous use.

You can see IPC Appendix E here for example:


Cheers, Wayne
 

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Yeah, that's totally wrong for a house. It might be what you get from adding up the peak demand for all of your fixtures, but you'll never have all your fixtures at peak flow simultaneously.

The Water Supply Fixture Unit method found in IPC Appendix E is one option. NC hasn't adopted Appendix E of the IPC, but that doesn't mean it's not a reasonable method to use. You add up the WSFUs for the fixtures, and then use a non-linear conversion from WSFU to gpms. The resulting peak gpms still seems high to me, but I guess it depends on occupant load. E.g. the assumption is that if 2 people live in a 4 bathroom house, sometimes you are going to be entertaining 10 or 20 people and 3 or 4 bathrooms may see simultaneous use.

You can see IPC Appendix E here for example:


Cheers, Wayne

Thanks Wayne, looks like I have some reading to do to get this figured out correctly. I appreciate the resources.
 
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