Sizing A Water Main: Use Our Free Water Line Size Calculator Service

[@roberthernandez1985]

You have to be careful when you give out raw numbers like that it really does depend on a few things a 1” line can deliver a lot more than 9GPM in fact if you had 200 psi behind that 1” line you can probably deliver 30 gallons per minute how many CV across the regulator inside the house? The real Answer is that it he PRV inside the house limits the pressure down to 80 static and that will affect your overall delivery pressure so what you should be able telling people is that at 80 psi static you can deliver an average of 9gpm to your total fixtures but even then elbows valves and other things like total amount of piping effects pressure drop and flow rates

[@workingshlub8861]

i only 3/4 coming into my home and then 1/2 right after meter...had good pressure at 60lbs but terrible flow with multiple fixtures going....i tore out the 1/2 and did 3/4 until all the branch offs and it made a huge difference.i also replaced pressure reducer valve ..those can go bad also.

[@RogerBarraud]

Hey, this is great! 🙂 Wish you were my local guy... but I'm in NZ 🙂 Cheers!

[@balkanplumbing]

Thanks! Roger on that:)

[@galecooney2337]

So a 2 inch line would suffice for 200 ft. length with 4 foot elevation change at last 20 feet??

[@balkanplumbing]

You would have to provide the type and number of plumbers fixtures for an intelligent answer. Plus, all answers are based upon the NYC sizing table.

[@peterfingerson9790]

Hello there, I am building a house out in eastern Kentucky. Our house will be about 1800' from the city water hookup. There will be an elevation gain of approximately 100-150'. The house is only a 2br, 1bath, with an outside shower and outside hose hookup. We have been told that a 2" line would be best, but I wasn't sure if that seemed correct. Would a 1" be sufficient pressure for that much distance? Also, would a 1" meter work with that 2" line, or would we need to get a 2" meter? Thank you for any and all help!

[@trohobbs]

I have been wondering about this for years. When I water my grass I can’t even take a shower. The water pressure drops too low. So I’m going to increase to a 1 1/2 inch line. I’m at a 3/4 pipe now

[@balkanplumbing]

Before you go that expense, I might be able to help you out. Let me know how many bathrooms and kitchens you have in your home, and the distance from your home to the city main in the street. I'll size out what size water service line you should need. If you do go ahead, you may need to to change the tap connection on the city main too!

[@trohobbs]

@@balkanplumbing we have a 3 bedroom 1 bath. But we are increasing to 4 bedroom 3 bath.

[@trohobbs]

@@balkanplumbing the distance from the meter to the house is about 35 feet.

[@balkanplumbing]

@@trohobbs Also how many bathrooms and how many kitchens?

[@balkanplumbing]

if you have 1 kitchen, 3 full bathrooms, a dishwasher, and a washing machine 1 1/4" would be perfectly fine for a 35' run. Just make sure the tap connection on the city main is at least 3/4" of an inch, a 1" tap connection would be ideal. Hope that helps. if it does, please give my video a "like"!

[@hurleysjumpzone9533]

I am starting a mobile home park. There will be 12 mobile homes hooked up to my main water supply. These homes will be 2 bed 2 bath. The main water line will be ran 650 feet from the city line to the first mobile home. From 650 to 1050 feet the homes will be hooked up into the main supply. What size main water supply do I need? A lot of people are telling me 2 inch line or 3 inch line

[@balkanplumbing]

Using calculations based upon NYC sizing requirements, you clearly need a 3" main. A 2" main will be even close to sufficient. This is based upon information you supplied of an average length of run of 850', and 2 bathrooms and 1 kitchen per unit. I hope that helps you. BTW Better to do it right the first time!

[@hurleysjumpzone9533]

Thank you!

[@bertraminc9412]

If you have a 3/4" supply line from the city and you put a 1" line from the meter to your home, are you really getting more flow rate or less friction when the city is already using a 3/4" line? I don't think so. If the city is using 3/4" and you put a 1" to the home you are getting no benefit from using a 1" from the meter to the house.

[@charlesterrizzi8311]

Youd have a better supply of water contained in the larger pipe, it would of course be better to have it all the way, but every place it can be bigger would help. Friction loss and volume.

[@bertraminc9412]

Charles Terrizzi Ok.

[@workingshlub8861]

you dont want any line bigger than what is before the meter coming from the street..

[@PULSEXBillionzz]

hey im trying 2 figure out waterline size anD hope u can give me an idea. im in the philippines and lets say they r not overly smart anD im no engineer so that being said. they have an inch and half main line 2 our area with about 2o half inch lines connected. it seems 2 me thats not a big enuff main line. the water source is several miles up hill no pump gravity feed. is there a way to est how big of line there should be? ty Travis

[@balkanplumbing]

Wow Travis, from the Philippines! That's awesome. My sizing table is based upon the NYC requirements. It is based upon the number of plumbing fixtures (bathrooms, kitchens, etc.) and the length of the run of pipe for the service line. The minimum size for a service line in NYC is 1". With that said, I'd have to agree with you that 20 lines connecting to one 1 1/2" line would not function properly. A 2" line feeding 20 homes with 1 bathroom and 1 kitchen each should be fine. The service lines feeding each house should be 3/4" or 1" in my opinion. Remember I have no familiarity with plumbing code or requirements in your area. Let me know if that helps in some way, and thanks for the inquiry.

[@PULSEXBillionzz]

@@balkanplumbing Codes?, thats a funny word here..lol .. if there are, they dont follow, im sure... Most foreigners that come here with any knowledge of plumbing, electrical, mechanical, maintenance just shake their heads at how things are done. people live 4 the day the heck with 2 mrw so it really doesnt matter how it gets done or if its done right or wrong as long as its done.. Its a very different world..lol. so anyway just as i figured common since says not big enough main.. Ty 4 ur feed back.

[@jordanwagner3613]

Thanks for the video, really helpful. What size would you use for a 300 sq. ft ADU used for airbnb? It has an existing water line that needs to be repaired that runs from the back of the house so I was thinking of upgrading it.

[@balkanplumbing]

The main water service line size is calculated by the number and type of plumbing fixtures. I would need that information, and if you are indeed referring to your main water supply line.

[@jordanwagner3613]

@@balkanplumbing I checked and it is the main water line supply. As far as plumbing fixtures, I believe it would just be a kitchen sink, bathroom sink, shower, and a toilet. Thanks for your reply, I'll try passing this video to a few friends in this area in the event they ever need help.

[@richardp4481]

I have a 2000ft driveway with a 3/4 in meter. I’ve heard 1in supply line is fine and I’ve been told 2 in would be better. No elevation change. What is your thoughts

[@balkanplumbing]

Required size is also calculated by the plumbing fixtures in your property. How many bathrooms, kitchens, washing machine, dishwasher. It all is needed to size the iine properly. BTW: A 2,000' driveway? You sure?

[@nova31337]

@@balkanplumbing probably a ways inside of a 40 acre property. It's uncommon, but some rural areas have city water service.

[@erikkatz858]

can I go straight from 1 inch or 1 1/4 inch to half inch for my branches, or do I have to step it down?

[@balkanplumbing]

That is where yo have to be familiar with plumbing design and code. I cannot answer that, better to call a local pro.

[@portlandlocalchurch8168]

The city has given me an option of a 3/4 in water meter or a 1 inch water meter the 1-in water meter costs quite a bit more and my house is 500 ft up a driveway from where the water meter is going to be I was told to use a 2 inch water line because otherwise I would have very low pressure up at the house but does the water meter size itself matter in my scenario?

[@balkanplumbing]

Yes the meter size matters a lot. Rule of thumb, the meter size is 1 size smaller than the service line size. Meaning, 2” service line, then 1 1/2” meter. Btw: 500’ high, you might need a pump with a holding tank. Let me know if that makes sense!

[@portlandlocalchurch8168]

@@balkanplumbing I'm sorry if it sounded like the house was 500 ft high,, the driveway is several hundred feet long and the house is about 500 ft from the main road where the water meter is and the house level is probably 15 ft higher in elevation then the elevation at the main road where the meter will be

[@balkanplumbing]

@@portlandlocalchurch8168 I can actually size the line out for you if you give me the number of bathrooms and kitchens inside the building. I'll base it on a 500' run.

[@portlandlocalchurch8168]

@@balkanplumbing the home is a HiLine 4br plan #2576 with 2.5 restrooms and 1.5 kitchens and I was told that we have 68#psi at the main line, down on the road.

[@balkanplumbing]

@@portlandlocalchurch8168 I would need the distance form the building to the public water main to do a calculation based upon the NYC sizing table. Please give me the distance.

[@MrSmartass89]

What you are saying is great information, however it does no good to put a larger diameter pipe on your side of the meter than what is on the city side of the meter. If the city side is 1" or 11/4", you simply match that on your side. A larger diameter pipe on your side of the meter than what is on the city side will not do you any good. One trick we use is to continue with the same diameter pipe from the meter, and running it far underneath the house. Then go with 3/4" as far as we can, then dropping it down to 1/2" to accommodate the fixtures. Gotta have that volume. Also, use garden valves instead of hose spigots. Huge difference. Thank you.

[@stevelovesgod]

No one listen to this guy, he's clearly not a plumber. Many high rises have supply pipes that are 2 sizes larger than meter

[@stevendavison8525]

@@stevelovesgod for real he just contradicted himself. A larger pipe after the meter means more volume.

[@mariusm3595]

1" line = 9 GPM at what PSI ?

[@balkanplumbing]

This sizing guideline is based upon the NYC sizing table. I am not sure what PSI they (the DEP) used in determining the size.

[@roberthernandez1985]

Ya you can’t throw around raw numbers without understanding what your static pressure is and what amount of pressure drop due to friction etc you can have 30 GPM on a 1” line if you raise the static pressure high enough it just means you’ll have way more pressure drop over short distance you can basically start your calculation off 80 psi for whatever size pipe cause the pressure reducing valve in the house will limit static delivery pressure to 80