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Water line size

Water line size

Water line size

I did some structural work for a client and he asked me about installing a 2,500 foot water line from the town main to his building. The building is approximately 70' above the water main. Will a 1" plastic water line be big enough?

RE: Water line size

It depends. How much water does he want and what is the town mains working pressure.

You will have to have at least about 30 psi or 210 kpa at the town main to get any flow at all. If you had about 45 psi or 300kpa at the town main you might get about 4USGPM out the end.

"Any water can be made potable if you filter it through enough money"

RE: Water line size

Ashtree's analysis is spot on. Here are some other things to consider:

Is the town even going to allow extending their system to your client's building? Is it even legal in your locale?

If so, is the town going to require the pipe to be sized for fire protection demands.

If so, how large of a fire flow would they require?

The peak water demand for single building can range from a few gallons per minutes to thousands of gallons per minute (e.g. a large factory). Fire sprinkler demands might be in the hundreds of gallons per minute range and fire hydrant flow requirements can be hundreds to thousands of gallons per minute.

In any case, a long dead-end pipeline will be prone to water quality problems if the demand is low, especially if the pipe is sized for fire protection.

"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

RE: Water line size

All these comments apply to the exterior water main requirements.

You also need to look at the interior.

If the building is residential, 1" is likely too big unless it is an apartment building.

If the building is commercial or industrial, 1" is likely too small, even if it is only for plumbing. If the building has flush valve water closets, a 1.5" is minimum, a 2" is better. You need to know what is being used inside (how many fixtures and the types), what the local plumbing code requires for pressure (IPC requires 35 psig static for water closets).

RE: Water line size

The minimum water size for a 3,000 square feet McMansion in the suburbs is now 1-Inch.

Unless there is a single bathroom in the building, 1-Inch will not be adequate.

RE: Water line size

When installing long service lines I usually recommend using 1-1/2" to 2" pipe to reduce head loss. There typically isn't that much difference in the cost of the pipe compared to the total cost of installation.

RE: Water line size

Wait right there - you are running a half mile of water line from the existing water main to the new building? 1 inch is laughable, you won't even get a trickle through that due to the friction losses. It'd recommend at least 3" in diameter, and even larger if he needs fire protection.

Run the calcs yourself using some free flow/friction loss software online.

RE: Water line size

you might have a 1 inch service meter, at the point of connection, but you will likely require a much bigger line to the building. don't go too big though, you do not want water standing in that half mile long pipe for long periods of time or the water quality will suffer.

RE: Water line size

You may consider the line filling into a storage tank (non-pressurized, atmospheric tank) and then re-pressurize with a booster pump to serve the building. This method will guarantee you the desired flowrate & pressure. See this simple diagram:

Chris Eberly, PE

RE: Water line size

On cneberly's sketch, what is missing is some form of flow / pressure control arrangement to initially bring the pump online and then shut the pump down when there is no demand.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Water line size

I'm inclined to agree with the others that a 1" line looks too small. Not only do you need to consider the 2,500 feet of pipe, but you are changing the elevation by 70 feet, and that's just to get to the building. At the building it need to be able to go up another 12'+ and the internal plumbing. Other pressure losses will be from fittings such as shut-off valves, check valves, backflow preventer and meter to name a few; elbows and bends in the pipe will add to the pressure loss as well.

But you're getting ahead of yourself, you really need to know the building's water demand requirements before you can calculate all this which will depend on the volume of water through the pipe.

Regarding the booster pump, I'd wager if you have less than 50 psi at the main, you will need a booster pump.

One thing is certain, you need to run some calculations or risk having to tear the 1" pipe out to install something larger.

RE: Water line size

cneberly : Clarifying the pump used makes the difference, as the unit shown on you initial sketch doesn't indicate stop/start arrangement.
But good choice, what would enhance the installation is an appropriately sized bladder pressure tank for an installation that has intermittent, short supply demand such as a house / apartment, small office, small factory etc. - the pump doesn't need to come on each time someone want a drink of water or a quick wash of their hands etc.

The video is an excellent presentation , thanks for the share - many years since I visited Grundfos site.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Water line size

jimtheengineer10: for pipe size I wouldn't consider anything under 1.5" and preferably 2" depending on minimum the mains pressure.
You really need to calculate the total system head thru' the line from the main to the highest point in the building.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Water line size

Agree with Artisi & Dbill74.
I'm from Texas, where "bigger is better". In the case of pipe sizes, the additional cost of upsizing the pipe size is often insignificant since the labor cost ia about the same to install 1" vs 2" pipe. It is common to use a day tank where your supply is limited. For example, we have a ranch in west Texas where the water well can only produce 3 gpm due to the well depth and geological conditions. To serve a lodge and additional houses, we need to have at least 20 gpm water. The solution is to provide a day tank (often referred to as surge tank, breaktank, or storage tank)with a booster pump to re-pressurize the water to serve the buildings.

Just remember, you can always upsize the pumps & tanks. Upsizing the plumbing piping inside of a building could be cost prohibitive if you choose to do it later. So, put in the larger pipe size early!

Chris Eberly, PE

RE: Water line size

Do really have 2 options depending on the water authority view of your requirements.

1. Small diameter pipe to a storage tank with a local booster pump
2.larger diameter pipe to supply directly to the building.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Water line size

For pipe size ,large will be better . You can weld the pipe below your tank .

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