100 service connections for 2" pvc pipe 4

[archirodon]

good day to everyone!
i'm a newbie in the field of water distribution working for a water district company.
kindly help me decide whether a 2" diameter pvc pipe is enough for 100 service connections or a 3" pipe is needed.
the pressure in that area is around 5 psi - 10 psi only.

thanks.
romer

 

[RWF7437]

Probably NOT.
How do you get away with such low pressures ? in our part of the world, Oregon, the Health Division requires a minimum of 20 psi and most systems try to maintain 40 psi; especially if fire flows are required.

good luck

 

[bimr]

You can figure 100 gal/day per person and 3.5 persons per household. That would be 35,000 gal/day. Assuming a peaking factor of 4, that would calculate to 97 gal/min.

A 3 inch pipe is probably the better alternative, although it should be noted that the 3 inch pipe is not capable of handling the fire flow requirements.

 

[pittsig]

You should check your governiing regulations.
By statute in NC there is a limit on 2" dia mains :

(a) No more than 20, or the equivalent of 20 residences shall be connected to a two inch diameter water line, unless the main is looped or otherwise supplied from two connections with mains of adequate capacities.
(b) A looped two inch main shall serve no more than 40 residences, or the equivalent water demand of 40 residences. A two inch diameter main shall not exceed 1000 feet in length.

I agree with RWF7437 and bimr posts regarding pressure and fire flow. Backflow could be a problem as well.

 

[cvg]

Water districts I have worked for limited water mains to 6 inch minimum. 6 inch was only allowed for short runs, I believe less than 300 feet. Otherwise 8 inch is the norm. This is generally directly related to fire flow and a short 6 inch line or an 8 inch line can usually provide minimum fire flow requirements.

 

[bimr]

I see that you are from Alaminos City, Philippines.

The water usage is much lower than we experience in our urban areas.

You need to determine the water usage. I suspect that the actual water usage is around 10-20 gallons per day per person.

You can probably get by with the 2 inch pipe. However, you should be aware that the incremental cost for going to the 3 inch pipe is very little and is probably a smart purchase.

You should note that there are a higher number of users on a service drop than in our urban areas.

You also do not have to worry about the fire flows since the houses are constructed of concrete.

Having been to the Philippines and experienced the zero water pressure at the peak demand times, please make sure you put in an adequate system. Otherwise, the users will install pumps in the houses to vacuum out the remaining water in the system.

 

[archirodon]

thanks everyone! good thing i found this site.

(i've included this site in my Favorites!)