New Well - How much gpm should I need?

[D C]

New well for new construction.
I've got quotes from 2 companies, both of which are quoting 5" wells, which are typical in the area. I expect the well to be 100-150' deep based on others in the area.

I've been offered a 3/4 hp pump at 10 gpm, or an upgrade to a 1 hp of unknown flow rate.

My only reference point is that in my current house, I have a 3/4 hp pump, set around 150' and a 44ish gal tank. Everything seems ok, but I sure wouldn't complain about more volume for the shower. The system runs 4-5 sprinkler heads with no issues, so it's ok overall, no real complaints.

How do I decide how much flow I need, and how big of a tank to get? I do plan to have a multiple-head, multiple-valve master shower with 2 valves minimum, possibly more with 3/4" or larger. That's my only real high demand. I'll have a sprinkler system, but I don't exactly need to water the entire lawn at once.

Thanks in advance!
Dave

 

[Reach4]

I've got quotes from 2 companies, both of which are quoting 5" wells, which are typical in the area. I expect the well to be 100-150' deep based on others in the area.

I've been offered a 3/4 hp pump at 10 gpm, or an upgrade to a 1 hp of unknown flow rate.

The important part in sizing the pump HP to the flow is the depth to water, called the static water level when not drawing water. When you draw water, the level will drop some, but maybe not much.

10 GPM is probably a good nominal size for you, although 7 is good for many.
A 1/2 HP 10 GPM may be best if your water level is 75 ft or closer. A 1/2 would even work if your water level fell to 100 ft with a 40/60 PSI system giving you 8.8 GPM at 40 PSI and still would able to shut the pump off at 60 PSI when you stopped using water. A 3/4 would have more than enough lift for the well you envision. 1 HP 10 GPM would be more power than ideal for this.

 

[Sponsor]

 

[PumpMd]

The 1hp 10gpm pump will let you run more faucets at the same time for outside watering. In the house, you won't see a difference between the 3/4hp 10gpm and 1hp 10gpm.

 

[D C]

Thanks guys. Didn't know what gpm the 1 hp pump would be. Sounds like it'll be beneficial, and the decision on which pump will be more of a factor of the depth that the pump sits at than anything. That 10 gpm @ 60 psi sure looks nice though!

How about tank size? It's just an accumulator really. Seems that with a big enough pump and a big enough flow (thinking in terms of a double+ shower running) once the tank is drained and the pump takes over, tank size doesn't matter much.

 

[Craigpump]

Thanks guys. Didn't know what gpm the 1 hp pump would be. Sounds like it'll be beneficial, and the decision on which pump will be more of a factor of the depth that the pump sits at than anything. That 10 gpm @ 60 psi sure looks nice though!

How about tank size? It's just an accumulator really. Seems that with a big enough pump and a big enough flow (thinking in terms of a double+ shower running) once the tank is drained and the pump takes over, tank size doesn't matter much.

Use a cycle stop valve with a WX202

I admit I was skeptical of CSV's, but a customer requested one with his new WX 202. He waters the hell out his gardens and the pump rarely cycles on/off when the water is running. Fewer starts=longer life.

 

[Valveman]

Match the volume of the pump with the flow rate needed for that multi-head, multi-valve shower. Then the HP will be determined by the depth to water plus the pressure required for the shower.

I've helped with some showers that used 30 gpm at 90 psi. A 10 gpm pump would barely make it dribble.

 

[Reach4]

Thanks guys. Didn't know what gpm the 1 hp pump would be. Sounds like it'll be beneficial,

I don't see it as beneficial for water 100 ft down, but I am not a pro. I think the 3/4 is more in the sweet area of the curve. That 1 HP would be good if your water (not the pump) was down at 160 ft.

How about tank size? It's just an accumulator really. Seems that with a big enough pump and a big enough flow (thinking in terms of a double+ shower running) once the tank is drained and the pump takes over, tank size doesn't matter much.

If you don't use a CSV and you go with that 1 HP pump with only 80 ft to water, you would want about a 50 gallon or more precharged pressure tank.
.