Community well, low flow solutions

[dtbingle]

Our house is on a community well and have a 3/4" copper pipe serving the house.
Source pressure is okay at 56-60 psi, but has rather low gpm numbers.
At 3.7 gpm of usage (2 showers running), source pressure sits at 48 psi (post-softener/filter @ 43psi) and is our minimum desired specs.


Once source pressure goes below 43 psi, the pressure post-softener and sediment filter just tanks.
At 3.7 gpm of usage, main pressure is at 48 psi and post-softener & filter is 43 psi - reasonable.
At 3.9 gpm of usage, main pressure is at 46 psi, but post-softener & filter is 37 psi - and continues to drastically drop with additional gpm.


What are my options to improve the flow with the current setup?

Looking at adding a 44 gallon pressure tank as a buffer. Then if 2 showers are running 3.7gpm for awhile, the tank would be equalized to 48 psi.
If a sink is used, toilet fill happens, short washer burst fill cycle, the tank should keep the pressure above 43 psi for a minute until the extra load turns off.
Do you think this would work? Is 44 gallons reasonable? Or should I be looking at like an 86 gallon tank?

 

[Valveman]

For a pressure tank to deliver any water the pressure must drop. And you hit the nail on the head for how a pressure tank will work to keep the pressure up when you said "for a minute". But even for that minute the pressure will be decreasing. Only a pump can boost pressure, not a tank. In the same space as you could fit a 44 gallon size pressure tank you could install a booster pump and a PK1Akit with a 4.5 gallon size pressure tank. In this way the pressure will stay as strong as you want, for as long as you want. A Cycle Stop Valve controlling a simple jet pump can deliver strong constant pressure for as many showers at a time as are needed, for as long a time as they are needed. From the details you have given I do not think you will be happy until the pressure is so strong that you barely even need soap in the shower, which is what a CSV will do. Lol!

 

[dtbingle]

I'm struggling to understand how the setup with a CSV, pump, and tank would help in my situation (maybe just misunderstanding how it works).
I thought the setup with the CSV was intended to vary (reduce) flow in order to maintain constant pressure, which in turn also reduces the number of well pump on/off cycles during an extended period of water usage. I thought the other part of this equation was that the well pump could produce enough gpm/psi to handle the load.

In my situation, the low flow from the shared well (about 100 houses) is due to undersized main pipes. If I set a CSV to 50 psi, my input from the shared well would only be about 3.5 gpm. This doesn't seem like it would be enough volume if it maintained that pressure.

Based on a 44 gal tank drawdown numbers, my source pressure/flow capacities, and fixture usage, I did a time plot of tank pressure accounting for the water deficit of source capacity minus fixture usage. If 2 showers have been running for awhile, it will equalize to 3.7gpm @ 47psi - aka the tank would also be at 47psi. Once adding in a 2 gpm load (deficit), for 5.7 gpm total, it would take just under 2 minutes to drain enough from the pressure tank below my 43 psi desired. My thought is that 2 minutes or less would be enough for total to refill, washer to complete it's short burst of filling, washing hands in sink, etc.

 

[Valveman]

A 44 gallon tank will give you 1/2 a GPM for every 1 PSI in pressure drop. An 86 gallon size tank will give you 1 gallon for every pound of drop in pressure. But for a tank to deliver any water the pressure must drop, which is what you are trying to prevent.

The reason you are only getting 3.5 GPM is because that is all the community water supply can push to you against that 47 PSI. If you install a pump to draw from the community water, it will pull the suction pressure down close to zero PSI. Pushing against Zero pressure instead of 47 PSI the community water can probably supply 10-15 GPM through the meter. With a PK1A kit controlling the pump it would deliver strong constant 60 PSI to the house instantly and for as long as you need it.

A pressure tank might give you an extra gallon or so as the pressure is decreasing. A booster pump with a CSV will give you all the gallons you need and increase the pressure, not decrease it.

 

[dtbingle]

Ah thanks for the explanation. That makes more sense. In my head I was still picturing that the community well is "pushing" against say a 50 psi and my community well would only be able to provide 3 gpm at that pressure. But from how you explained it, the well is essentially operating against a 0 psi when the pump is running and therefore can provide upwards of 6 gpm, and then the pump handles boosting the house side pressure up from there.

As far as noise, how loud are the pumps for interior installs?

 

[Valveman]

Now you got it. And yes pumps make noise. A little half horse like a J5SH won't be as noisy as a vacuum cleaner but more than most dish washers. There are ways to put it in an insulated box, which helps. There are also submersible pumps in a can that are silent, but not cheap. You could also fill a small cistern like 200 gallons with a float valve from the community water supply. Then a submersible pump in the small cistern will be very quiet for a booster pump.