Need to increase water pressure to go another .25 miles

[Cabin Fever]

Good evening everyone!

Here's the gist of my issue; bought a cabin and ran a 100 psi 1.5in poly pipe 3,800 feet from meter (not regulated, main line pressure 56lbs) to the cabin and after 1/2 mile the psi is only 6lbs. We have a frost free there that we tested. Elevation increase is 117 feet to that point. We need to reach the cabin which is another 38 feet increase in elevation .2 miles away and have sufficient pressure to run shower, toilet and 2 sinks. 1/2 mile location requires pump to be ran on solar with battery storage. One suggestion I've heard is installing a cistern with well pump, I believe there may be something simpler....? Inline pump with pressure tank(s) maybe. One concern is 6psi not being able to supply enough to a pump.

Thank you for any suggestions including type of pump, possible pressure tanks and solar panel requirements.

 

[wpns]

155 feet elevation change is 67PSI, so your water flow is going to be zero without any intermediate pumps. How did you plan this? Is the pipe NSF-Rated? Black poly tubing for potable water looks to be of interest.

Depends on your various available locations and if there's power available, you could put booster pumps at the meter, the 'midpoint' where you have the frost-free hydrant, and/or the cabin (or somewhere else?). Is this going to be used year-round, or just occasionally? How many people, and what's your expected water consumption? What climate? I assume since you have a frost-free and are in CO that you are subject to freezing. Is the poly pipe buried below the frost line for the whole 3/4 mile? Is it well bedded in sand or soft soil the whole way? I have enough problems with it used for irrigation systems that your description leaves me with goose bumps.

Personally, given the length and fragility of your supply, I'd put in a cistern with a float switch (and rain water catchment), an ozone system from Triple-O, and a pressure pump at the 'midpoint', but that's the kind of system I'm used to.

 

[Valveman]

The 100 PSI pipe is going to be your limiting factor. As was said you need another 67 PSI at the bottom to have the pressure up top that you need, However, with 56 PSI coming in and adding 67 PSI boost you will be at 123 PSI, which is more than the rating of your pipe. It is best to boost pressure from the beginning but a booster pump about 1/2 way up the hill would decrease the pressure on the pipe. Would look something like this.

 

[Cabin Fever]

Thank you!

Originally the guy we had helping us was telling me only 85 feet of change and we thought the meter could be turned up over 65 with a waiver as other surrounding neighbors have done this. Meter up to 70 would have put us at 33 at the cabin. We have the Black poly tubing for potable water that's rated at 100psi buried 3 feet bedded in soft soil the whole way. Will be used year round. Hunting cabin and airbnb. Yes Colorado and cold in winter. Meter elevation 7335, cabin 7490. Sleeps 6 to 8 people. Zook Cabin Rancher Model.

Valveman, you're recommending boosting at the meter and half way?

 

[Valveman]

If you boost from the meter the pressures will be over 100 PSI. Because of the 100psi pipe you will need to place the booster further up the hill to spilt the pressure up.

 

[MicEd69]

As other's have commented, the elevation difference will require 67 psi to overcome. However, if you install a system to maintain 100 psi at the meter, when flow is required the pressure at your cabin will be 33 psi, or 76 feet of water column. The pressure drop of 15 gpm of water through 100 feet of poly pipe is 2.1 feet of water column. So, a pipe length of 3,800 feet flowing 15 gpm will have a pressure drop of 79.8 feet of water column. That is close to the pressure you would have, so I would expect that should you install a 100-psi controlled pumping system at the meter, you could expect 12-14 gpm at you cabin, depending on fittings in the line and fixtures.

 

[Valveman]

Also, bust pressure of pipe is 2 to 5 times the rated pressure. You have some cushion if you used two hose clamps on each barb fitting.

 

[wpns]

I missed the query in the original post about solar power systems, it's pretty straightforward, but depends on a lot of factors, like solar insolation at that location, number of people->water consumption->power requirements->panels, batteries, inverters.

8 people is 800GPD(*), but seriously 8 people with shower, toilet and 2 sinks?
Colorado | TurbineGenerator says CO is 4.44 peak solar hours
Valveman, what's the power consumption of that booster system (in watthours per gallon?)

(*) Wasteful NA standard, but AirBnB is likely to hit that, IMHO.

TPP Tankless Pressure Pump™ System 1HP looks like overkill in terms of GPD, I'l call them and see if there's a smaller system that would work for you.

 

[Valveman]

Valveman, what's the power consumption of that booster system (in watthours per gallon?)


TPP Tankless Pressure Pump™ System 1HP looks like overkill in terms of GPD, I'l call them and see if there's a smaller system that would work for

It depends on what size booster pump is needed. But to do the 117 PSI needed it would take 2 or 3 of the pumps you mentioned placed in different locations going up the hill. The higher the hill the more "watts" are needed.

 

[MicEd69]

It depends on what size booster pump is needed. But to do the 117 PSI needed it would take 2 or 3 of the pumps you mentioned placed in different locations going up the hill. The higher the hill the more "watts" are needed.

I'm a little confused by your comment that more than one pump would be required. The pump curve of the pump wpns showed indicates that pump can deliver around 45 psi at a flow rate of 15 gpm. And based on the analysis I did above, that pump would deliver 15 gpm at the cabin if placed at the 56 psi source. Unless some controls are included, the pump at lower flow rates and at shutoff would pressure the piping to 110 psi, but as you have stated, that is well below the burst pressure and I would not be afraid of operating the piping at that pressure on a daily basis. And the 56 psi supply pressure will also vary a bit anyway as well.

I seriously doubt they will ever use 15 gpm for any appreciable amount of time if ever, but that is what would theoretically be available with the original supply pressure, this pump, and their piping layout.

So, why do you think more than one pump would be required, and why would the power requirement increase as one moves up the hill? The pump is boosting the pressure of the water and if there were more pumps along the line, the flowrate would be exactly the same, so the power requirements of each pump would depend on the head each pump would be required to produce. So, if there were two pumps, and the lower pump produced more head than the higher pump, the higher pump would require less power. Or am I not understanding this issue correctly?

I do have concerns about the solar power available for this location as wpns indicated.

 

[Valveman]

I would not count on there being 56 PSI at the meter when you start drawing with a pump. I would figure maybe 20-30 PSI coming in. To boost 20 PSI to 117 PSI it would take 2 of those 1HP pumps in the right locations. It would take a 2HP pump to do this with only 1 pump. If you figure "best case scenario" one of those pumps might work, but rarely do I get a "best case".

 

[MicEd69]

I would not count on there being 56 PSI at the meter when you start drawing with a pump. I would figure maybe 20-30 PSI coming in. To boost 20 PSI to 117 PSI it would take 2 of those 1HP pumps in the right locations. It would take a 2HP pump to do this with only 1 pump. If you figure "best case scenario" one of those pumps might work, but rarely do I get a "best case".

OK, I understand your thinking. I was assuming that this was off a city water supply which would supply a pretty constant pressure. After all, the draw will usually only be 3 to 6 gpm.

 

[wpns]

He has 6 PSI and needs to go up another 38 feet plus maybe 25-50 PSI. Not sure what his flow rate is at the 6PSI point, but worst case that could fill a cistern at 1GPM

 

[MicEd69]

He has 6 PSI and needs to go up another 38 feet plus maybe 25-50 PSI. Not sure what his flow rate is at the 6PSI point, but worst case that could fill a cistern at 1GPM

By installing the pump suggested at the bottom of the hill, and assuming the water supply at the bottom of the hill remains about 50 PSI, he will have 25 to 30 psi at 12-14 gpm.

 

[wpns]

By installing the pump suggested at the bottom of the hill, and assuming the water supply at the bottom of the hill remains about 50 PSI, he will have 25 to 30 psi at 12-14 gpm.

And he'll be (further?) pushing his luck on the pressure rating on the pipe. Personally I like the solar powered pump at the 3/4-of-the-way point, but if there's power available at the meter, a controlled booster at that point isn't an awful solution, and thousands of dollars less. IMHO he needs a leak detector or process, if something springs a non-catastrophic leak (or a complete blowout when he's not there), he's going to have a big water bill to contend with in addition to finding and repairing the leak.

 

[MicEd69]

I guess the issue is do you want two places for a "system" that you need to maintain or put it all in one location. Valveman is concerned about the supply location maintaining the current pressure and is suggesting 2 or 3 pumps. You are concerned about running a 100 psig pipe at 110 psig during worst case operation.

A length of pipe is not at all like a motor or some mechanical machine. Running a mechanical piece of equipment at 110% is not the best. But there are factors of safety on the pressure rating of pipe that are not going to over stress the pipe if operated at 10% over the pipe rating for the periods of time that water is being used. If the pressure was 110 psig continuously, like at the bottom of a water tower 255 feet high, that would be a problem.