River water pump system to multiple buildings

[Offgrid]

I am installing a submersible pump and pressure tank system in an off grid location on a river in Ontario.
There are four buildings that will need water and they are at different elevations and spread out.
There is a shed by the river and another on an upper tier about 200 feet above the location of the pump intake in the river. Two of the lodging buildings are on the upper tier and two are below. My question is, should I put the tank and filters (25 micron and 5 micron ) in the lower building and pump to the upper building and then split to the lodging areas or put the tank and filters in the upper building.
Sorry if this sounds confusing, anyone that can give me some advise on location and sizing and equipment would be appreciated. There is abundant solar power and back up generator power available and cost is not a problem. Thanks

 

[LLigetfa]

With 200 feet of head, everything at the bottom would need to handle twice the pressure but if it were up top you would need two pipes. You might want to consider using a second pump for the hilltop.

 

[Sponsor]

 

[Reach4]

There is a shed by the river and another on an upper tier about 200 feet above the location of the pump intake in the river. Two of the lodging buildings are on the upper tier and two are below.

How much below?

When you say 200 ft above, are you referring to altitude, or pipe distance?

Also, what will be more important for your calculations is the altitude from the river surface at low water, rather than the rise above the intake. The intake may well be shallow enough to make that difference small.

 

[Offgrid]

The water depth at the point where the intake will be is approximately 40 feet and another 60 feet to the top of the hill for a total of 100 feet of lift.
The distance is around 200 feet to the shed.

 

[LLigetfa]

The water depth at the point where the intake will be is approximately 40 feet and another 60 feet to the top of the hill for a total of 100 feet of lift.

Lift is only measured from the water's surface so the first 40 feet doesn't count. It is .43 PSI per foot of rise.

 

[Reach4]

I would tend to want put the pressure tank and pressure switch at the top. Cartridge filters go after the pressure switch and tanks. If you need filtering before the pressure tank and switch, special considerations are needed to prevent a clogged filter from deadheading the pump.

Will you chlorinate or do other water treatment beyond sediment filtering?

It is important to have vacuum relief valves.

For the cartridge filters, have at least two sets, and have independent bypasses around each set. That way you can keep the water in service while changing cartridges, and you have some redundancy in the case of a failure in one of the filters.

 

[Offgrid]

I will be using a uv light system and no chlorination also a three part filtration system in cabins for drinking water. The dual cartridge system and vacuum relief valves are good ideas I will incorporate them. Thanks for every ones input.
As a follow up I went on Google earth pro and did the elevations for the river to pump house on the upper level. I found I vastly over estimated the rise up the hill, it is 50 feet.

 

[LLigetfa]

There is 21.5 PSI drop on 50 feet of elevation, not counting friction loss on the length of pipe. Assuming the lower cabins are above the river water level, the PSI difference will be less than that. It would not require higher pressure tolerant water treatment to locate them at the lower level.

 

[Valveman]

The pressure switch and pressure tank need to be together. If you put them at the bottom of the hill by the pump you would need a 60/80 setting to make up for the 21 PSI loss in 50' of lift. But if you put the pressure tank/pressure switch at the top of the hill it will only need to be set at 40/60. although the pump will still be working at 60/80.

 

[Offgrid]

Thanks for your reply. Anyone know offhand whats the biggest or best size pressure tank to supply four locations ?

 

[LLigetfa]

Trying to size the tank for four locations will always be a compromise as it adds 4X variability. I would opt for a sub that has the impeller shaft carried by main bearings rather than each impeller floated to reduce current draw when held back by a CSV and not worry about tank size. ISTR @valveman mention that Grundfos pumps have lower current draw at the higher pressures so should be a good fit for solar.

 

[Reach4]

Thanks for your reply. Anyone know offhand whats the biggest or best size pressure tank to supply four locations ?

Four apartments with 2 bathrooms etc each? "119 gallons" is the biggest usually used. This would pair with a 20 gpm or 25 gpm pump I think.

Or are these lodges each multi-unit things?

 

[Valveman]

A 119 gallon size tank only holds about 30 gallons of water. Get a couple of those expensive tanks and you will have 60 gallons of water to use before the pump comes on. Then you can start the generator and put another 60 gallons is the tanks.

If you are running off of solar, you would actually be storing energy in those pressure tanks. You could store energy in a couple extra batteries instead, and not need nearly as large a pressure tank.

A CSV is great for multi-use systems. It would maintain a constant 50 PSI pressure for the water users, instead of the pressure continually fluctuating between 40 and 60. With a CSV a 44 gallon tank would be plenty, but you would need extra batteries.

 

[Offgrid]

Thanks again, there are four separate buildings with a washroom and kitchen in each. The solar system will handle any pump load as well as the rest of the power needs and has a automatic diesel generator tie in.

 

[Reach4]

I would be thinking a 20 gpm 1 hp pump, unless you had some added irrigation or fire sprinkler loads. 15 gpm 3/4 hp might be enough even.

I would use pump with 3-wire motor with a run capacitor in the control box to reduce power consumption

 

[Valveman]

Lodges and multiple dwellings are like a hotel, they cause the pump to cycle a lot even when large pressure tanks are used. You can do this whole place and not have cycling if you use a CSV1A and about a 44 gallon size tank. Then with a pump that has good amp draw characteristics like a Grundfos 16S10-10, it will draw 1HP load when using 20 GPM, but when only using 1-2 GPM the CSV will make it only draw 1/2HP load. The pump will run longer to supply the demands, so it will use slightly more energy. However, the lack of cycling with a CSV will reduce the number of high inrush starts, make the pump last longer, and saves lots of money and space by using a much smaller pressure tank. Plus the people in the buildings will have even more constant pressure than if it was supplied by a city water system.

 

[Offgrid]

Thanks to all for the good advice.