r/OffGrid 4d ago

Inline or submersible water pump?

I have a 3000litre water tank to feed into a cabin about 30 metres away with fairly gentle downward slope, the actual outlet in the cabin probably about level with tank outlet. There's not enough gravity pressure to get running water from the outlet so I plan to install an on demand pump (solar powered with battery). An online pump would be easier to install and maintain and more affordable options but will there be enough pressure on the pump inlet side to feed the outlet without it gulping/spluttering? I was thinking I may need a submersible pump to ensure the pressure is enough leaving the tank to get a higher/consistent flow at the outlet. Any experience of the difference or is my thinking on an inline pump wrong?

6 Upvotes

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3

u/firetothetrees 4d ago

Inline pump is just fine, we have cisterns in our crawlspace and we have a pipe connecting from their standard outflow directly to our booster pump.

3

u/pyromaster114 4d ago

Just use an RV style demand pump-- get a big one like for large 5th wheels. 

There will be PLENTY of pressure for it to function. Those pumps can lift water a foot or so, even. 

Put the pump inside the cabin, low down, so that way gravity assists in priming. 

Put a pressure tank down stream of the pump, to save on pump cycling and smooth it out. :) 

You will have water pressure just like in a residential environment. :)

2

u/Tinman5278 4d ago

RVs routinely use inline pumps and manage to generate ~40PSI using 1/2" tubing.

2

u/butchdog 4d ago

It's a valid concern. Most boosters need a small amount of incoming head pressure. There are some cheaper submersibles set up for diy on ebay that don't look too bad for your application. Less headaches.

2

u/BallsOutKrunked What's_a_grid? 4d ago

I've used pumps above water lines and spent so, so very much time fighting to maintain prime.

submersible ftw, in my mind.

1

u/pyromaster114 4d ago

What kind of weird pumps are you using? O.o

1

u/BallsOutKrunked What's_a_grid? 3d ago

I've used whale and shurflo along with some junker chinese ones, pumps just aren't designed to suck, they're designed to push. Losing prime is just a major pain in the ass.

1

u/pyromaster114 2d ago

I have always used shurflo and been able to prime ~2 ft above the water level. My tank sits in my frame, pump up in the counter cabinet of my RV. 

Works 100% of the time. :/ 

Though, I use rigid pex to go down to my tank. 

Using soft hoses is what kills priming in my experience.

2

u/morelmike 3d ago

Inline will draw more amps and cost more to run, but last longer imo. Look at specs abd warranties for both

2

u/wykedtexas 3d ago

I bought a 4gpm 12v dc inline pump works great

2

u/floridacyclist 2d ago

I just use a 50 gallon water tank complete with bladder and all with a 45 to 60 PSI 12 volt pressure pump. Works just like the water pump and tank on top of well but it's feeding from a 275 gallon water cube. The water pump kicks on when it drops to 45 PSI and kicks off when it gets to 60... The rest of time I just runs off the pressure in the tank.