Underground to indoor tank pump... help choose

[containercabin]

Hey,

I plan on having a 350g cistern underground that will feed my 18 gallon indoor tank. From my estimates - the head lift will be about 15ft.....

I have seen Don use a bilge pump but those are DC and I have no desire to figure out the wiring. The only pump I found that can lift so high - http://www.amazon.com/gp/product/B000X05G1A/ref=ox_sc_sfl_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

This pump is relatively cheap for a 1/4hp sump pump but in comparison to Don's Bilge it is 4 times the cost.

Anyone has advice on a cheaper alternative?

[rick91351]

Is a sump pump safe for potable water?  Or is this potable water?  How are you going to work the switching?

[containercabin]

this pump is safe. rain water. regular switch...

Anyone with pump rec?

[JRR]

No recommendations but just some comments:

If you had a pump that had "perfect suction", or a pump that could create a "perfect vacuum" on its suction side ... it could still only lift 29ft of water ... and that's at  sea level...its a matter of the physics that Mother Nature gives us.  Practically, we must reduce that figure by half or more .... and consider that no matter how good the pump, we should not expect it to lift more than 12 to 14 feet of water on the suction side.  Now the output side is a different matter ... it can be almost any figure.

Quite often, manufacturers of small pumps will speak of "total head" ... that means the suction side (or lift) measured in feet ... added to the output (or pressure side) in feet ... for a total head in feet, or sometimes in PSI.  So be  careful of this practice.

[SouthernTier]

JRR:  You are correct (*) about the limitations of lifting by suction.  However, you can *push* water as high as you want.  It seems like CC is looking at pushing the water, so no limitations, there.

* correct, except the part about output being almost any figure.  The faster you pump, the more pressure drop through the line, and thus less static head you will be able to handle. Total head is static head + pressure drop through the line due to friction + output pressure.

[MountainDon]

Don't let DC wiring scare you off. It is different from AC but should not be a big worry.

The major disadvantage for DC can be the wire size needed for high amp loads and low voltage in DC. (12 VDC is considered low). But your cabin is small enough that this should present no problem. Min wire size (AWG) can be calculated with many online calcs or just ask here, giving distance from batt to pump, amperage and voltage.  On the other hand messing around with water and submersed pumps and wires is not nearly as potentially dangerous as doing the same with 120 Volts (Ac or DC).

You do need to use a proper switch rated for DC, but those are available.

Using DC does increase the system complexity slightly but should not be overwhelming. I use plugs and outlets that do not permit making a mistake by trying to plug a DC into an AC and vice versa.


As you have found, DC pumps can be had cheaper than most AC. That was one reason I went with a manual hand pump in the beginning. Later I found the less expensive Rule inline pumps, which do seem to perform well. Just be careful to select the right pump for the distance the water must be pushed. I can vouch for the fact that the pump performance is diminished when it has to push from a near empty tank as compared to a more full tank.

[MountainDon]

Bilge may be a dirty sounding word, but unless we were planning on drinking real bilge water should be no issues.    Any submersible pump can be sanitized in a bleach solution before being placed permanently in the water cistern. The electrics are well sealed so I doubt there is any problem with lubricants, if any, seeping into the water.

[JRR]

JRR: ......  However, you can *push* water as high as you want. ....

* correct, except the part about output being almost any figure. ....

Gee, aren't those two comments about the same?  I was saying the output pressure can be anything the pumping equipment can handle ... Or, "you can push as high as you want".