By David Spero – Code Green Prep
Many of us rely on wells for our water supply, and in such cases, we have an electric pump that lifts the water up and into a supply tank.
These pumps are usually long-lived and reliable, and draw little power (at least by present day standards where we have access to virtually unlimited electrical power at comparatively low cost).
But what happens in a future adverse scenario where first our power fails and then secondly our pump fails? The obvious answers are backups and spares, but there are also some design issues that should be considered well before any such problems occur.
Operating Electric Pumps When Electricity is Scarce
The first problem – power failing – will hopefully be addressed by your on-site power generation needs. One of the ‘good’ things about needing power for a water pump is that – assuming you have a reasonably sized holding tank above the well, the power your water pump needs can be time-shifted to those times of day when you have a surplus of (eg solar) power – use the power at those times to pump up water and to fill your above ground storage tank, and use the water from the storage tank at those times of day (eg night-time) when you have no free power.
Water pumps vary in terms of how much power they require, depending on the lifting height they need to bring the water, and the number of gallons per minute of water desired. Obviously, greater heights and greater gpm rates require more power. Fortunately, assuming moderate lifting heights and gpm requirements, you can get a lot of water from a pump that uses only 1000 or 2000 watts of power. From an energy management point of view, you would probably prefer to have a less powerful pump running for longer, than a more powerful pump running for a shorter time.
This also allows you to get good use from a well with a low replenishment rate. When specifying your well and water needs in the first place, you should give more importance to assured continuity of water supply at a low instantaneous flow rate but with sufficient total flow each day to meet your needs, rather than limiting yourself only to wells that can support rapid draws down of water via a high-capacity pump.
Chances are you can get the better part of a gallon of water lifted up your well and into your holding tank for every watt-hour of power – 1000 gallons per kWh if you prefer to think in those terms.
So the first problem – loss of utility sourced electricity – is hopefully not a huge problem (and see below for a discussion on hand pumps)….Continue reading at Code Green Prep: Water Wells and Planning for Problems