Pumping Cost and Well Capacity
Definition
Pumping cost is the energy and upkeep cost of lifting groundwater from a well and pushing it through the irrigation system. It rises with total dynamic head (the vertical lift from the water level to the surface plus the pressure the system needs), with the volume pumped, with the price of electricity or diesel, and as pump efficiency falls. Well capacity is the rate a well can sustain, measured in gallons per minute (gpm); it caps how much water the farm can apply in its peak weeks and how many acres one well can carry. Lifting one acre-foot of water one foot takes about 1.024 kilowatt-hours at perfect efficiency, so the cost of groundwater is driven above all by how deep the water is and how efficient the pump is.
Why it matters
On a groundwater-dependent farm, the wells are part of the asset and the water level is part of the operating cost. Falling water tables raise the energy bill every year and eventually force deeper wells or new pumps, a capital cost that usually falls on the landowner. A well that cannot keep up in peak summer weeks limits the crop, whatever the farm's paper water rights say. Farmland Partners carries groundwater and irrigation improvements as separate depreciating assets and reviews groundwater's useful life against 'depletion levels of the aquifers.' An investor should know the depth, age, capacity and water-level history of each well, and whether the offering's projected costs assume today's lift or tomorrow's.
Common misconceptions
- •The well's depth is not the lift. Lift runs from the pumping water level, which drops while the well runs, plus the pressure the system needs.
- •Pumping cost is not fixed. It moves with water levels, power prices and pump wear.
- •A well's rated capacity is not its sustained capacity in a dry late summer.
- •Seasonal volume is not peak capacity. A farm can have enough water over the year and still run short in July.
- •Well replacement is not an operating cost the tenant always pays. Check who owns and replaces wells and pumps.
Technical details
Energy and cost per acre-foot (AltStreet illustration)
Energy per acre-foot = 1.024 kWh per foot of total dynamic head divided by overall pump efficiency.
300-foot head at 60% efficiency: about 512 kWh per acre-foot; at $0.20 per kWh, about $102 per acre-foot.
350-foot head at 60%: about 597 kWh and $119 per acre-foot.
At 3.5 acre-feet per acre, the 50-foot drop adds about $60 per acre per year.
Assumptions are illustrative; utility agricultural rates, demand charges and diesel pumps change the result.
Well capacity arithmetic
One gallon per minute running all year is about 1.61 acre-feet.
1,000 gpm for 150 days is about 663 acre-feet, about 189 acres at 3.5 acre-feet each.
Peak-week crop demand and pump downtime usually reduce the acres one well can safely carry.
USDA 2023 Irrigation and Water Management Survey
Energy for pumping well and surface water: $3.3 billion, $20,698 per farm reporting the expense.
Average well depth 241 feet; average depth to water at the start of the irrigation season 96 feet.
Farms using groundwater averaged 4.0 wells; 36% of wells had flow meters and 74% backflow prevention.
Average water applied: 1.5 acre-feet per acre.
How investors apply the term
Investors usually apply this term by tying the definition back to the controlling documents and then asking which cash flows, rights, restrictions, or valuation assumptions it changes. A useful review looks at the term alongside fees, leverage, liquidity, reporting frequency, and manager discretion rather than treating it as a standalone concept.
The practical diligence test is simple: identify who benefits if the assumption is wrong, who has control when conditions change, and what evidence the investor receives after closing. Terms that cannot be reconciled to documents, cash movements, and monitoring data should be treated as marketing shorthand until proven otherwise.
Frequently asked questions
- How much does it cost to pump an acre-foot of groundwater?
- It depends on lift, efficiency and power price. As an illustration, at a total dynamic head of 300 feet and 60% overall pumping plant efficiency, an acre-foot takes about 512 kWh; at $0.20 per kWh that is about $102 per acre-foot, or about $358 per acre for a crop using 3.5 acre-feet. These are AltStreet's assumptions; actual rates and efficiencies vary widely.
- What happens to pumping cost when the water table falls?
- It rises in proportion to the extra lift. In the same illustration, a 50-foot drop (head of 350 feet) raises energy to about 597 kWh and cost to about $119 per acre-foot, roughly $60 more per acre at 3.5 acre-feet. Deeper water can also reduce a well's yield or require lowering the pump or deepening the well.
- How many acres can one well irrigate?
- Divide the water it can deliver in the season by the crop's need. A 1,000 gpm well running continuously for 150 days delivers about 663 acre-feet, enough for about 189 acres at 3.5 acre-feet each, before allowing for downtime or system losses. Peak-week demand, not the seasonal total, often sets the limit.
- What do USDA's figures show about pumping nationally?
- USDA's 2023 Irrigation and Water Management Survey put energy for pumping well and surface water at $3.3 billion, $20,698 per farm reporting the expense; the average well was 241 feet deep with water 96 feet down at the start of the season; and only 36% of wells had flow meters.