A rope pump is a continuous loop of rope carrying rubber or plastic washers about 1 m apart up through a PVC pipe that dips into the well, turned by a wheel and crank at the top; it suits most community wells because it is built from local materials and mended by changing a rope or a washer. Lifting 10-15 L/min through 40 m takes 65-98 W of hydraulic power before any friction, so at great depth the flow you get depends on how hard people can turn the wheel.
Part of Deep Wells
A rope pump is a hand-cranked water lift in which washers fixed on a rope act as moving pistons inside a pipe. It has no valves, no metal pump barrel and few parts that wear.
The Washers Push A Column Of Water Up The Pipe
The washers fit the pipe closely and are carried up through it on the rope; the water between them is pushed up and out of the top, and the loop returns down the well. Turning the wheel pulls the rope continuously, so the water comes in a steady stream. The Deep Wells guide describes washers of rubber or plastic spaced 1 m apart on the rope, running through a PVC pipe submerged in the well, and lists the pump as easy to build and easy to maintain, with a depth of 40 m and more at 10-15 L/min.
The Lift Is Limited By Power, Not By Pipe
Lifting water takes power P = ρ × g × Q × H: density 1,000 kg/m³, gravity 9.81 m/s², flow Q in m³/s, and lift H in m.
Working in SI units: Q = 10 L/min = 10 ÷ 1,000 ÷ 60 = 1.667×10⁻⁴ m³/s, so each metre of lift takes 1,000 × 9.81 × 1.667×10⁻⁴ = 1.635 W. At 15 L/min (2.5×10⁻⁴ m³/s) each metre takes 2.45 W.
| Lift | 10 L/min | 15 L/min |
|---|---|---|
| 10 m | 16 W | 25 W |
| 20 m | 33 W | 49 W |
| 40 m | 65 W | 98 W |
These figures are the hydraulic minimum, before friction in the rope, wheel and washers, which add more. A person turning a crank for a long spell can sustain well under 100 W of useful output (an order of magnitude recalled from work physiology, not measured here), and less from arms than from legs. At 40 m the Deep Wells guide’s 10-15 L/min is therefore at or beyond what one person can sustain; expect lower flow at that depth, or two people on the wheel, and relatively easy work at 10-20 m.
Rope tension. The rope also carries the weight of the water column in the pipe. For a pipe of 25 mm bore (area π ÷ 4 × 0.025² = 4.91×10⁻⁴ m²) at 40 m, the column is 1,000 × 4.91×10⁻⁴ × 40 = 19.6 kg, a force of 19.6 × 9.81 = 193 N. For the flow, the rope speed is v = Q ÷ A = 1.667×10⁻⁴ ÷ 4.91×10⁻⁴ = 0.34 m/s at 10 L/min, with perfect seals; leaky washers need more speed for the same flow.
What You Need
- PVC pipe — long enough to reach below the lowest water level, in one piece or solvent-cemented sections
- A rope — for the loop; a synthetic rope resists rot better than natural fibre (Rope Making)
- Washers — rubber or plastic discs, a snug fit in the pipe, fixed on the rope about 1 m apart
- A wheel and crank — a wooden wheel or a salvaged rim, on an axle in a frame
- A guide at the bottom — a funnel or block that steers the washers into the pipe
- A cover and apron — to close the well and carry the frame (Sanitary Apron)
Method: Build The Loop, Fit The Guide, Seal The Head
Step 1: Make the rope loop with a splice. Knots catch in the pipe; use a long splice and keep the diameter even.
Step 2: Fix the washers about 1 m apart on the rope, so that each fits the pipe snugly.
Step 3: Fit the pipe and guide. Hang the pipe in the well with its foot well below the lowest water level, and set the guide at the foot to take the washers in without catching.
Step 4: Mount the wheel above the pipe, in line with it, with enough wrap on the wheel that the rope does not slip.
Step 5: Tension the loop so that it grips the wheel but is not stretched tight. New rope stretches: re-tension after the first days.
Step 6: Close the head. The rope and pipe pass through a cover so that nothing but water leaves the well. Shield the descending rope with a tube so that hands, mud and insects cannot ride the rope down into the water.
Common Mistakes
- Washers too loose. Water slips back and the flow is poor.
- Too much tension. The rope wears at the wheel and the bearings.
- An open head. The descending rope carries dirt straight into the well.
- Expecting full flow from great depth. Check the power table above.
Safety
Pinch points and a moving rope
The rope runs onto the wheel with enough force to drag fingers, hair and clothing; keep hands clear of the rope-and-wheel contact point and add a guard. Keep children away while pumping. Do not look down the pipe or well while the rope is moving.
What’s Next
- Learn next: Well Protection — sealing the head
- Combine with: Pump Selection — comparing the options