How it works
Water runs down a pipe from a stream to the pump and picks up speed. A valve slams shut, and the moving water has nowhere to go: the pressure spike (the same "water hammer" that rattles your pipes when a tap shuts fast) pushes a little of it through a second valve and up the delivery pipe. The valve reopens and it starts again, 40 to 60 times a minute, all day and night. The water that isn't pumped flows back to the stream.
No motor, no fuel, no wiring. It doesn't make electricity; it saves it, by doing a job a well or transfer pump would otherwise do on your battery.
How much water
The rule Clemson Extension uses: delivered ≈ 0.6 × drive flow × fall ÷ lift.
| Drive flow | Fall | Lift | Delivered | A day |
|---|---|---|---|---|
| 12 gal/min | 6 ft | 20 ft | 2.2 gal/min | ~3,100 gal |
| 12 gal/min | 6 ft | 60 ft | 0.7 gal/min | ~1,000 gal |
| 5 gal/min | 5 ft | 50 ft | 0.3 gal/min | ~430 gal |
For scale: FEMA's figure is a gallon a person a day for drinking and basic hygiene. Even the smallest row covers a household's drinking water many times over, plus a garden or animals.
The 0.6 is a rough efficiency. The B.C. Ministry of Agriculture's table runs from about 85% when the lift is three times the fall down to about 55–60% when it's ten to twelve times. Lift up to roughly 10 feet for every foot of fall is realistic.
What your site needs
- A stream that runs all year, with more water than you want to pump. Only about one gallon in eight goes up the hill.
- Fall. About 5 feet for a dependable homemade pump. The pump sits below the source, at the stream's edge, so the extra water can drain back.
- A long, straight drive pipe, about 4–5 times as long as the fall, rigid so it doesn't absorb the hammer.
- Somewhere uphill for a tank. The pump fills it slowly and steadily; the tank handles the moments you open the tap.
Cost and upkeep
Clemson Extension (2019) put a homemade PVC pump at $150 to $200 in materials. The rubber valve parts wear and want replacing every couple of years. Otherwise it runs unattended for years.
No stream?
A ram pump needs moving water. For a well, the well pump page shows what powering one with solar and a battery takes.
Questions people ask
How much water does a ram pump deliver?
A small share of what goes through it, lifted much higher. Clemson Extension puts it at about one gallon pumped for every eight that pass through. Estimate it with delivered = 0.6 × drive flow × fall ÷ lift.
How high can a ram pump push water?
Up to about 10 feet of lift for every foot of fall. Efficiency drops as the lift grows compared with the fall.
Does a ram pump need electricity?
No. It runs on the momentum of the falling water alone, around the clock, which is why it saves the power an electric pump would draw.
How much does a ram pump cost?
Clemson Extension (2019) put a simple homemade PVC ram pump at $150 to $200 in materials.
Sources
- Homemade Hydraulic Ram Pump for Livestock Water (2019) Clemson Cooperative Extension
- Using a Hydraulic Ram to Pump Livestock Water (2006) B.C. Ministry of Agriculture
- Hydraulic ram pumps: introduction Low Impact
Every number on this page comes from these sources. Spotted something out of date? Tell me.
Get the exact setup
A few taps and you'll know exactly what to buy for your situation.