Move water uphill with no power.
See if a ram pump works at your site.
A hydraulic ram pump uses the fall of a creek or spring to push some of that water uphill. It needs no fuel and no electricity. Put your numbers in the calculator and see what you get.
Check my siteSee pipe specsBuilt and tested on a creek-fed ram pump that has run for 3 years on our own off-grid garden.
Check your site
Enter your flow, fall and lift. See gallons per day and how much water you need.
Open the calculator →Specs and start-up
Pipe sizes, flow ranges, drive pipe length, start-up steps and the intake.
See the specs →Fix-it and FAQ
What your pump does, the causes to check in order, and common questions.
Open the fix-it chart →Build it in 3D
Turn, zoom and pull apart our 1-1/2 in ram pump and the full creek system.
Open the 3D model →Plans and kit
Build plans for 8 sizes, $19 each. Our 1-1/2 in plan is field-built. The other 7 are not field-built yet.
See the plans →Ram pump site calculator
Move each slider, or type a number. The picture and the results change as you move. Each check shows a word and a symbol, so you do not need to read colors.
Bucket test: fill a 5 gallon bucket from the source. Gallons divided by minutes = gpm.
Measure from the top of the water, not from the pipe inlet.
Measure from the pump, not from the creek.
An open pipe that stands up from the drive line. The shock wave stops there, so the drive pipe length is measured from the standpipe to the ram.
Water in an open standpipe rises to the source level, not higher. The extra height catches the surge each time the waste valve shuts.
Use rigid pipe only. Run it level or downhill, with no high spots.
Formula: water out = pump factor x water in x fall / (lift + delivery pipe friction). Results are estimates, not an engineering design.
The ram trades a lot of water falling a short way for a little water lifted a long way. Each 1 ft of water height adds 0.433 psi. With a standpipe, the usable fall is the water level in the standpipe down to the ram. Friction in the supply line pulls that level down as the flow goes up.
How much water do you need?
Enter what you water each day. The calculator above compares this need with what the pump gives you. Use the high end in hot weather.
Garden: 1 in of water on 1 square foot is 0.62 gallons (University of Minnesota Extension, Purdue). Animals: daily use per head from USDA NRCS (MWPS-14 table): beef 8 to 12, horse 12, goat 2 to 4, 100 layers 9. We use the high end.
Specs by drive pipe size
Typical homemade ram flow rates at 5 ft of fall and 25 ft of lift, with Schedule 40 PVC drive pipe. Source: Clemson University LGP 1017, Table 3 and the Calvert drive pipe rule.
| Drive pipe | Delivery pipe | Water in (min to max) | Water out (at min to max) | Drive pipe length (min to max) |
|---|
Second rule (based on fall, a common rule of thumb in build guides): drive pipe = 6 x fall for 3 to 15 ft of fall, 4 x fall for 16 to 25 ft, and 3 x fall for 26 to 50 ft. Try to meet both rules.
Words used on this site
Open
- Drive pipe: the rigid pipe from the water source down to the ram.
- Waste valve: the valve that slams shut many times each minute and makes the pump work.
- Air chamber: a sealed pipe with air in it. It smooths each push of water.
- Snifter valve: a very small hole or valve that lets a little air into the air chamber on each beat.
- Calvert rule: a rule from N. G. Calvert. Drive pipe length is 150 to 1,000 times the pipe diameter.
- Fall rule: a common rule of thumb in build guides. Drive pipe length is 3 to 6 times the fall.
- Schedule 40: a standard wall thickness for PVC pipe.
- gpm: gallons per minute.
- Standpipe: an open pipe that stands up from the drive line. The shock wave stops at its open top.
- Supply line: the pipe from the intake to the standpipe.
- Suction lift: lifting water by pulling on it. Air pressure limits it to about 33.9 ft at sea level.
- psi: pounds per square inch, a unit of water pressure.
- Back pressure: the pressure that the water in the delivery pipe pushes back with. The ram needs about 10 psi of it to run.
- Lift to fall: lift divided by fall. For example, 40 ft of lift and 5 ft of fall is 8 to 1.
- 0.433 psi per foot: the pressure that each foot of water height adds.
- PR160: PVC pipe rated for 160 psi of pressure.
Start-up steps
From the Clemson design. Most "it does not work" problems start here.
- Put the drive pipe inlet at least 6 in below the water surface. Put a screen on it. This stops air from going into the pipe.
- Connect the ram to the drive pipe.
- Close the delivery valve.
- Open the drive pipe valve so water flows to the ram.
- Push the waste valve flapper down by hand 20 to 30 times. The pump then starts to run by itself.
- If the pump does not start after 70 pushes, stop. Something in the system is wrong. Use the fix-it chart.
- When the pump runs, open the delivery valve slowly. Watch the gauge and hold about 10 psi.
A normal ram beats about 40 to 90 times per minute (Clemson). Practical Action gives 30 to 100. If the tank outlet is less than 23 ft above the ram, partly close the delivery valve to keep about 10 psi of back pressure.
Fix-it chart
Find what your pump does. Check the causes in order. To see how much to trust each source, open Sources and proof at the bottom of the page.
| What you see | Check these causes | Source |
|---|---|---|
| Pump will not start | Wrong waste valve. It must be metal and close by the force of the water alone: a free-swinging brass swing check, or a brass spring check with the spring taken out, mounted upright with the arrow pointing down. A PVC check, or a check with its spring left in, will not work. Not enough fall. Air still in the system. A flexible hose used as the drive pipe. | Clemson; our own pump (spring check) |
| Runs a few beats, then stops | Drive pipe too long or too short for the pump size. Delivery valve not closed during start-up. | Clemson |
| Pulses very hard, then stops | No air cushion in the air chamber: a missing or worn inner tube, or a cracked chamber. | Clemson |
| Output drops slowly over weeks | Water slowly takes up the air in the chamber. Drain the chamber, or clean or fit a snifter valve. | Practical Action, Clemson |
| Stopped after running fine | Clogged intake screen. Low creek flow lets air in. Debris holds the waste valve open. Air lock in the drive pipe. | Clemson intake guidance |
| Water spills out of the standpipe top | The standpipe top is lower than the source water level, or less than 1 ft above it. Raise the standpipe. | Build It Solar |
| Beats very slowly on a long run | The drive pipe is too long. Add a standpipe at the maximum drive pipe length from the ram, or move the standpipe closer. | Build It Solar |
| Runs, then sucks air (with a standpipe) | The supply line cannot keep up, so the level in the standpipe drops to the drive pipe inlet. Use a larger supply line or less drive flow. | Our own math (supply line friction) |
| Stops after a few beats (with a standpipe) | The standpipe is too close to the ram, so the drive pipe is now too short. Check the drive pipe length range. | Clemson (drive pipe too short) |
| Will not run with a garden hose test | A hose feed does not make the shock wave. Test with the drive pipe from a bucket at least 5 ft above the ram. | Clemson |
Set up the intake right
Open
Many "it stopped" problems start at the intake. Air and debris in the drive pipe stop the pump.
Keep it deep
Put the drive pipe inlet at least 6 in below the water surface. A shallow inlet can pull in air. (Clemson)
Screen it
Use a screen ball or globe of 12 in or more across on the inlet. This stops debris and a vortex that pulls in air. (Clemson)
No high spots
Run the drive pipe level or downhill all the way. A high spot traps air and stops the shock wave. (Clemson)
Pump not running right? Open the fix-it chart →
Questions people ask
How high can a ram pump push water?
Clemson says to plan on about 10 ft of lift for each 1 ft of fall. That is a planning rule, not a hard limit. A ram can push higher, but less water comes out as the lift goes up. Most sites work best at 6 to 12 ft of lift per 1 ft of fall. Past about 20 to 1, so little water comes out that the calculator marks it FAIL. Check your numbers in the calculator.
How much of the water goes back to the creek?
Most of it. Clemson says a ram pumps about 1 gallon for every 8 gallons that pass through it. The rest flows out of the waste valve and back to the stream.
How fast should it beat?
Clemson gives about 40 to 90 beats per minute. Practical Action gives 30 to 100. A longer drive pipe gives a slower, stronger beat.
Can I get water pressure at my house?
The ram fills a tank. The tank height then gives the pressure. Each 1 ft of height gives about 0.433 psi, so a tank 50 ft above a tap gives about 22 psi.
Can I start it with a siphon?
It can work, but only if the drive pipe stays full and free of air. A drive pipe that runs uphill at any point traps air and stops the pump.
Is the water safe to drink?
A ram pump does not clean water. It moves creek water as it is. Test the water before you drink it. For drinking water, use lead-free brass parts only (US EPA).
Is there a 33 ft limit on lift?
Not for a ram pump. The 33 ft limit is for pumps that pull water up by suction. Air pressure at sea level can hold up a column of water about 33.9 ft tall, and suction pumps stop at about 25 ft in practice. A ram pump does not pull. It pushes water up from below, so this limit does not apply to its lift. A USDA NRCS note describes a large 4 in ram that fills a tank 245 ft above the pump. A lift that high needs a big fall too: it still follows the lift-to-fall rule above. The suction limit does still apply to any part of your drive or supply line that rises above the source water level, like a siphon.
What does a standpipe do?
It gives the shock wave an open place to stop. The ram then works as if the source were at the standpipe. Water in an open standpipe settles at the source water level, minus the friction loss in the supply line. That is why the standpipe top must stand above the source level.
What about winter?
Water that freezes in the pipes or the air chamber can crack them. Build an insulated cover for year-round use, or drain the system before a hard freeze.
Build your pump
See the whole water system first. Tap any part to open it and pull it apart. This model follows our own 1-1/2 in ram pump, the one that has run for 3 years on our creek. Drag to turn it, or use the buttons.
Zoom: use the + and − buttons, the mouse wheel, or pinch with 2 fingers on a phone. Tap a part in the list and the view zooms right to it. Switch "Drag to" to Move, or hold Shift, to slide the view. Tap any part to open it, then use "Pull apart" to see every piece. Change the drive pipe size to see the pump at that size. Colors: white is PVC, gold is brass, gray is steel, brown is wood, blue is water, dark blue is hose. Patterns show the same thing, so you do not need color: brass is striped, steel is dotted, wood is lined, water is wavy, hose is cross-hatched, soil is speckled.
Full system parts
| # | Part | Job |
|---|
How our 1-1/2 in pump is built: all PVC pipe and fittings are Schedule 40, joined with maximum-strength PVC cement. The valves, unions, pipe cock and gauge are threaded, not glued.
Want the build plans? See the plans →
Build plans
Build plans for 8 drive pipe sizes. Our 1-1/2 in plan comes from the pump we built and run. The other sizes are designed from that build and from published university and agency sources, and every page says so. Not sure of your size? Use the free calculator.
Build plans: 1-1/2 in ram (PDF)
- 10-page PDF, with how a ram pump works in plain words
- Full parts list, numbered to match the free 3D builder
- 18 build steps, from the pump to the creek-side setup
- Photos of our working pump
- Start-up card, monthly air care and a fix-it chart
- Water-output math with a worked example
$19 one-time, digital download
Buy the plans: $19Checkout is on Gumroad. Results depend on your water flow, fall and lift.
All sizes bundle (8 PDFs): $99
- All 8 plans, 3/4 in to 4 in
- 1 field-built (1-1/2 in) and 7 not field-built yet
- Bought one at a time, the 8 plans cost $152
$99 one-time, digital download
Buy all 8 plans: $99Checkout is on Gumroad. Results depend on your water flow, fall and lift.
More sizes: not field-built yet
Each plan is a 10-page PDF with a parts list, 2 air chamber options, a build, start-up card and fix-it chart. Every size number is labeled VERIFIED (with its source) or ESTIMATE. No photos yet. When we field-build a size, you get the updated plan free.
Plans for sizes we have not built yet
- 3/4 in ram planWater in: 0.75 to 2 gpm⚠ NOT FIELD-BUILT YETBuy 3/4 in: $19
- 1 in ram planWater in: 1.5 to 6 gpm⚠ NOT FIELD-BUILT YETBuy 1 in: $19
- 1-1/4 in ram planWater in: 2 to 10 gpm⚠ NOT FIELD-BUILT YETBuy 1-1/4 in: $19
- 2 in ram planWater in: 3 to 33 gpm⚠ NOT FIELD-BUILT YETBuy 2 in: $19
- 2-1/2 in ram planWater in: 12 to 45 gpm⚠ NOT FIELD-BUILT YETBuy 2-1/2 in: $19
- 3 in ram planWater in: 20 to 75 gpm⚠ NOT FIELD-BUILT YETBuy 3 in: $19
- 4 in ram planWater in: 30 to 150 gpm⚠ NOT FIELD-BUILT YETBuy 4 in: $19
Water in: Clemson University Extension, LGP 1017. Checkout is on Gumroad. Results depend on your water flow, fall and lift.
Our Help Promise
- Stuck? Email us (see Help below). We help you troubleshoot your build.
- Wrong size? Within 30 days of purchase, we swap your plan for the right size, free.
- Free updates. If we correct a plan, or field-build its size, you get the new PDF free.
- Sales are final. Digital downloads cannot be returned, so all sales are final where the law allows. One exception: if a proven error in our plan stops your pump and we cannot fix it, we refund you.
Every plan starts with a safety page. You build at your own risk.
Parts kits and full pumps
Planned, starting with our field-built 1-1/2 in pump: a parts kit, made to order, and a full assembled pump for buyers who want it ready to set up. Pick the one you want in the sign-up below to hear first.
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Help and questions
Email help@gravityandsun.com. Tell us your fall, your lift, your flow and what the pump does. We answer as soon as we can.
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Sources and proof
Open
- VERIFIED Clemson University, LGP 1017: Homemade Hydraulic Ram Pump for Livestock Water
- VERIFIED Practical Action: Hydraulic Ram Pumps
- VERIFIED Alberta Agriculture: water-powered pumps
- VERIFIED US EPA: basic information about lead in drinking water
- VERIFIED USDA NRCS: livestock water use (MWPS-14 table)
- VERIFIED University of Minnesota Extension: watering the vegetable garden
- REPORTED Build It Solar: standpipe placement and height
- VERIFIED NWCG: 33.9 ft suction lift limit
- REPORTED USDA NRCS Range Technical Note 26: Hydraulic Ram Pumps (copy). Used for the 245 ft lift example.
- OUR FIELD RESULT Our own 1-1/2 in ram pump on our creek, run for 3 years: the build, the spring check waste valve, and the 3D model.
- OUR MATH Our own planning math: supply line friction, the 3 days of storage rule, and the 0.4 home-built pump factor.
What the tags mean: VERIFIED an official source, or 2 or more sources agree. REPORTED 1 secondary source. OUR FIELD RESULT our own pump on our own land. OUR MATH our own calculation.