A drawing of a Wirtz Pump from 1842

Passive Water Pump from Jeremy Smith on Vimeo.

Wirtz pumps have been around for a few hundred years, but haven’t been used much since steam powered pumps came along. Click here for a great resource about Wirtz pumps and the science behind them, as well as further details about the pump that was built at the Windfarm Museum in New Hampshire. Their pump uses “6 foot diameter wheel with 160 feet of 1-1/4 inch inside diameter flexible polyethylene pipe is able to pump 3,900 gallons of water per day to a 40 foot head with a peripheral speed of 3 feet per second.”

They also ran experiments that confirm that these pumps work quite well regardless of how quickly the water source (stream/irrigation ditch) is moving. The amount of water pumped increases pretty linearly with the water speed, but even at very slow speed the pump still operates at about the same overall efficiency.

An 1842 diagram showing how air and water move through a Wirtz pump

Materials used in the Pangea Farm version (total cost = ~$250)

For the paddle wheel:
– Heavy cable spool (from local utility company junk pile) for the wheel;
– Cedar 1″ thick boards for paddles;
– Paddle wheel axle, either very heavy gauge tube, or 2″ solid stock, machined at end to accept inlet of the main coil;
– Pillow block bearings to hold the axle (worth the extra cost for their durability and ability to absorb lateral force if axle is out of square with mounts).

For the scoop and coil:
– 4″ pvc scoop with wire mesh screen and reducer fittings, to scoop water into the main coil;
– Check valve between scoop and main coil, so water doesn’t flow backwards;
– Compressed air port at scoop end of coil (for blowing water out coil for winter storage);
– 100′ of 1″ poly hose, coiled on paddle wheel
– Waterproof swivel joint, joining rotating axle to the stationary pipe carrying water to holding tank.

For the storage tank and outlets:
– Reclaimed telephone poles to hold the tank up high;
– Water tank (500 gal, fills in ~8 hours);
– 1″ water line and filter from tank to irrigation system;
– Overflow line to return water to ditch when tank is full.

Lots of possibility for modification for other uses!