Confessions of a Steward with Joel Salatin
— PART TWO —
Last month I introduced two unorthodox concepts regarding water. The first is the difference between surface runoff and the inventory of the commons (like streams, springs, and aquifers). The second is the notion that we as caretakers can greatly enhance the commons by storing surface runoff rather than pumping from the commons.
We established that one-third of all rainfall globally becomes surface runoff, which means that even a one-acre watershed in a 30-inch rainfall area will generate 10 acre-inches of surface runoff per year, or 300,000 gallons. Another surface we generally don’t think about is our impervious shelter surfaces called roofs.
A 30-inch rainfall zone generates about 20 gallons of water per square foot of roof. So a simple 2,000 square foot outbuilding or home in such a climate would collect 40,000 gallons of water a year. How many square feet of roof does your farm have? In many cases, if we include equipment sheds, barns, and the house, it’s 10,000 square feet or more. In these instances, we could collect 200,000 gallons of water per year. That means we could use nearly 550 gallons a day, assuming we could store enough.
Long ago in our area, farms depended on cisterns more than wells because in a limestone geology, digging wells is difficult. In sand substrate like much of the Midwest, wells are easy. Not in rock strata. Most farms depended on streams or springs for their water and supplemented with a cistern at the barn. In those days, digging a large cistern was cheaper than trying to dig a well through solid rock.
Both cisterns and ponds add water to the resource inventory, which is part of good stewardship. Depleting the resource inventory (commons) is not the direction a steward should go. With that established, the next major goal for cisterns and ponds is location, which should be as high in elevation as possible.
“Both cisterns and ponds add water to the resource inventory, which is part of good stewardship. Depleting the resource inventory (commons) is not the direction a steward should go.”
From this water inventory, a piping distribution system delivers the water throughout the property. What propels water through a pipe is pressure. Conventional thinking immediately assumes a pressure tank and pump system. All latent pressure, except gravity, requires energy. Like a coiled spring, maintaining that real-time pressure adds a lot of cost, switches, sensors, and high tech infrastructure. Gravity costs nothing.
The farm water problem can be summed up simply: dribbles don’t work in real-time. When you want to fill a bucket of water, you can’t stand there and wait on dribbles. When the cow herd comes to drink, dribbles won’t satisfy. But dribbles do add up over time. Even an extremely small constant flow accumulates. A one gallon per minute (gpm) flow is virtually a dribble but adds up to 60 gallons an hour and 1,440 gallons a day. That’s substantial on a flow no bigger than a pencil.
The problem is real-time delivery. Again, you can’t wait on a one gallon per minute flow to fill your water bucket or satisfy the cows, even though that dribble over a day is more than enough to satisfy major water uses. In general, the cheapest way to dispense large flows in real-time is to dribble into high terrain storage that uses gravity to pressurize the system and generate high momentary flow.
One of the most elegant domestic water systems I ever saw was a friend who had a rain catchment system from his house roof that flowed into an underground cistern. He hooked up a bicycle to a water pump and in 5 minutes a day could “ride” enough water to an attic cistern to meet each day’s water requirements. The 200-gallon tank in the attic gravity flowed to the hot water tank, shower, and toilet without any pumps or pressure tanks. The only energy required in the system was a 5-minute daily bike ride.
Gravity pressurizes water at .432 pounds per vertical foot. While 10 feet at 4.3 pounds of pressure doesn’t sound like much, it’s enough. If you had a nearby tree you could pull an IBC tote up 40 feet, and get nearly 20 pounds of pressure by gravity. This is why cities use water towers. They can dribble (relatively) water 24 hours a day and use gravity to supply momentary flow when everyone comes home from work and takes a shower…
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Joel Salatin co-owns, with his family, Polyface Farm in Swoope, Virginia. Four generations of his family currently live and work on the farm, and his farm services more than 5,000 families, 50 restaurants, 10 retail outlets, and a farmers’ market with salad bar beef, pigaerator pork, pastured poultry, and forestry products. When he’s not on the road speaking, he’s at home on the farm, keeping the callouses on his hands and dirt under his fingernails, mentoring young people, inspiring visitors, and promoting local, regenerative food and farming systems. Salatin has published 15 books, and he is the editor of The Stockman Grass Farmer, granddaddy catalyst for the grass farming movement. He passionately defends small farms, local food systems, and the right to opt out of the conventional food paradigm.