Build a GAP-Approved Barrel Sink

Assure your freshly harvested vegetables are pathogen-free by building this food-grade sink as part of a complete wash station.

by Dave Boyt

Clean veggies fresh from the farmers’ market are the picture of healthy eating, but they can also be the source of Salmonella, E. Coli, Listeria, and other disease-causing pathogens. Even with all the effort made by organic growers to keep their produce clean and pure, it’s still necessary to take the proper precautions.

According to Food Safety News, it has been estimated that produce accounted for 13 percent of food-borne outbreaks between 1990 and 2005. Even the most careful organic producer cannot be sure that veggies straight from the field are safe. Pathogens have been traced to irrigation water, and one fatal E. coli outbreak was traced, through DNA analysis, to wild deer. With all the care you take to provide your customers with safe, healthy produce, your last line of defense is to wash it before sending it to market.

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

What is GAP?

Good Agricultural Practices (GAP) certification was established in 1999 and funded by the USDA and the FDA as a set of voluntary guidelines designed to help producers provide pathogen-free produce. According to the Maryland Department of Agriculture, many wholesale produce buyers now require farmers to be GAP certified. Implementation of a GAP program assists farmers in providing safe, wholesome produce to consumers and meeting buyer requirements.

One step in a GAP program is to have an adequate food-safety plan, which could include how you handle produce post-harvest. The instructions below include the design and construction of simple, inexpensive washbasins that meet GAP standards.

The Leopold Model

The Leopold washing system is based on a design funded by a grant from the Northeast Center for Risk Management Education and the USDA National Institute of Food and Agriculture. The original wash-station design was developed by the Leopold Center for Sustainable Agriculture at Iowa State University and was then modified somewhat to use more readily available materials, and to better fit the scale of the small operations.

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This is more than a simple washbasin. It is a washing system that starts out with a hand-wash sink and progresses through two washbasins built from a 55-gallon, food-grade-plastic barrel split lengthwise. These plans are for building a sink that could be used as part of this system.

Build Your Sink

Step 1

When selecting a barrel for a sink basin, look for couple of characteristics. First, make sure it was used for some type of food product and not harmful chemicals. Second, get a barrel with a permanently attached lid.

Carefully cut the barrel in half lengthwise, giving you two basins. The best tool for this is a reciprocating saw, but even a hand saw could be used.

Step 2

While you can buy barrel drain-spigot kits from various garden shops or online, spigots available from hardware stores work just as well and save you a little money. Brass spigots are more expensive than plastic but are also more durable. They are available in 1/2-inch and 3/4-inch sizes. The 3/4-inch is preferable, as it will allow the sink to drain more quickly.

Drill a 3/4-inch hole in the bottom of the half-barrel, near the end. This allows you to tip the basin up to drain out the last of the wash water. Put a bead of silicon sealant around the hole on both the inside and the outside, then put the nut on the spigot and tighten it down. Give the silicon 24 hours to cure.

Step 3

Use 2×4 lumber to build the sink. Durable wood, such as redwood or cedar, are good choices. If your produce is Certified Organic, there are some restrictions about using treated lumber to support the washstand. For fasteners, I prefer to use carriage bolts and lag bolts for their superior strength—a full tub of water will weigh over 200 pounds!

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

Start out framing the barrel. The exact dimensions will depend on your barrel, but notice that the top support board is below the top of the barrel. This is to reduce the chance of contamination. I recommend carriage bolts where 4x4s are fastened face to face, and lag bolts where 2x4s are fastened face to edge. The carriage bolts should not protrude. You should countersink 1/2 inch of the nut so it doesn’t stick out.

Step 4

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

Next put in the bottom and middle supports. The middle cross supports should be about 9 inches below the top supports, so that the barrel is a couple of inches above the wood. Notice that the long bottom supports are about 3½ inches off the ground. That’s to give your toes a place to go while standing next to the sink.

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

The 1×4 diagonal braces will keep the stand from racking sideways. Use deck screws here—three on each end.

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

The 2×4 middle supports make the stand rigid and provide a frame for the shelf, if you decide to put one in. Use two carriage bolts at each end.

Step 5

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

If you wish to put a shelf under the sink, use deck screws to attach 1x4s crosswise between the middle supports.

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

Cut the plywood to fit on the shelf support and attach it to the support with deck screws.

Step 6

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

Make a final check to see that the sink fits properly.

Build a GAP-Approved Barrel Sink - Image by Dave Boyt (

You may wish to make a plywood cover for your sink to help keep it clean when you’re not using it.

This sink may be used as a stand-alone station or as part of a washing system, such as the Leopold Center’s system. It leaves you with an extra half barrel that you could use for second washing basin, or as a feeding trough, planter or dog house—that is, if you happen to have a dog that isn’t too tall.

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