Choose a cache container by its seal and its resistance to gnawing, in that order: a 5-gallon plastic bucket with a gasketed gamma-seal lid, a length of 10-15 cm PVC pipe with glued end caps, or an ammunition can with an intact rubber gasket. Plastic keeps water out but rats can chew it, so put plastic inside a metal or wire shell if rodents are present, and avoid rusting metal cans, cardboard and glass.
Part of Hidden Food Caches
Cache container selection is the matching of a sealed vessel to what it must keep out: water, air, rodents and crushing soil.
The Seal Fails Before The Wall Does
The parent article ranks containers for burial. Best: 5-gallon plastic buckets with screw-top gamma seal lids, which it calls watertight, rodent-proof and widely available before collapse. Good: PVC pipe 10-15 cm in diameter with glued end caps, cut to length, loaded, and the second cap glued on; and ammunition cans with intact rubber gaskets, waterproof, crush-proof and compact. Acceptable: doubled, tied plastic bags, cheap but vulnerable to puncture and rodents. Poor: metal cans (they rust), cardboard (absorbs moisture) and glass (fragile).
One word in that ranking needs correcting. Plastic is not rodent-proof. Feed Storage and Rodent Prevention says rats chew through wood, plastic and burlap, and Physical Pest Barriers gives the openings that stop them: a maximum of 12 mm for rats and 6 mm for mice. A bucket is watertight against groundwater; against a determined rat it is a chewable shell. The container choice therefore depends on whether rodents are likely to dig down to it.
The other article on this subject, Emergency Caches, puts steel ammunition cans first, with clay pots sealed by wax and resin and sealed wooden boxes lined with tin as alternatives. The two lists agree that the lid seal matters most and disagree on the order; both fit a rule of thumb: for wet soil choose the best gasket, for rodent country choose metal or a mesh jacket.
What You Need
- A food-grade container that never held chemicals, paint, fuel or soap
- A gasket or glued seal you can test
- Liners — plastic bags, as the parent article advises, even inside a waterproof container
- Wire mesh with an opening no larger than 6 mm, if rodents are likely
- Wax for the seam
Method: Test The Seal, Then Armour It
Step 1: Pick a container with a seal you can test. Press-fit, screw-on and gasketed lids can be tested; a lid you cannot check is a hope.
Step 2: Test it with water. Fill with water or put in an empty tied bag, close the lid, turn it upside down, and look for leaks after some hours. Pipe with glued caps needs the glue to cure fully first.
Step 3: Check the container’s history. A bucket that held anything other than food can taint the contents; the smell of the previous contents is a sign.
Step 4: Match the shell to the pest. In rodent country, wrap the container in mesh with openings of 6 mm or less, or put a plastic bucket inside a metal can or a drum. See Pest Prevention.
Step 5: Protect against crushing. Soil load and later digging can crush thin plastic; thicker walls and rounded shapes resist better. A pipe stands up to soil better than a flat-sided box.
Step 6: Weigh the full container. You must be able to lift it out. A full bucket is heavy; see below.
Worked Example: How Much Does One Bucket Hold?
A 5-gallon US bucket is about 18.9 L (5 × 3.785 L). A pipe 15 cm across and 1 m long, taking 15 cm as the inside diameter for simplicity, holds π × (0.075 m)² × 1.0 m = 3.1416 × 0.005625 × 1.0 = 0.01767 m³ = 17.7 L, about the same as a bucket. Real PVC walls are thick, so the inside diameter is smaller and the true volume is less.
- At an assumed rice density of 0.8 kg per litre (recalled; weigh your own), 18.9 L is about 15 kg.
- For a household of 4 at 0.55 kg of rice per person per day (from Inventory Management), 4 × 0.55 = 2.2 kg a day, so one bucket supplies 15 ÷ 2.2 = 6.8 days.
A two-week backup cache for four, as in the parent article, therefore needs 14 × 2.2 = 30.8 kg, or about two buckets of rice.
Common Mistakes
- Trusting “rodent-proof” on a plastic bucket. Check for gnawing every visit.
- A reused paint or chemical bucket. It taints food and can poison.
- A rusted can of unknown age as a buried container. It is perforated within a season.
- Packing the container too heavy to lift. A single person has to be able to dig it up and carry it.
Safety
Plastic, solvents and heavy lifts
PVC cement and primer are flammable and their fumes harmful; use outdoors, away from flame. Do not store food in containers that held fuel, pesticides, chemicals or soap, and never use a container whose former contents you do not know. Buried cans of old food may be swollen: do not open or taste them, see Waterproofing and Preservation. A full bucket of grain is a lifting injury; bend at the knees and share the load.
What’s Next
- Learn next: Moisture Control — keeping what is inside the container dry
- Combine with: Pest Prevention — what to do about the animals that test the container